Ruff Idle ,Huge Loss of Power

[Tripler]

Hey guys/gals . Was driving the 1995 Z today and all of a sudden the engine lost power and developed a ruff idle . It also seemed to be running on very few cylinders . It was working fine on the highway but once I got close to home , it began the loss of power and ruff idle in city traffic . Would a gas cap not being tight enough create this issue ? Also could it be the fuel filter ? It has a half filled gas tank and car always gets Shell 91 octane Ethanol free gas .



Thanks

Mike

[secondchance]

Hey guys/gals . Was driving the 1995 Z today and all of a sudden the engine lost power and developed a ruff idle . It also seemed to be running on very few cylinders . It was working fine on the highway but once I got close to home , it began the loss of power and ruff idle in city traffic . Would a gas cap not being tight enough create this issue ? Also could it be the fuel filter ? It has a half filled gas tank and car always gets Shell 91 octane Ethanol free gas .



Thanks

Mike

Hi Mike!

Did it backfire? First, I would check MAP sensor hose between the MAP sensor and the back of the plenum.
Loose gas cap wouldn’t cause symptoms you are seeing.

[dredgeguy]

Hi Mike, sounds like a problem I had in the past. One of the fuel pump hoses was loose and just hanging. The fix was new hose clamps. Good luck and keep us posted.

[Tripler]

Hey . Thanks for quick responses . I will give those tips a look tomorrow . Thanks 😊
Mike

[Tripler]

Hi Mike!

Did it backfire? First, I would check MAP sensor hose between the MAP sensor and the back of the plenum.
Loose gas cap wouldn’t cause symptoms you are seeing.
Actually it did backfire once .

Thanks for the tip .

[Tripler]

Hi Mike, sounds like a problem I had in the past. One of the fuel pump hoses was loose and just hanging. The fix was new hose clamps. Good luck and keep us posted.
Hey Charlie ! Hows things . Finally got warm weather up here so busy tuning my motor bikes ( I have 3 , 2 plated and one for track only ) and of course getting the Z and the 6 out once a week at least . I will be looking at the car this morning and will let you know what I find .



Mike

[Tripler]

Morning. A small hard black hose was not attached to a softer rubber 90 elbow. Is that the MAP Sensor ? . I reconnected it but still runs a bit ruff . Do I need to take it for a drive to reset everything ? Should I be looking for anything else ?
Mike

[secondchance]

Morning. A small hard black hose was not attached to a softer rubber 90 elbow. Is that the MAP Sensor ? . I reconnected it but still runs a bit ruff . Do I need to take it for a drive to reset everything ? Should I be looking for anything else ?
Mike

A small hard black hose was not attached to a softer rubber 90 elbow. Is that the MAP Sensor ?

Was this hose between the back of the plenum to underside of MAP sensor? MAP sensor is under an aluminum trim behind the plenum. Once reconnected, all should return to normal. If not, I suspect something else blew off under the plenum on top of MAP sensor hose when it backfired.

[dredgeguy]

Hi Mike, all well here. Sitting in Dhaka, Bangladesh now until the end of the month. Hope you track down the problem. When my issue started, engine felt like it was going to stall and that is when we found one of the fuel pumps disconnected. Keep us posted.

[Mystic ZR-1]

Dhaka Bangladesh!
Damn!!!
Charlie, I know I’ve said it before, but,
you get to go to the places us mere mortals can
only dream about!!!

[dredgeguy]

Sure thing but sometimes dreams can turn into nightmares. Have a few stories to tell you at Carlisle. Flying down the middle of the Straits of Hormuz and cutting east over Iran in a 777 when missiles are in the air will keep the pucker factor very high!

[Tripler]

Sure thing but sometimes dreams can turn into nightmares. Have a few stories to tell you at Carlisle. Flying down the middle of the Straits of Hormuz and cutting east over Iran in a 777 when missiles are in the air will keep the pucker factor very high!


YIKES ! I would use another word than pucker but then I would get banned from the site lol !



Stay safe ...
Mike

[Tripler]

A small hard black hose was not attached to a softer rubber 90 elbow. Is that the MAP Sensor ?

Was this hose between the back of the plenum to underside of MAP sensor? MAP sensor is under an aluminum trim behind the plenum. Once reconnected, all should return to normal. If not, I suspect something else blew off under the plenum on top of MAP sensor hose when it backfired.
Yes it was . I am going to put a plastic ty on it to squeeze it tighter . Could not drive it today . Movie shoot on our street took up all our car moving spots and a bit of rain .

Started it and it sounded better but not a smooth as it used to be .

Thanks for the tips

Mike

[Tripler]

Drove it around the block . Feels like a 6 or 4 and is still running ruff . Bought a video scope to look under the plenum .
Also on another note , the car only backfired 3 or 4 times since we have owned it since 2016 and it would only do it going down a hill with my foot off the gas pedal in second gear, just a small pop but it did not always happen . Just once in a blue moon .
Mike

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[secondchance]

Drove it around the block . Feels like a 6 or 4 and is still running ruff . Bought a video scope to look under the plenum .
Also on another note , the car only backfired 3 or 4 times since we have owned it since 2016 and it would only do it going down a hill with my foot off the gas pedal in second gear, just a small pop but it did not always happen . Just once in a blue moon .
Mike

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If you hear a pop going down hill with foot off, my guess is unburned fuel mixture going downstream and lighting up. This should not cause MAP blow-off. MAP sensor hose blows off when you back fire during the engine start.

Again, it's just a WAG - if MAP hose is intact and still suffering from misfire, either a fuel system issue (like fuel pump, clogged fuel filter, etc.) or a vacuum blown under the plenum.
I presume CEL is not on? Can you see if you can jump OBD and pull code?

[Paul Workman]

If that MAP hose(s) were disconnected and now restored, I'd wanna pull and inspect the plugs. Could be some plug(s) got fouled and will run OK when they are cleaned up.

Experience is generally a good thing when troubleshooting; it can lead one to the issue sometimes immediately. But! If guessing at the solution proves not to be the case (fix), it"s back to the basics time!

FUEL PRESSURE (static) = ?
Current draw on the pump diagnostic test point (red wire about 5cm long w/ a black terminal sticking out of the large wire loom near the W/S wiper motor) when ignition key is in the OFF position [8-10 amperes is normal for both pumps running nornally].

Let us know what U find...

[Paul Workman]

Next:

When you shut off the ignition switch, does fuel pressure hold to within a pound or two for 10-15+ minutes, or drop to zero briskly?

[Tripler]

If you hear a pop going down hill with foot off, my guess is unburned fuel mixture going downstream and lighting up. This should not cause MAP blow-off. MAP sensor hose blows off when you back fire during the engine start.

Again, it's just a WAG - if MAP hose is intact and still suffering from misfire, either a fuel system issue (like fuel pump, clogged fuel filter, etc.) or a vacuum blown under the plenum.
I presume CEL is not on? Can you see if you can jump OBD and pull code?
Yes . My first thought also . ordered a new fuel filter . Will be changing that first and go from there .

I am not sure how to jump OBD to see if there is a code . Sorry .


Thanks for the tip .

Mike

[Tripler]

If that MAP hose(s) were disconnected and now restored, I'd wanna pull and inspect the plugs. Could be some plug(s) got fouled and will run OK when they are cleaned up.

Experience is generally a good thing when troubleshooting; it can lead one to the issue sometimes immediately. But! If guessing at the solution proves not to be the case (fix), it"s back to the basics time!

FUEL PRESSURE (static) = ?
Current draw on the pump diagnostic test point (red wire about 5cm long w/ a black terminal sticking out of the large wire loom near the W/S wiper motor) when ignition key is in the OFF position [8-10 amperes is normal for both pumps running nornally].

Let us know what U find...
Yes . Will be pulling the plugs and let you know whats up . The way it was running I guarantee there fouled for sure . Will clean them first before fuel filter change and see if it runs smoother .

Thanks Paul .

Mike

[Tripler]

Next:

When you shut off the ignition switch, does fuel pressure hold to within a pound or two for 10-15+ minutes, or drop to zero briskly?


How would I check fuel pressure ? Do I need to attach a gauge somewhere along the fuel line ?



Thanks



Mike

[Tripler]

I am seeing and smelling gas inside this 90 elbow . Obviously the car is flooding . Tried looking under the plenum with the scope but that's useless as I have no idea what I would be looking for https://uploads.tapatalk-cdn.com/20190627/25a545c8028b80e225d66da2d0ed62c6.jpg

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[Tripler]

Is there supposed to be something attached to this brass spigot ? I don't ever remember seeing anything attached before . The tube you see is the scope as I used it's lights to highlight the spigot
https://uploads.tapatalk-cdn.com/20190627/eaeb28aa5fa86f1fae64760cde50dc23.jpg

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[Ccmano]

Is that elbow in the vacuum line to the fuel pressure regulator? If there’s gas there the fuel pressure regulator has failed, could be the source of you problem.

The “spigot” you refer to (if I interpreted you post correctly) is the vent for the vacuum solenoid. No lines attach there.
H

[Ccmano]

If you have a hand held vacuum pump attach it to the fuel regulator and pump it up to no more than 10 psi. If the vacuum doesn’t hold the regulator is bad.
H
:cheers:

[Paul Workman]

How would I check fuel pressure ? Do I need to attach a gauge somewhere along the fuel line ?



Thanks



Mike

There is a Schrader valve at the front of the passenger side fuel rail. Attach a pressure gauge there for static pressure tests, (AND (FYI) if you purchase an extension hose, you can do impromptu dynamic tests by taping the pressure gauge to the windshield and going for a drive (not necessarily applicable to this particular problem))

[Paul Workman]

:happy1:Is that elbow in the vacuum line to the fuel pressure regulator? If there’s gas there the fuel pressure regulator has failed, could be the source of you problem.

The “spigot” you refer to (if I interpreted you post correctly) is the vent for the vacuum solenoid. No lines attach there.
H

[Tripler]

There is a Schrader valve at the front of the passenger side fuel rail. Attach a pressure gauge there for static pressure tests, (AND (FYI) if you purchase an extension hose, you can do impromptu dynamic tests by taping the pressure gauge to the windshield and going for a drive (not necessarily applicable to this particular problem))So 200 mph tape then [emoji39]

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[Ccmano]

If the fuel pressure regulator is bad, with raw fuel being pulled into the plenum from a ruptured membrane, checking the fuel pressure is largely irrelevant. Assuming the fuel pumps are good you will simply see maximum pressure ~50psi.
H
:cheers:

[Mystic ZR-1]

Two observations:
That‘s 10 inches of Hg, vacuum, not 10 psi pressure...
100 mph tape should do the job, 200 mph rating not required...
😋

[Tripler]

So from what I am reading and from what you guys are saying , the fuel pressure regulator is toast . Any idea where I purchase a new one and also how difficult are they to change out .



Is this the right one ?
https://www.ebay.com/itm/Fuel-Injection-Pressure-Regulator-Delphi-FP10016/323739727277?epid=75990786&hash=item4b606435ad:g:h8oAAOSwxMRbnQfo


Also reading Dynomites blog .
https://www.corvetteforum.com/forums/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-15.html#post1596384563



Thanks



Mike

[Tripler]

On another note , is there a trick to getting plugs out of an LT5 ? I tried 2 that were easily accessible and had no luck . Maybe my old arthritic hands have lost there old man strength lol .

Mike

[32valvZ]

On another note , is there a trick to getting plugs out of an LT5 ? I tried 2 that were easily accessible and had no luck . Maybe my old arthritic hands have lost there old man strength lol .

Mike

try a 1/2" set up with a breaker bar.

[Tripler]

try a 1/2" set up with a breaker bar.
Agree but is there an off chance that the larger wrench would break the plug off ? That was my concern . Not used to working on this beast as I only work on small car engines and motorcycles mostly and did not expect these plugs to be as tight as they are . Yikes .

Thanks for the tip.


Mike

[secondchance]

Agree but is there an off chance that the larger wrench would break the plug off ? That was my concern . Not used to working on this beast as I only work on small car engines and motorcycles mostly and did not expect these plugs to be as tight as they are . Yikes .

Thanks for the tip.


Mike

As long as your socket is securely over the hex portion of the plug it won't break the plug. When the spark plug breaks, it's between the metal hex and ceramic body. However, if the plug is seized on to the head, I imagine, one could strip the thread off the head.
I myself, if concerned, might vacuum the plug hole as much as possible and blow out with compressed air, spray WD40, let it soak overnight and loosen. However, WD40 in the hole can lead to dirt flowing into the combustion chamber when the plug is removed.

[secondchance]

So from what I am reading and from what you guys are saying , the fuel pressure regulator is toast . Any idea where I purchase a new one and also how difficult are they to change out .



Is this the right one ?
https://www.ebay.com/itm/Fuel-Injection-Pressure-Regulator-Delphi-FP10016/323739727277?epid=75990786&hash=item4b606435ad:g:h8oAAOSwxMRbnQfo


Also reading Dynomites blog .
https://www.corvetteforum.com/forums/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-15.html#post1596384563



Thanks



Mike

First one off Ebay will not work.
Second one is Phil's modified serviceable fuel pressure regulator.

Maybe someone with a good used one will chime in.

[Tripler]

Just looking over Phil's amazing build !

http://www.zr1.net/forum/showthread.php?t=28304

[Tripler]

Thanks for the replies secondchance .

Mike

[Ccmano]

Just looking over Phil's amazing build !

http://www.zr1.net/forum/showthread.php?t=28304

Agreed the eBay one will not work. Unless you find a correct one on eBay or someone is gracious enough to sell one out of their stash, contact Phil and see if he will repair yours.

I use this setup for the #8 plug, a straight extra long extension works for the rest. Notice that the spark plug socket has the universal built in. When unseating a plug I use a quick snap of force against the ratchet handle to get them unseated.

https://farm66.staticflickr.com/65535/50111684903_4debb2aaac_c.jpg (https://flic.kr/p/2jmcu4i)

Paul rightly points out that if you do a fuel pressure test, not looking so much actual pressure, but if the fuel pressure bleeds off quickly when the pumps shut down, that’s another indicator that the pressure regulator is bad.
H
:cheers:

[Tripler]

Agreed the eBay one will not work. Unless you find a correct one on eBay or someone is gracious enough to sell one out of their stash, contact Phil and see if he will repair yours.



I use this setup for the #8 plug, a straight extra long extension works for the rest. Notice that the spark plug socket has the universal built in. When unseating a plug I use a quick snap of force against the ratchet handle to get them unseated.



http://a65.tinypic.com/311t654.jpg



Paul rightly points out that if you do a fuel pressure test, not looking so much actual pressure, but if the fuel pressure bleeds off quickly when the pumps shut down, that’s another indicator that the pressure regulator is bad.

H

:cheers:Good info . Thanks . I was able to get the right side plugs out just using a 1/4 inch drive and mustering up old man strength. They were not as tight as I originally thought so got them all out . They all smelled raw gas , seemed wet and also do not look fouled . The four were a light tan brown .
Pics of plugs from front of engine to firewall.
https://uploads.tapatalk-cdn.com/20190628/2cb750b068cc889b11d2a848d3239089.jpghttps://uploads.tapatalk-cdn.com/20190628/bfb4c85854eb3e34c8c83ff53e42ae81.jpghttps://uploads.tapatalk-cdn.com/20190628/d9b9271b3ab83755fd5e076930f67fa0.jpghttps://uploads.tapatalk-cdn.com/20190628/85c94501865f89e2d4b3805dcffef2a9.jpg

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[Tripler]

Also picked this wobble extension set up for $11 canuck. Usually $70 .https://uploads.tapatalk-cdn.com/20190628/1a5ac26f8053799440f02751d49bb263.jpg

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[Tripler]

https://www.youtube.com/watch?v=EDt5IYIB5k8

[Tripler]

Bit off topic but thought you might enjoy this .
Kid puts me to shame with his mechanical skills and he can get to the tight spots easy lol . One lucky boy to be working on a ZR-1 so young .

https://www.youtube.com/watch?v=pXWg84w98l4

[Ccmano]

Bit off topic but thought you might enjoy this .
Kid puts me to shame with his mechanical skills and he can get to the tight spots easy lol . One lucky boy to be working on a ZR-1 so young .

https://www.youtube.com/watch?v=pXWg84w98l4

Cool Kid! That’s how you get them started early. I wonder if his dad or grand dad are members here?
H
:cheers:

[cp1joel]

Hi Mike,

How did you go sorting your Ruff Idle, loss of power issue?

Have experienced this multiple times.

Cheers

[Tripler]

Hi Mike,

How did you go sorting your Ruff Idle, loss of power issue?

Have experienced this multiple times.

Cheers
Hey . How's things .

Just got off the phone with Marc Haibeck and ordered the DVD plenum pull video and the throttle body bypass tube . Since I am draining the car by 2 litres as per Marc's instructions , I may as well install the bypass .

Also when talking to Marc and I told him what the car was doing he told me I did not have to tell him anymore info as it is definitely the FPR .

Been in contact with Phil also and once I get the FPR out I will mail it to Phil to be modded .

Looks like this will be a month or 2 process but the beast will run again .
Also have to call Jerry's Gaskets and order new o rings for the injectors .

FPR .

Mike

[Tripler]

Hi Mike,

How did you go sorting your Ruff Idle, loss of power issue?

Have experienced this multiple times.

Cheers
So you have also had this issue ? Have you replaced the FPR ? Did you giVe Marc Haibeck a call or hit up the issue on this forum ? Just curious how you got it sorted and what where the issues if not the FPR .

Thanks



Mike

[Tripler]

If the fuel pressure regulator is bad, with raw fuel being pulled into the plenum from a ruptured membrane, checking the fuel pressure is largely irrelevant. Assuming the fuel pumps are good you will simply see maximum pressure ~50psi.
H
:cheers:
hooked up the pressure gauge

and it stays at 48 psi . I did not start the engine ,only with key on .


Thanks



Mike .

[Tripler]

There is a Schrader valve at the front of the passenger side fuel rail. Attach a pressure gauge there for static pressure tests, (AND (FYI) if you purchase an extension hose, you can do impromptu dynamic tests by taping the pressure gauge to the windshield and going for a drive (not necessarily applicable to this particular problem))


Tight fit but I was able to attach a fuel pressure gauge . With key on , pressure held at 48 psi for 3 minutes or so .

Thanks



Mike

[Tripler]

Added some lighting to do the operation . Be going in next week .
Plenum, Injectors , FPR removal
https://uploads.tapatalk-cdn.com/20190724/159a87f04cc62629d891eec25379e9e0.jpghttps://uploads.tapatalk-cdn.com/20190724/d1d14cfb5be38d2f96e4b5c223f3e2c4.jpghttps://uploads.tapatalk-cdn.com/20190724/57dbdb19452b4d20a209ef8a30885f6c.jpg

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[Tripler]

Found an interesting way to drain the plenum , unless some of you guys already have done this . I hooked a small hose to the glycol fluid tube at the lowest point of the plenum towards the firewall on the right side . Then the fluid will automatically syphon out into a lower point , in this case , a measured dish for 2 litres marked so I knew how much I removed . Obviously radiator fill cap is removed or open. You will hear the fluid syphon out and just watch your fill dish level and pinch off the the hose or remove it and voila, no fluid in the plenum .

I tried using a mechanical way to suck out the glycol , but nothing was happening so then tried the hose trick and that worked great .

https://uploads.tapatalk-cdn.com/20190815/459f29189cae9059f125e5cead7bb96d.jpghttps://uploads.tapatalk-cdn.com/20190815/394dbcc3d80e6ab2f5fa49ba34844a44.jpg

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[tiegsd]

Thanks for the tip.

Sent from my SM-N920V using ZR-1 Net Registry mobile app (http://r.tapatalk.com/byo?rid=90383)

[Tripler]

Thanks for the tip.

Sent from my SM-N920V using ZR-1 Net Registry mobile app (http://r.tapatalk.com/byo?rid=90383)
I found there is still a little bit of glycol in the plenum when i lifted it up a bit so put a rag or paper towels to grab the spill. Mark Haibeck , in his plenum removal video states that there will still be fluid in the plenum when you lift it so be prepared .



Mike

[Tripler]

Plenum off and injectors removed . Used one of my plastic panel removal tools to work the injectors out . Worked like a charm . Injectors popped out with very little struggle .https://uploads.tapatalk-cdn.com/20190819/9502f8150caa6324597607a57c0644a1.jpghttps://uploads.tapatalk-cdn.com/20190819/34ee121d6b31175fb7b174b0e4aec571.jpg

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[cp1joel]

Hi Mike,

Good to see that you are hopefully getting to the bottom of your issues. I am looking forward to seeing if this fixes the idle and power issues.

I took the Z out for a drive yesterday and the car ran very well. What was interesting though, was when the A/C was turned on, my rough idle and loss of power seemed to return.

The car started to get sloppy again when stopped at lights and in traffic.

Once the A/C was switched off, it drove a lot better (even with the bigger cams and the run-in tune )

Anyway food for thought.

Cheers

Joel

[Tripler]

Hey Joel . That is strange indeed . Maybe the guys on the forum can help . Start a new thread perhaps . The AC was not an issue with our car . It felt like it was flooding or running on only a few cylinders . All vacuum hoses where attached when I removed the plenum other than the FPR vacuum line which kept popping off which hinted at the FPR may be the issue and failed . No fault codes appeared either .
Jagpanzer just finished up my FPR which is now a IFPR . Hope to get it back sometime next week . I still have to replace all the o-rings on the injectors and of course the fuel lines going into the IFPR . I thought it might be easier to do the o-rings with the fuel rails attached to the IFPR . I am also using 2 stroke motor oil as my lube to insert the injectors and 0-rings . Looking forward to putting it back together .

Mike

[XfireZ51]

Hi Mike,

Good to see that you are hopefully getting to the bottom of your issues. I am looking forward to seeing if this fixes the idle and power issues.

I took the Z out for a drive yesterday and the car ran very well. What was interesting though, was when the A/C was turned on, my rough idle and loss of power seemed to return.

The car started to get sloppy again when stopped at lights and in traffic.

Once the A/C was switched off, it drove a lot better (even with the bigger cams and the run-in tune )

Anyway food for thought.

Cheers

Joel

Joel,

If u have bigger cams(and I presume u ported top end), the additional load ur putting on motor when turning on A/C is causing the ECM to use a different part of the VE and SA tables. If u haven’t addressed those areas while tuning, its likely they’re inadequate for handling the A/C request. Plus, the bigger cams lower the overall vacuum at idle so u will probably need to increase IAC steps to maintain idle w the additional load. Maybe even SA.
What happens is that the motor starts to oscillate as the ECM tries to maintain idle and stall saver kicks in. The stock tune will have too much compensation for the larger cams and u get a seesaw effect.

[Tripler]

Got the rebuilt IFPR yesterday . Thanks Phil . This adds some serious bling to the motor . Looks amazing .
Replacing O-rings today on fuel rail and fuel lines to IFPR .

https://uploads.tapatalk-cdn.com/20190911/c631018d0293935b188980b1a6bb3924.jpg

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[Tripler]

Assembled IFPR to fuel rails.
Hoping to install the plenum tomorrow after functional tests are completed as per Marks instructional Plenum video shows . https://uploads.tapatalk-cdn.com/20190911/87ac5f010515cdaeed2acb1a83195cbd.jpg

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[Tripler]

IFPR and rails back in place . https://uploads.tapatalk-cdn.com/20190911/b8eca08f062df3a800157aacf9a89671.jpg

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[Tripler]

System back together . Huge thanks to Marc Haibeck for his instructional Plenum Removal and Plenum reinstallation video . I would have been beyond lost without his help . Now that it's back together, running much better with the IFPR from Phil but still down on power and a ruff idle . I am taking the car to my local garage to have a look and have them hook it up to do a diagnostics .

Mike

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[Tripler]

If that MAP hose(s) were disconnected and now restored, I'd wanna pull and inspect the plugs. Could be some plug(s) got fouled and will run OK when they are cleaned up.



Experience is generally a good thing when troubleshooting; it can lead one to the issue sometimes immediately. But! If guessing at the solution proves not to be the case (fix), it"s back to the basics time!



FUEL PRESSURE (static) = ?

Current draw on the pump diagnostic test point (red wire about 5cm long w/ a black terminal sticking out of the large wire loom near the W/S wiper motor) when ignition key is in the OFF position [8-10 amperes is normal for both pumps running nornally].



Let us know what U find...Hi Paul . So the amp draw is only 7 amps and the fuel pressure reading was at 47 psi [emoji849][emoji3525][emoji853]

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[Ccmano]

Hi Paul . So the amp draw is only 7 amps and the fuel pressure reading was at 47 psi [emoji849][emoji3525][emoji853]

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You have at least one bad pump. Pull the FP1 pump fuse and check again. That will give you the reading for FP2. Subtract that number from the combined number (in your case 7 amps) and you’ll have the reading for FP1. You might as well just replace both pumps while your in there.
H
:cheers:

[Tripler]

You have at least one bad pump. Pull the FP1 pump fuse and check again. That will give you the reading for FP2. Subtract that number from the combined number (in your case 7 amps) and you’ll have the reading for FP1. You might as well just replace both pumps while your in there.
H
:cheers:
Thanks . Yes , if one is bad , may as well change both . thanks again for all the help Ccmano and :cheers: from everyone on the forum .



Recommendations for which pump to purchase ?

1995 ZR-1









Mike

[Tripler]

So we have been looking at getting a pump for the Z but man , its confusing as hell . There seem to be a plethora of numbers and make's , so which do you guys recommend for a 1995 ZR-1 ?

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[dredgeguy]

Hi Mike, we are having a maintenance day this Saturday at Jim's....wish you were here. I have 2 extra sitting on my shelf. I use Electric Performance fuel pumps part number:
P-240KC. I think I got them at RockAuto. If you have any problems finding them, let me know and I will put my 2 in the mail to you.

[Tripler]

Hey Charlie . Last I looked , they were out of stock .

Thanks

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[Tripler]

I willl check again tomorrow . Do they also have the socks and gaskets ?
Thanks


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[dredgeguy]

Just checked and they have them for a great price, $18.13 each! Yes the kit includes the socks and gaskets
https://www.rockauto.com/info/166/P240KC__ra_p.jpg

[Tripler]

Just checked and they have them for a great price, $18.13 each! Yes the kit includes the socks and gaskets
https://www.rockauto.com/info/166/P240KC__ra_p.jpg




Awesome thanks . Guess I was looking at the wrong site . I was looking for the entire unit but this will work indeed .



Mike

[dredgeguy]

Order 2

[Tripler]

Order 2


Sure did ;)

[Tripler]

Changed out the fuel filter today . Gas that spilled out of it looked rusty . Also retested the amp draw on the fuel pumps , 8 amps now .
I also pulled the plugs and found one that was whitish . The others looked grey or slightly dark in color . The whitish plug was either number 5 or 7 .
Also engine runs very smooth at 2000 + rpm but still has a rough idle .
With the one plug looking off , is it ok to take the car out for an Italian tuneup or just a simple test drive ?
From reading the manual and searching online , white means lean . I don't want to hole a piston .
Thanks
Mike

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[Tripler]

Had some fun today . Replaced both fuel pumps . Found out after installation that one of the pumps did not work . So removed the sender and tried both of the old pumps . I can get the sender in and out in under 5 minutes now . The old pump and the new pump are both reading 3 amp draw now ?
What givez ? Why am I reading 3 amps on the new pump ? :(
RockAuto is sending me a new pump .

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[XfireZ51]

Do u see any flecks of metal in the ceramic insulator? If u r datalogging, are u picking up any knock?

[Tripler]

Do u see any flecks of metal in the ceramic insulator? If u r datalogging, are u picking up any knock?I am clueless as to what you just asked me . Sorry .

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[XfireZ51]

Pull a few spark plugs and see if there are any specks of metal embedded in the ceramic (insulator) portion of the tip. If there is, that would confirm detonation.
If not, then although those cylinders may be running lean, u likely don’t have a danger of “holing” a piston.

[Tripler]

Pull a few spark plugs and see if there are any specks of metal embedded in the ceramic (insulator) portion of the tip. If there is, that would confirm detonation.

If not, then although those cylinders may be running lean, u likely don’t have a danger of “holing” a piston.Morning . There is only the one plug, #5 that is white or light grey in colour . I will look closer for specs . Thanks .
Since changing out fuel filter, car runs slightly better but still ruff idle , low on power .


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[Tripler]

Any idea where I can get a new float/plastic foam for the fuel level arm ? The one on our car is cracked and is absorbing fuel .

[Jagdpanzer]

I have one for you if I can find it.
PM your address.


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[Jagdpanzer]

Found the one I have
11218


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[Tripler]

Found the one I have
11218


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Thankyou very much . Got it yesterday . Now just need some warmer weather to install it .



;)

[Tripler]

Found the one I have
11218


Sent from my iPhone using ZR-1 Net Registry (http://r.tapatalk.com/byo?rid=90383)Installed the float a few weeks ago . Checked it yesterday and it works perfectly . Fuel is now showing full, not 3/4 like it used too when the tank was actually full .
Thanks

Mike

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[Tripler]

Got the car up and running with new Summit Racing Injectors . Running smoother but still ruff idle . Smooths out exactly at 2000 rpm . Should it not now idle correctly with new injectors ? I have done the battery disconnect twice now to reset ECM .
What is the next step I should be looking at ?
Be doing a test drive today .
Will post later how it went .



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[XfireZ51]

Which injectors are u using? Is there a number?

[Tripler]

ACC- 150821
Car is the same . Test drive went badly .

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[Tripler]

Accelhttps://uploads.tapatalk-cdn.com/20200714/2991b075bdd0e65dd3e7069a2ecdf5a8.jpg

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[Ccmano]

What year is your car? 93 or later? I noticed the EGR hose on an earlier photo you posted. If so have you checked the EGR valve and it?s control circuit? An EGR valve that is hanging open will cause these types of issues. Refer to your FSM for testing.
H
:cheers:

[XfireZ51]

Yes ok. Accels. That?s what I thought. Any chance u checked coils and wires before putting plenum back on.

P.S. Just a hint. Always order multiple sets of plenum gasket sets from Jerry. 🤣🤣

[Tripler]

1995 . No , I did not check the coils . How would I check the coils .
Thanks
Yes , ordering 2 new gasket sets .
Also another has popped up . No AC now . Yikes

Mike

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[Ccmano]

1995 . No , I did not check the coils . How would I check the coils .
Thanks
Yes , ordering 2 new gasket sets .
Also another has popped up . No AC now . Yikes

Mike

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Check the EGR first...
H
:cheers:

[Tripler]

What is the EGR and how do I test it.

Mike

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[Tripler]

Tried to find info on the EGR in the manual . We could not find info on a EGR .
In the mean time , I changed the oil and will be looking to see why the AC did not come when it worked last time I pulled the plenum to change the FPR .

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[Ccmano]

What is the EGR and how do I test it.

Mike

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EGR... Exhaust Gas Recirculation. An emissions device used on vehicles from the 90s through (to a small degree) today. It puts exhaust gasses back into the intake to help minimize NoX emissions. The valve should be closed at idle and gradually opens as rpms and load come up. If it stays open at idle and low rpm rough running is the result. You will need an FSM (Factory Service Manual) to test it properly. If your doing any type of work on these cars an FSM is a must have. Internet input, as you have seen from this thread, will send you in a million different directions. Follow the test procedures in the FSM. As a stop gap measure find the EGR valve and the tube that goes to your intake manifold. It goes in right behind the IAC valve on the passenger side of the plenum. Disconnect the tube from the plenum. Find a way to plug the tube (an accordingly sized rubber stopper will do the trick) Then reconnect the tube to the plenum. Please make sure that whatever you plug it with can?t be sucked into the plenum! If that solves your problem your EGR is the issue. Usually they stick open when they go bad. But please... get an FSM and read up on the various LT5 systems. There is also a commonly available training manual that does an excellent job of explaining the various systems. I believe LGAFF sells them on CD.
H
:cheers:

[Tripler]

Wow . Thanks
Yes I have the FSM , 2 huge red books . Thanks for that very infomative info .


Mike


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[Macroblock]

Could you record some video/audio to demonstrate the symptoms you are experiencing?

[Tripler]

Yes I can . I will do that tomorrow .
Thanks for the help guys

Mike

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[ZR2]

On a related note I just changed plugs on my 94. I bought it awhile ago, but had it in hiding from the wife for longer than normal. I changed plugs for the first time on this car and bought a few different sets. I pulled out some NGK Triex5 I think. I think an older plug of there. It was running fine but I am doing all the maintenance so I know where it is. I replaced these plugs with NGK Iridium plugs and ran fine for a few days then noticed a stumble turning into my driveway. Seems to stumble at times below 2000 rpm, more pronounced at 1000 to 1500. Idle didn't seem quite as smooth but after reading this analysis I might first change plugs, but also check pressure and fpr.

[Tripler]

I already have LGAFF CD but I can't find the dam thing . I bought that CD even before I got the car . It's here somewhere . Will keep looking or just buy another one . Completely forgot that I had it .

[Ccmano]

I already have LGAFF CD but I can't find the dam thing . I bought that CD even before I got the car . It's here somewhere . Will keep looking or just buy another one . Completely forgot that I had it .

Everything you need should be in your 1995 Factory Service Manual.
If I had one I could point you i the right direction.
H
:cheers:

[Tripler]

Everything you need should be in your 1995 Factory Service Manual.
If I had one I could point you i the right direction.
H
:cheers:


Oh ,, you mean the big read Books ! Yikes ... There a bit of a read indeed .

Will figure it out eventually . Not like we can go any where right now so in no rush .

Bugs me that I can't find the CD . It will pop up somewhere in the house one day

:-D

[Tripler]

Could you record some video/audio to demonstrate the symptoms you are experiencing?




Sorry , did not have time to do it . I will try make a vid tomorrow .
Hoping tapatalk lets me upload it .

:)

[Tripler]

Well I knew it . I finally found the LAGFF DVD set ... Hidden in an old briefcase .
;-)

[Macroblock]

I'm interested in hearing the engine to determine if all 8 cylinders are firing.

Did you verify that each HI-TENSION lead is providing a signal to its matching plug?
For example, if one coil is failing, 2 cylinders will go off-line.

Did you verify that each primary injector is getting a (-) signal from the ECM? One failing or partially failing injector or (-) signal to an injector will be very noticeable at low RPMs.

[Tripler]

I'm interested in hearing the engine to determine if all 8 cylinders are firing.



Did you verify that each HI-TENSION lead is providing a signal to its matching plug?

For example, if one coil is failing, 2 cylinders will go off-line.



Did you verify that each primary injector is getting a (-) signal from the ECM? One failing or partially failing injector or (-) signal to an injector will be very noticeable at low RPMs.Morning . Can you tell me what tools I need to do these tests ?
Lots to learn with these beasts indeed

Thanks

Mike


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[Tripler]

https://www.youtube.com/watch?v=fEXFfyRXUFY&feature=youtu.be


When the tac reaches 2500/2700 rpm the engine surges to 3000

https://www.youtube.com/watch?v=io-9ucGfg4I

[XfireZ51]

The fans turn on when u first start the car?

[Tripler]

The fans turn on when u first start the car?
No ,,, that's the garage AC running . Only thing I hear is the Vacuum pump and its very tight and only runs for a second or 2 . I found a huge leak underneath the plenum and had to mod the rubber connection with my previous plenum pull . .

[32valvZ]

At the risk of sounding silly, and Im not trying to be condescending, but I didnt see anywhere in the thread where you had replaced or at least ohmed out your ignition wires or checked your coils.. unless I missed it... just a suggestion..

[Tripler]

At the risk of sounding silly, and Im not trying to be condescending, but I didnt see anywhere in the thread where you had replaced or at least ohmed out your ignition wires or checked your coils.. unless I missed it... just a suggestion..Your not being silly sir . Pretty new to this . No I did not check the wiring and I have no experience as to how to do it . Learning as I go making lots of mistakes along the way .
Ordered more gaskets for a plenum pull . Getting pretty efficient at plenum pulls at least .
Looking into the emmisions first before another pull .
What equipment do I need to purchase to make sure the coils are working correctly .
Thanks for the input .
Lost without the help of you guys on this forum and Mr Haibeck


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[Tripler]

Just a quick list of what I have upgraded or changed so far .
New fuel filter , twice . First was full of rust so thought a second switch out would help grab any more crap.

Installed new serpentine belt

Found and fixed large vacuum leak under plenum

Installed a new IFPR

Installed new Accel Injectors

Installed new spark plugs

Car only gets High Octane non Ethanol Shell 91

That's the list so far

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[ZR2]

I have been reading / watching this thread with interest. Not trying to hijack it as I have a similar problem that has just emerged. Bought a 94 ZR1 awhile back and was stored for awhile, so I was doing maintenance, oil, plugs, filter etc. and after changing plugs noticed a stumble at low rpm's. Below 2000 was where it was happening. Car had NGK TR5IX plugs in it when I got it and I put in NGK BKR5EIX plugs and after about 50 to 100 miles the stumble started. It did not have a stumble with the original plugs, so I changed out the plugs this morning, they were a light gray to slightly white in color already, so I switched to a set of AC 41-800 plugs. I just came back from a short ride and the stumble is worse. I checked the fuel pressure on the engine and prior to starting it is basically 53lbs. I have waited awhile and it seems the pressure is holding, so I think the FPR is OK, I haven't changed the fuel filter yet and know I need to. Is it the heat range of the plugs possibly or probably a somewhat clogged fuel filter? Filter looks like a pain to change.

[XfireZ51]

ZR2,

So ur saying the motor had a ?stumble? or miss at idle w original plugs, then developed a stumble with the EIX and AC plugs? Is that on acceleration, or just cruise? The 405hp motors I believe were supposed to be gapped at .050? while the 90-92 were .035?. The 5 heat range may also be a bit hot especially if u r first sorting the motor out.
Need some more detail on the issue.

[Macroblock]

To check plug wires:

Method 1 is to use an inline spark plug tester. Test one lead at a time. Connect one end to the incoming HI-Tension lead, the other to GND (normally the other lead goes to the spark plug but this is likely not possible on the LT5 due to the deep plug shaft). The tester will light when high voltage comes down the wire as you turn the engine over. Available anywhere including Amazon. 2 testers cost under 25 dollars.

Method 2 involves removing one lead at a time and gently inserting a screwdriver completely into the boot of the HI-Tension lead (don't damage the connector). Place the driver over the plenum with about 1/4 - 1/8" of gap between the plenum and the metal part of the screw driver. Upon cranking, you should see a spark jump from the tool to the plenum.


BTW - Before buying any parts, this should have been your very first test. Let us know your results.

[Macroblock]

https://www.youtube.com/watch?v=fEXFfyRXUFY&feature=youtu.be


When the tac reaches 2500/2700 rpm the engine surges to 3000

https://www.youtube.com/watch?v=io-9ucGfg4I


Hmmm.....One cylinder could be off line due to fuel starvation. It could be an ECM issue since you've already changed the injectors.

After ruling out your ignition system by checking the HI-Tension leads, you might need to pull the plenum (again) and check your primary injector leads. Learn where cylinder 6 is.

Also - check out this thread:

https://www.zr1.net/forum/showthread.php?t=31783&page=1

[ZR2]

Macroblock, I am a different car and issue from the original thread starter. With the original plugs it did not have a stumble. I was updateing everything just doing my maintenance and when I replaced the plugs the 1st time with the NGK BKR5EIX plugs after about 50 to 100 miles I would say the car developed a low speed / low rpm stumble. Mainly at low rpms 1000 to 2000 maybe. nothing at higher rpms. Today I took out the plugs, yes #8 also, what a pain, and replaced them with some AC Delco 41-800 platinum plugs and sure enough the stumble was still there, but actually worse. I checked the fuel pressure after reading this current thread and it was at about 53 lbs with the rail pressurized but not started. It held to 30 lbs ish after 30 minutes or so. Car idles fine, just when a bit of load is put on it below 2000 it stumbles. I think the heat range of the NGK plugs was probably too hot by 1 or 2 ranges, but I think something else is going on. Car doesn't seem to be missing in the traditional way.

[ZR2]

Stumble is on acceleration not cruise. If I were cruising the car is fine, just under load.

[Macroblock]

Macroblock, I am a different car and issue from the original thread starter. With the original plugs it did not have a stumble. I was updateing everything just doing my maintenance and when I replaced the plugs the 1st time with the NGK BKR5EIX plugs after about 50 to 100 miles I would say the car developed a low speed / low rpm stumble. Mainly at low rpms 1000 to 2000 maybe. nothing at higher rpms. Today I took out the plugs, yes #8 also, what a pain, and replaced them with some AC Delco 41-800 platinum plugs and sure enough the stumble was still there, but actually worse. I checked the fuel pressure after reading this current thread and it was at about 53 lbs with the rail pressurized but not started. It held to 30 lbs ish after 30 minutes or so. Car idles fine, just when a bit of load is put on it below 2000 it stumbles. I think the heat range of the NGK plugs was probably too hot by 1 or 2 ranges, but I think something else is going on. Car doesn't seem to be missing in the traditional way.

Sounds like a cylinder or two are off-line. Any fault codes?

Verfiy the ignition leads as detailed in this thread. Afterwards, you will need to verify your injectors and/or the (-) feed to the injectors from the ECM.

[Tripler]

Thanks for the info guys . Yes , bad mechanic here . I had concerns doing a sparkplug screwdriver test might fry something so I never attempted that one
.
Thanks

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[lfalzarano]

You should encounter a stumble attempting full throttle at the lower RPMS you describe.

When these parameters are met: Coolant and Oil Temperature is 68F or above and System voltage is 10V or above Power Key on, and NO SES Codes, the ECM will signal the ports to open and wait for .5 second before turning on the secondary injectors at specific throttle vs, RPM. As the secondary injectors share the same drivers as that of the primaries, the pulse width signals are halved when the secondaries operate.
As shown in the diagrams (below), there are three different styles of driving which will operate the port throttles:
1. Ref. line A-B. Constant throttle position with a rising rpm. At the point the arrow crosses into the 'Port Throttle Opening Region' (top left shaded area) the port throttles open and the secondary injectors start firing.
2. Ref. line C-D. Constant rpm with increasing throttle position - logic as above.
3. Combination of the above: i.e. increasing throttle and rpm - logic as above.

The TXT attached file has the graphs of Throttle Position vs. RPM

My 90 stumbles slightly when I put my foot to the floor below 2000. Hope this helps.

[XfireZ51]

Lou,

Stock cal has a delay of .3sec.

[lfalzarano]

My iWatch runs a little bit faster:) Thanks for pointing that out.:handshak:

I pulled that tech info from the Corvette Forum.

[ZR2]

My stumble be a stumble ! !! Maybe coincidentally it was shortly after changing plugs. I did use some dielectric grease in the spark plug boots, which I normally don't do. Since it is non conductive I don't think that is an issue. Of course once I tested the fuel pressure the Schrader valve started to leak. I haven't looked at that but ?rdered a new valve. Need to get it sorted out as I love driving this thing. Just love shifting gears. I think I will do the fuel filter as I ran a substantial amount of cleaner through it last tankful. I was going to change it anyway, so I will change it and go from there .

[Tripler]

Did a spark test a few times actually to make sure and #8 is very weak compared to the rest . Found a way to get a spark tester hooked to the plug so all had a nice full colour accept #8 .
I removed the evaporator coil cover to get to #8 plug a lot easier and placed a cardbourd over the coil so not to bend the fins accidentally .


Mike

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[Macroblock]

ZR2 and Tripler - We gotta do process of elimination to narrow it down.


ZR2 - If you suspect it is a plug issue, you might want to remove one plug wire at a time and run the engine to isolate the cylinder that is possibly acting up. If you pull a wire off and there's no change in the idle, you've isolated the faulty cylinder.

Tripler - If #8 is suspect, pull the plug wire and run the engine. If the engine idle is not affected by 8 missing, likely something is amiss with 8.

Verifying the spark to all 8 cylinders is straightforward. Testing the injectors and the ECM transistor (-) drivers to the injectors is a bit tricky.

[Tripler]

ZR2 and Tripler - We gotta do process of elimination to narrow it down.





ZR2 - If you suspect it is a plug issue, you might want to remove one plug wire at a time and run the engine to isolate the cylinder that is possibly acting up. If you pull a wire off and there's no change in the idle, you've isolated the faulty cylinder.



Tripler - If #8 is suspect, pull the plug wire and run the engine. If the engine idle is not affected by 8 missing, likely something is amiss with 8.



Verifying the spark to all 8 cylinders is straightforward. Testing the injectors and the ECM transistor (-) drivers to the injectors is a bit tricky.Thankyou Macroblock . I will give that a shot tomorrow and let you know .

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[ZR2]

I agree. I have been redoing a house to get it on market for sale, so time wise I need to find the time. Of course when I tested the fuel pressure the other day to see if the FPR was acting up and if I had the proper pressure the schrader valve needle starting leaking........so I ordered a couple of them and some AC Delco plugs based on a few recommendations here. It is odd it happened after the plug change, but **** breaks I guess. I think what I will do is 1st change the fuel filter and see where I am. Then maybe check the plug wires by pulling off one at a time and see what happens. I got a feeling that this lovely motor want me to pull of the plenum and freshen her up with new injectors coils and wires etc.....but before her makeover I will see if the simpler items have any effect. I just gotta remember....Air......Fuel......and Spark. I had a 91 ZR1 that I bought from a dealer in Washington State. Thats what drinkin on a Friday night on E Bay can do for you.....ask me about shipping to the east coast!!!! He wasn't the most honest, it was on E bay about 4-5 years ago. It was a nice car, but it had bad secondary injectors, a few of the Bose speakers were blown and one of the Low Pressure Tire Sensors was always on, so I learned the hard way to take the plenum off and I replaced the injectors with FIC injectors. I did it 3 times in a matter of days......one time big vacuum leak, another time a big coolant leak and the 3rd time was the charm. Definitely ordered multiple gasket sets from Jerry's and the thicker plenum gaskets. It ran really hard once I was done. We'll See and I will report back in. Thanks for everyone's help in advance.

[Tripler]

Pulled the #8 plug wire and saw no difference when it was plugged in or not plugged in . #8 is kaputz I think .


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[Macroblock]

Tripler - sounds like cylinder #8 is off-line. Its waste-spark partner is cylinder #5, so try the test by removing that Hi-Tension lead to see if doing so has any affect.

If #5 and #8, together or one at a time, have no affect on engine idle, then it could be an ignition coil, the ignition module or the wiring between the two.

If only 8 has no affect on idle, then it's possible the primary injector at #8 is not pulsing. This could be a faulty injector, the ECM or the wiring in between.

[Tripler]

Tripler - sounds like cylinder #8 is off-line. Its waste-spark partner is cylinder #5, so try the test by removing that Hi-Tension lead to see if doing so has any affect.



If #5 and #8, together or one at a time, have no affect on engine idle, then it could be an ignition coil, the ignition module or the wiring between the two.



If only 8 has no affect on idle, then it's possible the primary injector at #8 is not pulsing. This could be a faulty injector, the ECM or the wiring in between.Pulled #8 and #5 at the same time and it idles ruff and sounds the same .


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[Tripler]

Also someone had asked before if the fans were running when I start the car and I confirmed today that they do not run on startup

;-)

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[Macroblock]

Pulled #8 and #5 at the same time and it idles ruff and sounds the same .

To double check, start and run the engine with 5 and 8 disconnected. Connect 5 and note any changes in idle. Connect 8 and note any changes in idle.

If connecting 5 and 8 didn't have any affect, it's pointing to an ignition problem. Perhaps a coil or the Ignition Module (DIS).

Sounds like you'll need to pull the plenum to test and repair further.

With the plenum off you can test the ECM (-) outputs to the injectors. A couple of noid ("solonoid") lights will come in handy for this. A basic 12v test light will be needed to simulate a Crank Hi signal to spoof the Ignition Module and ECM.

Let us know when you have the plenum off.

[32valvZ]

5 & 8 are the same coil... seems like that might be the problem

[Tripler]

To double check, start and run the engine with 5 and 8 disconnected. Connect 5 and note any changes in idle. Connect 8 and note any changes in idle.

If connecting 5 and 8 didn't have any affect, it's pointing to an ignition problem. Perhaps a coil or the Ignition Module (DIS).

Sounds like you'll need to pull the plenum to test and repair further.

With the plenum off you can test the ECM (-) outputs to the injectors. A couple of noid ("solonoid") lights will come in handy for this. A basic 12v test light will be needed to simulate a Crank Hi signal to spoof the Ignition Module and ECM.

Let us know when you have the plenum off.


I fully expected to pull the plenum again . Will keep you updated .


;-)

[Macroblock]

5 & 8 are the same coil... seems like that might be the problem

Yup sounds like it - unless the Hi-Tension lead going to #8 is the issue. Perhaps the lead is creating high resistance or shorting to ground.

[XfireZ51]

You can take a look at my thread on chasing knock. If u go here, you can see what you may want to check for regarding ur coils.

http://www.zr1.net/forum/showpost.php?p=310348&postcount=16

[Tripler]

You can take a look at my thread on chasing knock. If u go here, you can see what you may want to check for regarding ur coils.



http://www.zr1.net/forum/showpost.php?p=310348&postcount=16Wow, thanks for that . Very interesting .
Since the coils are 25+ years old I will switch those out first with new wires and plugs . If it still idles ruff and has no power then back to checking more bits .
I will need a bit of instruction on how to test the injector cables to make sure they are putting the right amount of voltage to the injector .

Thanks



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[Tripler]

I got the plenum off again . What are the steps to test the Coils .
Thanks


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[Macroblock]

Wow, thanks for that . Very interesting .
Since the coils are 25+ years old I will switch those out first with new wires and plugs . If it still idles ruff and has no power then back to checking more bits .
I will need a bit of instruction on how to test the injector cables to make sure they are putting the right amount of voltage to the injector .


Yes, good idea to change the ignition coils and perhaps the hi-tension leads while you have the plenum off.

The coils are all the same so if you want to test for the sake of testing you could exchange the coil that serves 5 and 8 with another coil and see if this moves the symptom to another cylinder pair.

If the problem moves, it's likely the coil but if it remains on 5 and 8, the problem could be a bad hi-tension lead or leads, bad plug or plugs or an issue with the Ignition Module.

-----------------

To test the ECM and injectors with the plenum off you will require a test light and at least one 'noid' light.

Put the key to "ON". Connect the test light alligator clip to the battery (+) and quickly and repeatedly connect and disconnect the probe end to the Crankshaft HIGH pin on the Ignition Module Test Port.

Pulsing a signal to the Crankshaft High line will spoof the ECM into thinking you are making a start attempt (i.e. <400 RPM). You will notice the fuel pumps come to life and a few other devices. All primary injectors will fire at the same time.

Now disconnect all the primary injectors. Put a 'noid' light on each injector connector or do one connector at a time if you only have one 'noid'. Spoof the ECM again and verify that each primary circuit lights up the noid.

Note 1 - The ECM output to each injector is (-).
Note 2 - If you don't have a 'noid' light a test light can be substituted.
Note 3 - Link to image of Ignition Module Test Port:
http://www.zr1ecm.com/img/blog/details/DIS_TEST_PORT.jpg

http://www.zr1ecm.com/img/blog/details/DIS_TEST_PORT.jpg

[XfireZ51]

Here?s a good thread re: checking coil packs.

http://zr1.net/forum/showthread.php?t=31890&highlight=Testing+ignition+coils

[Tripler]

Shame the forum does not have a thumbs up option because I would really like to thumb up everyones posts . Extremely helpful . I have never heard of noids before lol but I see I can buy them here at our Canadian tire . On Monday I will check the ohm readings on the coils and attempt a test of injector electrical leads .

Thanks for that pic of the service module plug and coil ohm info


Thumbs Up

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[WARP TEN]

Shame the forum does not have a thumbs up option because I would really like to thumb up everyones posts . Extremely helpful . I have never heard of noids before lol but I see I can buy them here at our Canadian tire . On Monday I will check the ohm readings on the coils and attempt a test of injector electrical leads .

Thanks for that pic of the service module plug and coil ohm info


Thumbs Up

Sent from my SM-A205W using Tapatalk

Let me second the need for a Thumbs up or Like button. I have liked those on all the other forums; maybe this is another symptom of the aging vBulletin sites. Any way to add this feature to our existing forum site? --Bob

[Ccmano]

Let me second the need for a Thumbs up or Like button. I have liked those on all the other forums; maybe this is another symptom of the aging vBulletin sites. Any way to add this feature to our existing forum site? --Bob

Not a bad idea. I have put in a request. Keep in mind we are limited to forum capabilities which are out of our hands.

Of course you can simply use an emoji from the Selection to the right of the message box when you write the post.

:thumbsup:

H
:cheers:

[WARP TEN]

Not a bad idea. I have put in a request. Keep in mind we are limited to forum capabilities which are out of our hands.

Of course you can simply use an emoji from the Selection to the right of the message box when you write the post.

:thumbsup:

H
:cheers:

Thanks Hans. I realize some things are out of your control and some just can't be done with a specific platform. --Bob

[Tripler]

Found 2 coils that have zero ohms readings and the other 2 work fine . Ordered 4 new from Corvette Depot .
There on back order so a few weeks to receive them .


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[Tripler]

Did the noid test . All primary injectors lit up .
[emoji106]

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[Macroblock]

Did the noid test . All primary injectors lit up .
[emoji106]


Awesome - Great Job!:thumbsup:

[Tripler]

Awesome - Great Job![emoji106]Thanks Mac [emoji106] . Is there any other tests I need to do ?


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[Macroblock]

Tripler - it sounds like you narrowed it down to an ignition issue. Once you replace the coils and reassemble the plenum, you'll be able to test.

Coils that are not providing adequate voltage are a sign of trouble and will cause the driveability issue you describe.

[Tripler]

I am hoping that's all it is . I have replaced all the 25 year old bits that needed upgrades so far and I sure am looking forward to putting it back together . Again a huge thank you and thumbs up ...



[emoji106][emoji846]

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[Macroblock]

No sweat. Let us know how you make out.

[Tripler]

Just got the new set of ignition coils . 2 of the packages had the orange replacement rubber seal that sits under the coil on the ignition module . Do I need to replace them or am I ok to use the originals because I only have 2 replacements .
Thanks

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[XfireZ51]

U should be ok. Use the ones from the good coils just for a bit of margin.

[Tripler]

U should be ok. Use the ones from the good coils just for a bit of margin.I called the supplier but won't know until Tuesday if they will send the 2 missing grommets. Would like to have new if possible . I can wait a little longer if I have too and then original ones actually look good and are still soft and not gotten brittle being 25 years old or more .
Thanks

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[Tripler]

Up and running again . Idle is smooth . Sounds really good so far . Taking it for a test drive tomorrow .
Thanks again for all the help trouble shooting the trouble [emoji16].
Ride tomorrow will show if it's working correctly.
[emoji846]

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[dredgeguy]

Well done Mike, you stuck with it and sure that you have solved the problem!

[Tripler]

Well done Mike, you stuck with it and sure that you have solved the problem!Thanks Charlie . Tomorrow will tell the tale .
Looking forward to the test drive . Weather looks good with cool air temperatures so the Z is gonna enjoy that [emoji1]

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[Tripler]

Well scratch the drive tomorrow . My dog just got nailed by a skunk . Jumped in the bath with her to try the tomatoes juice trick . Whole house stinks including me because I had to pick her up and pull her off the skunk .
Not getting in the Z with this smell on me lol . Sitting up all night with her . Locked her in the front foyer with a baby gate . Poor thing . Spray got in her eyes .
Her name is Pogo by the way and she is a Beagle/ Whippet mix .
Tapatalk wont let me upload photos anymore
[emoji19]

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[BigJohn]

Well scratch the drive tomorrow . My dog just got nailed by a skunk . Jumped in the bath with her to try the tomatoes juice trick . Whole house stinks including me because I had to pick her up and pull her off the skunk .
Not getting in the Z with this smell on me lol . Sitting up all night with her . Locked her in the front foyer with a baby gate . Poor thing . Spray got in her eyes .
Her name is Pogo by the way and she is a Beagle/ Whippet mix .
Tapatalk wont let me upload photos anymore
[emoji19]

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I have been skunked before it takes about two weeks to wear off!

:-x

[jss06c6]

We've got two Jack Russell's that can't pass on any opportunities to "Hunt", no matter the consequences!

Use Dawn soap (cuts the oil) and baking soda. It's the oil you need to get rid of. Anything you touched in the house is now contaminated! May require professional cleaning or replacement (personal experience!)

Great news on the coils! I had same on my '91! Stumbled under load..

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[Mystic ZR-1]

I have been skunked before it takes about two weeks to wear off!

:-x

You're not coming to coffee tomorrow smelling
like that are you?

[BigJohn]

You're not coming to coffee tomorrow smelling
like that are you?

I still have the stripes, but the odor is long gone!

:thumbsup:

[Tripler]

OMG LOL . Ya , skunks are great fun . You know they smell better when you run them over compared to this . Smells like ABS plastic pipe burning .
Anyway , took the beast for a short tear anyway to gas it up and Holy Mackerel ! W O W . What a difference . Rear wheels keep braking loose too easily and with the ASR engaged ! [emoji16][emoji38][emoji1][emoji2][emoji3][emoji39]
What a thrill to drive one of these Beauties ! Motor smooth as smooth can be . No stumble , just get up and go . Sweet !

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[Tripler]

Huge thanks to everyone's input , ideas , hunches and facts .
Another huge Thankyou to Marc Haibecks help and support and also to his awesome Plenum Pull and Injector Replacement Video . I watched it multiple times and kept the labtop close to double check proper procedures and checklists .
I would have been completely lost without it .
But I do have one issue . Everytime I turn the lights off , the headlight motors reset themsleve every time . Never did that before other than when the battery is reconnected.
Thanks
Mike


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[Rodder]

For me when going parking light on/off and had one headlight motor run it was the headlight gears. Failed totally shortly after. It also could drain the battery in just a few days. But both sides run for you, sounds unusual both go bad at once. Do the manual knob work normally? Otherwise its gears for sure.

[DRM500RUBYZR-1]

Pellets, Pellets, and Pellets.
A $20.00 fix.
:cheers:
Marty

[ZR2]

I had accidentally interrupted this thread in the middle with my hesitation issues and apologize, but have been following it and with some advice here and just some old school stuff finally got around to looking into my stumbling / hesitation issues. If felt like an old fashion mis and so I hooked up my timing light to each plug wire. Been awhile since I had t he timing light out. I went down the line up with cylinder 1 first then 2 etc. Sure enough once I got to plug 5 the light started shuddering, not the constant pulsed flash of the first two cylinders. I kept going and sure enough 8 was acting the same way. So upon some research the WSM etc. I saw that it is the same coil that sparks both cylinders, so pretty sure I found my issue. I haven't started to start the operation yet, but have all new coils and wires and also decided to splurge and get new FIC injectors. I had used them previously on a 91 ZR1 I had and was really happy with the response. I am looking forward to getting started, It has been too long.

[DRM500RUBYZR-1]

I had accidentally interrupted this thread in the middle with my hesitation issues and apologize, but have been following it and with some advice here and just some old school stuff finally got around to looking into my stumbling / hesitation issues. If felt like an old fashion mis and so I hooked up my timing light to each plug wire. Been awhile since I had t he timing light out. I went down the line up with cylinder 1 first then 2 etc. Sure enough once I got to plug 5 the light started shuddering, not the constant pulsed flash of the first two cylinders. I kept going and sure enough 8 was acting the same way. So upon some research the WSM etc. I saw that it is the same coil that sparks both cylinders, so pretty sure I found my issue. I haven't started to start the operation yet, but have all new coils and wires and also decided to splurge and get new FIC injectors. I had used them previously on a 91 ZR1 I had and was really happy with the response. I am looking forward to getting started, It has been too long.


WHAT?

Are you some kind of heathen or anarchist?

How can you possibly diagnose such a thing without the latest wiz-bang Scanner costing upwards of $10,000.00?

Good Job!!!

I chuckle when I see one of my techs pulling individual spark plug wires and evaluating what effect, if any, each has on the running engine.

Some things that you learn as a kid, fortunately stay with you throughout your life.

When young, I wished I had access to a then "state of the art" Sun Distributor Analyzer.
When the"old mechanic" asked me what I needed that for, he reached into his tool box and pulled out a box of distributor advance weights and springs.
He instructed me to grab my timing light.
Over the next hour of trying various combinations and observing changes in the timing with the light, we "curved" my distributor the old fashioned way.
For years he had me keep fresh match book covers and a new set of points in my glove compartment so that I could do "Super-Tuning" whenever needed.

My ear can still tell how many turns a mixture screw needs.

Kind of neat with all of the welcome technological advances, some old tried and true methods still get you to the same place.

Now get Mark's DVD and tackle that plenum pull and replace those coils!

Keep us posted with your progress!
:cheers:
Marty

[ZR2]

Marty, so funny that you say old school. I did start the pull this morning before my lovely wife.......well needed help well say. I have had many carburetor cars and yes I agree pretty easy.....screw the mixture screw in until it stumbles and then back it out a 1/4 to 1/2 turn. Funny you talk about the distributor and using the different weights etc. I had a 71 454 LS5 corvette, which i redid the car pretty completely over about a year and it was the 1st Big Block I rebuilt. I built it similar to an LS6 but with a hydraulic cam and roller tipped rockers. I put an MSD Distributor and Box on it, but still used my fancy timing light to adjust the base timing and advance with different weights etc. I had the notes in my timing light box before I started this morning. The car had a Rochester 4 barrel on it which I tried to rebuild and it just wasn't right. I admitted defeat......but had a guy he was about 70 at the time and all he did was rebuild carbs. He had a 40 year old Holly flow machine. He rebuilt it for me for $130. He told me to stick with doing mortgages!!!! Once I put that carb on, it had a 100 more horsepower or so it felt. It would bust loose the tires loose at 25 mph in 1st gear with 3:36 gears. I have moved on to the ZR1. I had a 91 in the past and missed it. Before I owned it I didn't care as much for the C4, but once I owned it, my opinion changed and I love it.

[DRM500RUBYZR-1]

Those lessons learned on the 454 will serve you well, still!
I was a banker for 40 years, Now I have even more fun!
We are here to help you all; Just ask!
:cheers:
Marty

[Tripler]

For me when going parking light on/off and had one headlight motor run it was the headlight gears. Failed totally shortly after. It also could drain the battery in just a few days. But both sides run for you, sounds unusual both go bad at once. Do the manual knob work normally? Otherwise its gears for sure.


Thanks for the tip . I have not had time to hand crank them yet but will try that this week . Just the right side resets itself after lights turn on then off . Weird . Did not do that before .
;)

[Tripler]

BEFORE
https://www.youtube.com/watch?v=ekfA___S-U4&feature=youtu.be

AFTER
https://www.youtube.com/watch?v=8FHbNq-RT4k&feature=youtu.be