Plenum Pull...Parts List Varification...

[| 1990 ZR-1 |]

I have a MY 90 with 33k miles. I'm having a similar issue as ZR1Man where I can't fill much of a differnece, if any, between Normal and Power settings. I do get a little bit of vibration and struggle as the RPM's rise with the Power Key on. The engine seems smoother with Normal setting, but the accellaration is the same in both settings. I already tested the secondary actuators per Marc H's instructions and they work fine. My assumption is that at WOT the secondary intakes open, and there's extra air going in, but not fuel. Please correct me if I'm wrong.

I belive the car is completely original under the plenum judging by the ammount of dirt and grime piled up in there over 21 years. I would like to pull the plenum and replace most of the serviceable items, and I wanted to verify the list I gathered from reading in different posts here.

1. New injectors qty 16 FIC or Accel
2. Gasket/Seal Kit (36pcs) from Jerry, Fuel Injector Maint, 90~92 (VITON)
3. Wire Set, Spark Plug, 90~95 [10D] form Jerry
4. Duralast/Ignition Coils from Autozone Part # DC-63
5. Ngk Ix Iridium/Spark Plug Part # BKR5EIX-11
6. Fuel Filter from Ecklers Part # GF652
7. Coolant and Oil Change

Am I missing anything? If anyone experienced any issues with the parts above or if you have a suggestion for better parts, please feel free to share.

I can't wait to feel the power of this beast once it's properly running. It feels quick at Normal setting, and to think how much faster it could be with the additional almost 200 hp is scary!!

As always, I greatly appreciate the help of this community.

-Gary

[Kevin]

just make sure you don't use dexcool for the coolant. i mean, unless you want to pop a head gasket...

[tomtom72]

Looking great with the list!

Just be sure that the coils are by application. I went with the AC Delco coils only because that coil type has a few applications. GM has a specific P/N for the LT5 coil due to it's placement on the motor.

The plugs are a personal choice. Remember that the 90's have flat seats in the plug holes and use a washer. You can use a taper seat, precious metal plug but you have to over T/Q it to create a tapered seat. I stuck with the AC Delco 41-602's as they are the replacement by application for the FR2LS's, flat seat w/washer.

This is just MHO.:o

:cheers:
Tom

Yes on the coolant 1825-M spec is the GM spec number, P/N 12378560. Use a GM T-stat also! If you have to buy other coolant, make sure on the label it says "Do Not Mix with DEXCOOL" or "Do Not Use in a cooling system requiring DEXCOOL." that's a dead give away that it's 1825-M GM spec coolant.

[QB93Z]

I suggest that you trouble shoot a secondary throttle vacuum system fault so that you know if you have to look for vacuum leaks when you have the plenum off.

Here is a link to zr1man's similar hread: http://zr1.net/forum/showthread.php?t=14438

There are a couple of common leak sources under the plenum. One is a check valve and the other is the Secondary Throttles Solenoid valve. It is easy to see if the check valve is leaking without pulling the plenum.

But first, verify that your vacuum pump is operational.

Jim

[tccrab]

I suggest that you trouble shoot a secondary throttle vacuum system fault so that you know if you have to look for vacuum leaks when you have the plenum off.

Here is a link to zr1man's similar hread: http://zr1.net/forum/showthread.php?t=14438

There are a couple of common leak sources under the plenum. One is a check valve and the other is the Secondary Throttles Solenoid valve. It is easy to see if the check valve is leaking without pulling the plenum.

But first, verify that your vacuum pump is operational.

Jim

Further to this suggestion, here's a link that every ZR1 owner should have handy:
http://www.corvetteactioncenter.com/forums/c4-corvette-zr-1/14272-1990-1995-zr-1-secondary-port-vacuum-diagnosis.html
Props to Rob of the Corvette Action Center for his comprehensive write up on the ZR1 secondary port system.

While you're in there cleaning and poking around, be sure to re-torque all the fasteners on the oil mist boxes and the injector housings. They tend to loosen with repeated temperature cycles.


TomC
'Crabs

[| 1990 ZR-1 |]

Looking great with the list!

Just be sure that the coils are by application. I went with the AC Delco coils only because that coil type has a few applications. GM has a specific P/N for the LT5 coil due to it's placement on the motor.

The plugs are a personal choice. Remember that the 90's have flat seats in the plug holes and use a washer. You can use a taper seat, precious metal plug but you have to over T/Q it to create a tapered seat. I stuck with the AC Delco 41-602's as they are the replacement by application for the FR2LS's, flat seat w/washer.

This is just MHO.:o

:cheers:
Tom

Yes on the coolant 1825-M spec is the GM spec number, P/N 12378560. Use a GM T-stat also! If you have to buy other coolant, make sure on the label it says "Do Not Mix with DEXCOOL" or "Do Not Use in a cooling system requiring DEXCOOL." that's a dead give away that it's 1825-M GM spec coolant.
Thanks for the input Tom.
I see that Autozone sells the AC Delso 41-602 spark plugs, but how come they don't come up under the ZR-1 option?

Also, where can I buy the AC Delco coils? Are you sayind that theDuralst coils will not work on LT5?

[| 1990 ZR-1 |]

Further to this suggestion, here's a link that every ZR1 owner should have handy:
http://www.corvetteactioncenter.com/forums/c4-corvette-zr-1/14272-1990-1995-zr-1-secondary-port-vacuum-diagnosis.html
Props to Rob of the Corvette Action Center for his comprehensive write up on the ZR1 secondary port While you're in there cleaning and poking around, be sure to re-torque all the fasteners on the oil mist boxes and the injector housings. They tend to loosen with repeated temperature cycles.


TomC
'Crabs
Jim and TomC.

I checked the vacum pump, and it works fine. I also hooked up a vacum pump to the vacum line going under the plenum, and pumped it to 10ng. The pressure held for a while, but did go down to zero over a period of 10 minutes. Also when turning on the ignition, the pump comes on for a few seconds than shuts off, but than after about 3-4 minutes pumps again for about a second. I think i have a slow vacum leak which probobly will not affect the operation of the secondary vavles as much, but I will certainly try to trace it and fix it while i'm under there. How long does the pressure normally hold for in a properly working system?

[mike100]

Jim and TomC.

I checked the vacuum pump, and it works fine. I also hooked up a vacum pump to the vacum line going under the plenum, and pumped it to 10ng. The pressure held for a while, but did go down to zero over a period of 10 minutes. Also when turning on the ignition, the pump comes on for a few seconds than shuts off, but than after about 3-4 minutes pumps again for about a second. I think i have a slow vacum leak which probobly will not affect the operation of the secondary vavles as much, but I will certainly try to trace it and fix it while i'm under there. How long does the pressure normally hold for in a properly working system?

my vac pump cycles a couple of times every min or two- I think that's normal...it actually leaks at the pump hose I think. All of my stuff was tip top, except for 1 vac line had popped off. On yours, perhaps the solenoid that runs the secondaries is stuffed, but at anyrate, you will be able to diagnose everything quite easily once you pull the thing apart.

Even though my problem was simple, further repairs included replacing the injectors. That really made it run a lot smoother.

I used the parts store non-platinum Ac plugs- they run fine. Since plugs are so easy to change on the LT5, I decided against exoticly expensive ones...plus I wanted as close to the factory heat range for emissions testing.

Don't know about the coils, never replaced anything on mine..pretty standard GM part though.

A bad injector coil will manifest itself as a miss when warm, but your original problems sounds like an issue with the secondary injector relay or something electrical with the driver.

[| 1990 ZR-1 |]

Given that I only have 33k miles on the car, do I really need to replace the wires and the coils? Do they go bad due to age or miliage or both? I don't really have any missfiring issues, but I figured since I'll be under there already, might as well replace everythign that could potentially give me trouble down the line.

[tomtom72]

Gary, I'm not saying that your choice of coils is incorrect. Rather, the issue as I see it is that type of coil has a few GM applications. GM lists two coil types for a waste spark application, ours specifically and then another coil P/N for all the other GM applications. Upon closer reading one finds that "all others" live in the open air, ours live under the plenum & have a different P/N. My conclusion is that ours live in a more severe environment therefore they must be constructed to tolerate the conditions.

Also, a long time ago it was popular to use Screaming Demon Coils for the extra juice. The long term issues that I observed was that the failure rate was higher than the OE coils. Is there a correlation? I don't know. I just feel it is worth mentioning as a fwiw. I had Accels in my car for 3 yrs and they didn't miss a beat, I switched them out the the correct GM ones because the Accels had other applications besides an LT5. My thought was are these built to survive under the plenum and can be used in other applications; or is the LT5 application the "other" or "also fits" application?

:cheers:
Tom

[Jim Nolan]

If you are putting that much into it then replace the wires. There is no sense going into it later when it can be done now. On another note check the torque on the injector housing bolts. The first time I took mine off half of them were finger tight. It's my understanding this is common.

[tomtom72]

Okay, my two cents on wires. They are basically carbon core RF wires. Consider the environment of an LT5. I r&r'ed mine at the 15k mark because I had to do injectors. I found a deal on Magnecore 10mm wires on e-bay for about half price so I bought them. :o

Was that a good choice? I don't know, Honestly it was proly a waste of $140.00 as I'm sure the GM replacement wires would do just fine. It's the environment and the material's reaction to the environment more than just time or mileage in MHO.

My spark plug choice is based on GM said that the 41-602 plug crosses to a FR2LS plug which is NLA, and the FR2LS plugs came from BG in my car.....Besides Pete says that they work just fine in his 10 second ZR-1....so I guess they would work just fine in my slow, stock ZR-1.... and at the price I can afford to change them every year! :mrgreen:

:cheers:
Tom

[| 1990 ZR-1 |]

Thanks guys. I'm sold on the spark plugs, and will replace the wires and coils too.

Any idea where i can buy the LT5 specific GM coils?
Also, any issues going with the wires form Jerry's?

[mike100]

I'm decided to reuse my stock ignition. 27k miles and only the plugs are new. It all works fine.

I'm going to either use my plug wires up, or the car will stay low mileage original- either way, it was less money out of pocket.

[| 1990 ZR-1 |]

I'm decided to reuse my stock ignition. 27k miles and only the plugs are new. It all works fine.

I'm going to either use my plug wires up, or the car will stay low mileage original- either way, it was less money out of pocket.

That's kind of what I'm shooting for. The will stay low milage and will only be driven on nice weekends.

[| 1990 ZR-1 |]

Quick update. I just had a chance to measure the restitatnce of both the primary and secondary injectors after getting the car to it's opreational temperature range by running it for 30 minutes.

Here's the readout.
Primary:
#6 - 13.8
#5 - 13.8
#7 - 13.7
#2 - 13.8
#1 - 13.8
#8 - 13.6
#4 - 13.7
#3 - 13.9

Secondary:
#6 - 15.1
#5 - 13.4
#7 - 13.5
#2 - 13.6
#1 - 13.5
#8 - 13.4
#4 - 13.6
#3 - 13.6

With the exception of Cylinder # 6 Secondary injector reading a little high, I belive everythgin else is well within the norm.

My secondary vacum pump works fine, and the vacum pressure under the plenum alos holds fine. The secondary intake acuators are operational.

Given the above info, what else should I trouble shoot?

[mike100]

Have a look at this video:
You tube secondary injector diagnostic vid (http://www.youtube.com/watch?v=RkKfoA7LSR8)

I actually purchased a tech1A- it's so handy for the OBD1 cars.

while your in there, check out a number of other vids from the same guy- some neat Corvette stuff (like the LT5 engine dyno runs.

I

[mike100]

It does sound like you might have an ignition problem, but if you still have the orig 1990 multec injectors, you should probably replace them anyhow. I'd also read the section on the secondary injector relays to get an idea of how they work.

[tomtom72]

Okay Gary, at this point I have to figure the coils passed the ohm test. So what's left?

2* drivers ( relays ) and 2* fuel pump, and the power switch.

The "Full Engine Power" light stays illuminated when the switch is turned to the Full Power position, right? I know that sounds odd, but on the 90's the contacts in our switches seem to have age issues. If the FEP light in the DIC is not illuminated when the switch is in the full power position there is no 2* operation.

The 2* fuel pump needs to be working also. You did the KOEO fuel pump test, right?

I'll have to look up the diagnostic chart for the 2* relays.....but I think if you read the ohms on the 2* injector coils then the 2* relays ( drivers or quad drivers as they are sometimes called ) are okay. I'm not 100% so I'll look in my FSM.

You do not get a SES light in the DIC when she starts to stumble, right?

:cheers:
Tom

This is a P.S. because I always forget this item. The secondary MAP sensor under the ECM bracket. That has to work also however a bad 2* MAP sets a DTC, I can't remember which for sure. I'll go look & check back with you. Sorry.

[tomtom72]

I did some checking in the FSM. I think I'm correct in thinking the the 2* injector relays are okay as you did get ohm readings. Also, the 2* MAP is okay as you didn't indicate any SES light, either steady or flickering and you didn't mention that the car stops at 3,000 rpms, that's a DTC 61. No DTC 61 eliminates the secondary vacuum system in it's entirety the way I read the diagnostic chart. I could be wrong on that though.

Therefore, I think a look see at the spark plugs is in order to see the mixture condition. Also, the fuel pump test is also a useful diagnostic tool at this point, the KOEO test. You could have some one rev the car and go stand & smell the exhaust to see if it's lean, but then you still would need the fuel pump test. Unless the 2* injector tips a blocked solid with crud I can't see what's wrong if the fuel pumps pass the test.

:cheers:
Tom

[A26B]

What about the valet key? Isn't there so e history withthe early valey key switch not making contact?

Nothing he is telling us regarding symptoms, really points to a miss. vacuum system is good, no codes, no noticeable miss, just no secondary power difference. soinds like the valet key to me.

[| 1990 ZR-1 |]

I did some checking in the FSM. I think I'm correct in thinking the the 2* injector relays are okay as you did get ohm readings. Also, the 2* MAP is okay as you didn't indicate any SES light, either steady or flickering and you didn't mention that the car stops at 3,000 rpms, that's a DTC 61. No DTC 61 eliminates the secondary vacuum system in it's entirety the way I read the diagnostic chart. I could be wrong on that though.

Therefore, I think a look see at the spark plugs is in order to see the mixture condition. Also, the fuel pump test is also a useful diagnostic tool at this point, the KOEO test. You could have some one rev the car and go stand & smell the exhaust to see if it's lean, but then you still would need the fuel pump test. Unless the 2* injector tips a blocked solid with crud I can't see what's wrong if the fuel pumps pass the test.

:cheers:
Tom

Tom thanks for the thorough repose. Here are some answers to your questions. The SES light is not eliminated at all while the car is idling or under load, and I know it?s functional because it comes on when key is on. I had to unplug the connectors from the secondary injector relays in order to get the resistance reading, so I can?t really tell if the relays are functional. The FEP light comes on with the valet key and stays on. It does not flicker at all even when I jiggle the key.
This morning I started her up, and right away I noticed she was idling rough. The engine was vibrating more than normal, and there was also a strange clicking sounds coming from the right side of the engine and a knocking sounds from under the engine. I?m assuming this is due to the misfire. I took her out for a spin, and she definitely did not run normal. Felt like a misfire. A lot of vibration was coming through the steering wheel. The vacuum seems to be okay. I also pulled all the plugs, and they seemed fine. I replaced them and the fuel filter today. I also bought a fuel pressure gauge, and the pressure while idling read 43 psi and about 50psi at WOT. Is this within the norm? I went through the whole car with a fine comb thinking maybe I knocked out a connector, or a wire, or a vacuum hose, but everything seems to be where it belongs. Now she ran fine in the normal mode prior to this, and the only thing that I?ve done to her since the last time I drove it was measure the resistance of the primary and secondary injectors, and the check the secondary actuators by shorting pin c17. I?m puzzled as to why this would cause a misfire unless it?s a coincidence and one of the injectors went bad. I did, however, measure the resistance of the primary injectors again, and they all read between 13.6 to 13.8 ohms which is within the norm. Any thoughts?

[mike100]

My injectors ran worse with heat soak, but 4 of them read low ohms (one was even 6 ohms). It's almost a given that your injectors are suspect if they are indeed originals- I'd plan on doing that anyhow.

the knock is the dual mass flywheel having fits. it will go away when you find the problem.

[tomtom72]

Okay now we're getting some where! Very good reporting of symptoms so now we have something to kick around. Mike has it in a short version.:icon_thum

Now here is the long winded version.:blahblah: :o

The strange "clicking" from the right side is/are the 1* injectors firing but no gas is coming out. The gas cushions the sound of the mechanical bits. Therefore my guess is right side 1* are not allowing gas in from the fuel rail, ......or every spark plug on that side of the motor is cracked and arching against the head which I doubt.

Second, the clanking from "under" the motor is the Dual Mass flywheel reacting to the uneven power pulses and it makes that noise as it reacts to miss-fires or dead cylinders.

My humble conclusion is the OEM injectors are on there way to injector heaven. However, two more tests .... sorry, but this is what I would do as I'm new to computer cars & EFI! Pull the plugs and compare left to right bank. The ones not getting fuel will look cleaner than the ones getting fuel. Idle the car and go stand behind at the exhaust pipes and get a good nose full of the exhaust. Does it burn your nose and eyes? If yes that is a lean condition you smell, which points back to the 1* injectors not passing fuel. The exhaust smoke should be a fairly white vapor from the leanest side and the richer side will be darker & smell rich.

If at this point you have a scanner & plug in you will see that the fuel #'s are nuts as the ECM tries to add more fuel in response to the O2 sensors' feedback info. The scan at first looks like the motor is rich, but it's not because the scanner only sees the ECM's reaction to the O2 feedback, lean, and tries to add fuel. Anyway, if there are some primaries that don't work, the secondaries can't make up for it when they come on line. Hence the poor mid range and top end performance. The vibration thing is my tell tale as it's looking like a lean miss from where I sit. If I was there I'd do my smell test and use my scanner.

Next, I'm not all that happy with the fuel system's PSI readings, but with 21 year old pumps what do you expect. I would consider doing r&r on the pumps & socks later. The readings are on the low side of the FSM range. Oh, if you don't have one yet, please do look to buy a FSM at Heliminc.com....the best tool you can have in the box!

:cheers:
Tom

[| 1990 ZR-1 |]

Okay now we're getting some where! Very good reporting of symptoms so now we have something to kick around. Mike has it in a short version.:icon_thum

Now here is the long winded version.:blahblah: :o

The strange "clicking" from the right side is/are the 1* injectors firing but no gas is coming out. The gas cushions the sound of the mechanical bits. Therefore my guess is right side 1* are not allowing gas in from the fuel rail, ......or every spark plug on that side of the motor is cracked and arching against the head which I doubt.

Second, the clanking from "under" the motor is the Dual Mass flywheel reacting to the uneven power pulses and it makes that noise as it reacts to miss-fires or dead cylinders.

My humble conclusion is the OEM injectors are on there way to injector heaven. However, two more tests .... sorry, but this is what I would do as I'm new to computer cars & EFI! Pull the plugs and compare left to right bank. The ones not getting fuel will look cleaner than the ones getting fuel. Idle the car and go stand behind at the exhaust pipes and get a good nose full of the exhaust. Does it burn your nose and eyes? If yes that is a lean condition you smell, which points back to the 1* injectors not passing fuel. The exhaust smoke should be a fairly white vapor from the leanest side and the richer side will be darker & smell rich.

If at this point you have a scanner & plug in you will see that the fuel #'s are nuts as the ECM tries to add more fuel in response to the O2 sensors' feedback info. The scan at first looks like the motor is rich, but it's not because the scanner only sees the ECM's reaction to the O2 feedback, lean, and tries to add fuel. Anyway, if there are some primaries that don't work, the secondaries can't make up for it when they come on line. Hence the poor mid range and top end performance. The vibration thing is my tell tale as it's looking like a lean miss from where I sit. If I was there I'd do my smell test and use my scanner.

Next, I'm not all that happy with the fuel system's PSI readings, but with 21 year old pumps what do you expect. I would consider doing r&r on the pumps & socks later. The readings are on the low side of the FSM range. Oh, if you don't have one yet, please do look to buy a FSM at Heliminc.com....the best tool you can have in the box!

:cheers:
Tom

Hi Tom, I had a chance to run out to the garage and do some of the tests you specified. The plugs are definitely not cracked. I installed new ones yesterday. I did smell the exhaust and definitely burned my eyes coming out of the right side. Also, the first thing I bought for my Z was the FSMJ. I?m still learning to navigate through it. I?m very handy, but is not a mechanic of any sort. The FSM has definitely been very helpful in troubleshooting, and it?s a very interesting read in general that helps me understand the inner workings of this car.
I also performed the old trick of placing the tip of a long flathead screw driver on top of the injector connector and placing your ear on the tip of the screw driver handle to listen to the injector ticking away and confirming normal operation. Sure enough Injector #6 was not ticking at all, while all the rest ticked away like clockwork. So I pulled the #6 spark plug, and sure enough it was brand new when compared to plug #4 next to it which looked normal.
I also hooked the fuel pressure gauge up again, and noticed when I turned the key on, the fuel pumps kick in and the pressure goes up to about 53PSI for about 2 seconds while the pumps are on (which is within the normal 48-55psi range per FSM), but then immediately starts to slowly drop to zero within 5 seconds and stays there. Per FSM, when key is on, the fuel pumps charge the system to 48-55psi within the first two seconds, and the pressure should stay steady within that range after the pumps shut off and while the key is on. My only conclusion is that #6 injector is stuck open and is allowing the pressure to escape. Please correct me if I?m wrong. Would this also be the cause of the fuel pressure reading slightly lower than normal at 43psi while idling? Maybe the fuel pressure regulator is unable to keep up with that faulty injector? I?m just speculating at this point.
I was able to see part # on the primary Injector # 2, and it read 5235357. I googled this part # and it?s coming up as a GM OE injector manufactured by Rochester which I believe are the original Multec injectors.
Tom, I think new injectors are in order, but before I do that, I wanted to see if there is anything else I should check. I?m just still worried if my checking the injector resistance the other day caused the failure, or if it was a plain coincidence. Let me know what you think.

[mike100]

101% of these pre-93 GM injectors are bad so I wouldn't spend too much more time except to figure out how much money they are going to cost you.

Just in case you haven't found this- I think these will be the cheapest NEW injector set for the LT5.Click Me (http://www.fuelinjectorconnection.com/shop/index.php?_a=viewProd&productId=164)

I think there is a rebuilt option for $350 as well. The car is going to run so much smoother afterwords, trust me.

One other fundamental diagnostic that might give you piece of mind would be to disable the igntion/fuel inj by removing a fuse and run a compression test. Should be 200 psi or so after 3 cranks.

[mike100]

The only other bit that came to mind is that the car will run really badly for a few seconds after the new injectors go in. It will be injecting air until the fuel rails flow through the injecotrs and the dual mass flywheel will REALLY make some noise for 4-5 seconds- don't be alarmed- just expect it to be rough during the high idle flare up when the car starts.

[tomtom72]

Your Z and mine must be related as my right bank injectors went out also! It those damn right wing guys that cause all the trouble!! :p

Yea Gary it's the injectors so that's that! The fuel pressure is another issue.

I had much the same reading on my OEM pumps at about 16 yrs old or so. I think that they get tired is all. I bought new pumps and put them in and viola back up to factory specs. You don't have to do that right away. I waited at least two yrs before I replaced them and the only ill effects was I was missing some acceleration quickness old vs new pumps. Fuel delivery is key because we move so much air when the secondaries kick in! It was a nice dividend.;)

Oh, #6 injector is not causing the drop in FP, rather it proly is a couple of leakers somewhere. Proly from the secondary injectors as they are prone to get gummed up and leak a tiny bit. All you need is a few to loose FP rapidly upon shut down. It also could be the pump impellers as they wear from cavitation they don't fit tightly any longer and you leak back into the tank thru the feed line. The regulator is A-Okay as long as the hose doesn't have fuel in it.

Good deal, now go get you some new injectors and have some fun learning the first course...Plenum Pulling 101! :thumbsup:

[| 1990 ZR-1 |]

Mike and Tom,

Thanks for your help guys. I'm going to order the injectors and gaskets, and hopefully be done with these issues by this weekend. (Wishfull thinking). I'll post up the results.

[mike100]

Mike and Tom,

Thanks for your help guys. I'm going to order the injectors and gaskets, and hopefully be done with these issues by this weekend. (Wishfull thinking). I'll post up the results.

Then don't do what I did and decide to port the injector housings while you were in there or you'll really get behind schedule:p. You could have it done in a day taking your time to see how it comes apart.

[tomtom72]

Mike and Tom,

Thanks for your help guys. I'm going to order the injectors and gaskets, and hopefully be done with these issues by this weekend. (Wishfull thinking). I'll post up the results.

:mrgreen::thumbsup:

That's what this Bortherhood is all about. We try to help each other keep our cars in good order!

If you have any issues as you do your work don't forget to post up. Believe it or not this is a right of passage when you own an early, pre-92, ZR-1. Take your time and be patient as there is a lot of busy work under the plenum. Also, this bears repeating, check to see the bolts on the CCVBox Cover are tight as they create quite the oil mess. Check the T/Q on the I/H bolts and pull the starter to make certain the drain is clear & flowing. A camera could be useful for the wiring & vacuum line routing on the buttoning up phase....I didn't have a digital at the time I did mine and I had to take notes!

If you like I can PM you my cell number as a just in case situation. As I think I'm close but I believe there are some Z-Brothers closer.

:handshak:
Tom

[Mystic ZR-1]

Tom,
Is that part of the "vast right wing conspiracy" that Hillary spoke of? Their tentacles are everywhere...
Damn them!!! Sarah Palin, Glenn Beck, the Tea Baggers and Fox news too...
Doug
PS: What would Al Gore do?

[QB93Z]

Mike and Tom,

Thanks for your help guys. I'm going to order the injectors and gaskets, and hopefully be done with these issues by this weekend. (Wishfull thinking). I'll post up the results.

In addition to Tom's offer, if you want some help or advice, please contact me or any of the other WAZOO guys. I am only three hours away and would be glad to help out.

Jim
443-244-1247

[| 1990 ZR-1 |]

:mrgreen::thumbsup:

That's what this Bortherhood is all about. We try to help each other keep our cars in good order!

If you have any issues as you do your work don't forget to post up. Believe it or not this is a right of passage when you own an early, pre-92, ZR-1. Take your time and be patient as there is a lot of busy work under the plenum. Also, this bears repeating, check to see the bolts on the CCVBox Cover are tight as they create quite the oil mess. Check the T/Q on the I/H bolts and pull the starter to make certain the drain is clear & flowing. A camera could be useful for the wiring & vacuum line routing on the buttoning up phase....I didn't have a digital at the time I did mine and I had to take notes!

If you like I can PM you my cell number as a just in case situation. As I think I'm close but I believe there are some Z-Brothers closer.

:handshak:
Tom

Thanks Tom. I'll definitely take pics and will also take my time. I have a feeling those bolts are loose since I can see some oil under there. I will recheck everything and will give it a thorough cleaning. If you could PM me your cell, I'd greatly appreciate it. I ordered the FIC Lucas injectors and Jerry's seals and orings last night. I might start taking everything apart tonight.

[| 1990 ZR-1 |]

In addition to Tom's offer, if you want some help or advice, please contact me or any of the other WAZOO guys. I am only three hours away and would be glad to help out.

Jim
443-244-1247

Jim, thanks a bunch for the offer. I'm sure I'll have tons of quesitons for you and Tom.

[Z51JEFF]

The cam chains might be adding to the racket as well. I replaced the coils,plug wires when I did my injectors at 9000 miles.One of the new G.M. coils died with less than 5000 miles so I went with a set of MSDs and I put my LT5 wires back on the car.If your Vac system is holding vac for that long its in perfect shape.Typically these cycle a few seconds after about a minute give or take,thats what Ive seen anyway.As is already been stated any questions you might have can be answered right here.A little scary at first,take plenty of pictures...............and dig.Dont be surprised if it has to come off more than once.4 days after I got the car back together the Alt died.Plenum pull #2.http://i10.photobucket.com/albums/a136/FLYTYM/IMG_0023-2.jpg

[tomtom72]

Gary, you have a PM! ;)

Doug, Al Gore would drive a Prius.....after he gives up his Suburban 1500 w/454......with the up armored package.:blahblah:

That's the only problem with these high gas prices, the only cars on the road will be those stupid electric things and they even get in the way of my Cobalt! Oh yea my Cobalt is me being environmentally sensitive. It has the "B" motor so it too uses 93 octane.:p

[| 1990 ZR-1 |]

The cam chains might be adding to the racket as well. I replaced the coils,plug wires when I did my injectors at 9000 miles.One of the new G.M. coils died with less than 5000 miles so I went with a set of MSDs and I put my LT5 wires back on the car.If your Vac system is holding vac for that long its in perfect shape.Typically these cycle a few seconds after about a minute give or take,thats what Ive seen anyway.As is already been stated any questions you might have can be answered right here.A little scary at first,take plenty of pictures...............and dig.Dont be surprised if it has to come off more than once.4 days after I got the car back together the Alt died.Plenum pull #2.http://i10.photobucket.com/albums/a136/FLYTYM/IMG_0023-2.jpg
Thanks Jeff. I'll try to tackle as many preventative items as I can so I dont' have to pull it apart again. And if I have to pull the plenum ever again, it'll be a walk in the park, or at least that's what I'm hearing;)

[| 1990 ZR-1 |]

Gary, you have a PM! ;)

Doug, Al Gore would drive a Prius.....after he gives up his Suburban 1500 w/454......with the up armored package.:blahblah:

That's the only problem with these high gas prices, the only cars on the road will be those stupid electric things and they even get in the way of my Cobalt! Oh yea my Cobalt is me being environmentally sensitive. It has the "B" motor so it too uses 93 octane.:p
Thanks Tom. I just PM'ed you back. I'll give you a shout if I run into any trouble.
The FIC injectors will be here tomorrow, and if Jerry's gaskets get here before the weekend, I'm hoping ot be done by the end of this weekend.

[Z51JEFF]

Thanks Jeff. I'll try to tackle as many preventative items as I can so I dont' have to pull it apart again. And if I have to pull the plenum ever again, it'll be a walk in the park, or at least that's what I'm hearing;)

I didnt see anybody comment about coolant.You might need to drain about a half gallon.It would be interesting to see what everybody thinks is the biggest pain in the *** about doing this job.Ive done it 6 times and the one part I dread the most is getting the spark unit plugged in.You can check the secondaries with the plenum off.You need to hook up the fuel rails,make sure it is completely tight,no leaks.There is a pink wire at the second plug at the ECM I think.With the key on,ground this wire and the secondaries will open.If you want to check this out let me know and Ill check out a DVD I have that has the info on the system checks.One other item thats important,clean out the drain hole at the rear of the valley.This is to keep from flooding the starter.Its a small hole maybe about the size of a 1/4-20 bolt.Its been awhile so not sure on the size.

[| 1990 ZR-1 |]

I didnt see anybody comment about coolant.You might need to drain about a half gallon.It would be interesting to see what everybody thinks is the biggest pain in the *** about doing this job.Ive done it 6 times and the one part I dread the most is getting the spark unit plugged in.You can check the secondaries with the plenum off.You need to hook up the fuel rails,make sure it is completely tight,no leaks.There is a pink wire at the second plug at the ECM I think.With the key on,ground this wire and the secondaries will open.If you want to check this out let me know and Ill check out a DVD I have that has the info on the system checks.One other item thats important,clean out the drain hole at the rear of the valley.This is to keep from flooding the starter.Its a small hole maybe about the size of a 1/4-20 bolt.Its been awhile so not sure on the size.

Thanks Jeff. I read about draining the coolant. I also already checked the secondary falvew with the plenum on. They seem to work fine.

Should I replace the drive belt? I'm assuming it's a litte easier to do so with the plenum off.

[A26B]

The FIC injectors will be here tomorrow, and if Jerry's gaskets get here before the weekend, I'm hoping ot be done by the end of this weekend.

Your gasket/seal order should be delivered to you tomorrow as well.

[| 1990 ZR-1 |]

Your gasket/seal order should be delivered to you tomorrow as well.

Great news Jerry! Thanks for the confirmation.

[ittlfly]

I didnt see anybody comment about coolant.You might need to drain about a half gallon.It would be interesting to see what everybody thinks is the biggest pain in the *** about doing this job.Ive done it 6 times and the one part I dread the most is getting the spark unit plugged in.You can check the secondaries with the plenum off.You need to hook up the fuel rails,make sure it is completely tight,no leaks.There is a pink wire at the second plug at the ECM I think.With the key on,ground this wire and the secondaries will open.If you want to check this out let me know and Ill check out a DVD I have that has the info on the system checks.One other item thats important,clean out the drain hole at the rear of the valley.This is to keep from flooding the starter.Its a small hole maybe about the size of a 1/4-20 bolt.Its been awhile so not sure on the size.

Jeff...didn't I see somewhere that someone had used a slightly larger drill bit to enlarge the drain hole slightly to make the draining easier?? Or was I just smoking my own shorts. ;)

[tomtom72]

Jeff...didn't I see somewhere that someone had used a slightly larger drill bit to enlarge the drain hole slightly to make the draining easier?? Or was I just smoking my own shorts. ;)

I think there is a mod that makes another hole near the original one, bigger of course, and at an angle so the effluent runs down behind the flywheel unless you fab up a drain pipe like the OEM pipe. I never did that trick when I did my clean up. I just don't know if it would matter.

Gary, re your serp belt Q. Do you see any cracking on the ribbed side, on the smooth side? Is it chaffed at the edges? Do you know how old it is? I changed my OEM/BG one when I got my car in the winter of 04-05. It looked fine but it was 14.5 yrs old & had 7400 miles on it. I'm changing out the replacement shortly because it has gone 38k miles and it's 6 yrs old....jez I've had my car that long! Time flies when you're having fun I guess!....they are expensive. If it breaks I kind of doubt that the old nylon trick will work to get you home. JMHO.:o

:cheers:
Tom

[Z51JEFF]

Thanks Jeff. I read about draining the coolant. I also already checked the secondary falvew with the plenum on. They seem to work fine.

Should I replace the drive belt? I'm assuming it's a litte easier to do so with the plenum off.

The belt is an easy job with the plenum on,providing you get the right belt.Theres one belt,might be a Gates not sure that would not go on the car regardless of what I tried.The Goodyear belt went on the car no problem.As far as the drain hole,Ive read about people opening it up abit,I just cleaned it out and ran some water in the valley to make sure it was completely clear.

[| 1990 ZR-1 |]

I think there is a mod that makes another hole near the original one, bigger of course, and at an angle so the effluent runs down behind the flywheel unless you fab up a drain pipe like the OEM pipe. I never did that trick when I did my clean up. I just don't know if it would matter.

Gary, re your serp belt Q. Do you see any cracking on the ribbed side, on the smooth side? Is it chaffed at the edges? Do you know how old it is? I changed my OEM/BG one when I got my car in the winter of 04-05. It looked fine but it was 14.5 yrs old & had 7400 miles on it. I'm changing out the replacement shortly because it has gone 38k miles and it's 6 yrs old....jez I've had my car that long! Time flies when you're having fun I guess!....they are expensive. If it breaks I kind of doubt that the old nylon trick will work to get you home. JMHO.:o

:cheers:
Tom

Tom, the belt definitely looks old and is cracked, so I'll pick one up from Autozone and will swap it out.

BTW. I took the plenum off last night in less than 30 minutes!!:dancing I think I was so nervous that I overprepared and just carefully followed the FSM steps. My garage looked like a surgery room with all the right tools layed out strategically. It's a mess under there, so I have a alot of cleaning up to do tonight, and I'm hoping to finish everything up tomorrow since I'm off.

Quick queston regardinh the "drain hole" you guys keep referring to. Where exactly is it located?

[ittlfly]

Tom, the belt definitely looks old and is cracked, so I'll pick one up from Autozone and will swap it out.

BTW. I took the plenum off last night in less than 30 minutes!!:dancing I think I was so nervous that I overprepared and just carefully followed the FSM steps. My garage looked like a surgery room with all the right tools layed out strategically. It's a mess under there, so I have a alot of cleaning up to do tonight, and I'm hoping to finish everything up tomorrow since I'm off.

Quick queston regardinh the "drain hole" you guys keep referring to. Where exactly is it located?

It's under the starter.

[tomtom72]

Tom, the belt definitely looks old and is cracked, so I'll pick one up from Autozone and will swap it out.

BTW. I took the plenum off last night in less than 30 minutes!!:dancing I think I was so nervous that I overprepared and just carefully followed the FSM steps. My garage looked like a surgery room with all the right tools layed out strategically. It's a mess under there, so I have a alot of cleaning up to do tonight, and I'm hoping to finish everything up tomorrow since I'm off.

Quick queston regardinh the "drain hole" you guys keep referring to. Where exactly is it located?

:worship: :cheers: Good job! The drain hole is exactly where ittlfly said.

[| 1990 ZR-1 |]

Gentlemen, the beast is back!!

I finally finished everything up over this weekend, and what a difference! I believe my secondary injectors were pretty gummed up and were not operating properly. Now I definitely feel a difference between Normal and Full Power modes. I took her for a test drive the roads were slightly damp, and at 50 mph in 3rd gear the rear tires broke loose!! The power is definitely back, and the engine sounds strong and healty. It revs up very quickly, feels very responssive and light on it's feet. Now I just need to detail her and get her ready for the May 14th car show in Medford.

Special thanks to Tom for all his help and for being patient with me.;) Also thanks to everyone else who contributed to this thread.

Here's what I've done this weekend.

1. Replaced Primary and Secondary injectors with FIC Lucas Disc type injectors (very impressed with their packaging btw, primary and second injectors were in their own protective boxes clearly marked "Primary" and "Secondary", and each box contained a hand written flow chart. All injector O rings were included.

2. Removed the coil packs and the starter, and cleaned out the valley from debris and oil. The coils, the starter, and the stock wires are in great condition and look brand new once cleaned, therefore I chose not replace them at this time.

3. Blew through the drain hole with compressor (no debris there). I did not want to drill a secondary drain hole since I don't want any water or oil to leak on to the bell housing. IMO the stock drain hole is big enough in case a little bit of water gets in there, and I like how there is a drain tube connected to it that drains everything out from under the transmission housing.

4. Tightened the IH bolts to 20 lbs. They were very loose.

5. Zip tied all secondary vacuum connections for better seal. The vacuum was holding up well prior to this, but now it holds even longer.

5. Assembled the plenum and fuel lines with Jerry's Gasket and O ring set (great fit and fast shipping)

6. Replaced the spark plugs with AC Delco Part # 41-602 from AutoZone. Set the gap to .035

7. Replaced the drive belt with Dayco Belt Part # 5060805 from AutoZone

8. Replaced the Fuel Filter with Part # FF3504 from AutoZone

9. Changed the oil and oil filter with Amsoil AMO 10w40 Synthetic (2.5 gallons), and Bosch filter part # 3401

10. Ordered new Tires to be able to put the power down onto the pavement!! Nitto NT05 Summer Maximum Performance. Stock front and rear measurements. Will be delivered this Tuesday.

Quick note:
After everything was assembled and when I started the car, it still idled roughly. I was basically having the same symptoms as before. It was #6 injector again. It wasn?t "ticking" at which point I could only assume that there was no power getting to it. I traced my steps back to when I was measuring the injector resistance and thought that maybe I bent the ECM connector A8 (#6 cyl) with the pin I used, and now there was no contact. Sure enough that?s exactly what the issue was. So technically all my original primary injectors were fine including #6. It would have been a weird coincidence if #6 injector died right after I measured the resistance. So a word of caution, do not stick a large pin into the ECM connector when measuring the injector resistance. Otherwise you?re taking a chance of loosening the connections.

[Z51JEFF]

[QUOTE=| 1990 ZR-1 |So a word of caution, do not stick a large pin into the ECM connector when measuring the injector resistance. Otherwise you?re taking a chance of loosening the connections.[/QUOTE]

One of the veteran members here did this and took awhile to find the problem.As far as the tires breaking loose at 35 MPH,thats some scary $hit aint it!375 HP doesnt sound like alot in todays HP but its enough to put you into a tree in nothing flat.Its not hard to undersatnd why today people are still wading these cars up.When I first got my car years ago it had the the original tires that were as hard as hockey pucks.I think I got the tires to break loose going 50 one time.It was fun at first but got old real fast.Good to hear the cars back together.:thumbsup:

[mike100]

When I got my 91 last January, it still had 14 year old GSC's on the back and the inside was corded. found out the ABS still worked fine, and yes, it blew the tires as soon as the engine reached 4000 rpm pretty much everytime.

[tomtom72]

:saluting: to you Gary for a job well dunn!


See, these cars are very entertaining!:mrgreen:

[| 1990 ZR-1 |]

:saluting: to you Gary for a job well dunn!


See, these cars are very entertaining!:mrgreen:

Thanks Tom. That was me calling on Friday for a brief moment before I lost signal. I couldn't get her started, and after double checking everything, couldn't figure out what the issue was. I traced my steps back and realized that forgot to connect the two connectors on the underside of the plenum. No matter what I tried to get them plugged in without removing the plenum, didn't work. So I had to remove the plenum again. It only took 15 minutes though.

I do have another question for you. My car idles around 900-1100 rpm, and idles even higher when coasting to a stop in neutral. Through some research I noticed that Mark Haibeck sells a tune that should cure all those symptoms along with some other improvements. I also found a post by you stating that you have that tune. Are you still happy with it? Anything I should watch out for?

[tomtom72]

Hi Gary,

Jez I'm sorry that the signal went belly up! Yes I have that tune and thus far it is the best money that I have spent on any performance part for my car.....actually it's the only performance part my car has!

Everything that you are describing is typical of the 1990 EPROM with the AUAH programing which GM replaced with the AYBK program in a TSB as an answer to the complaints from owners. It was a big improvement over the AUAH EPROM.

I should say that I'm even more satisfied as I bought an AYBK EPROM from GM when they were still in stock and it corrected the idling issues and the coast down issues, but Marc's tweeks to the AUAH programing include eariler fan "on" temps to yield an operating temp closer to 200*F vs the GM 220*F programing. Marc also cleans up the fuel map so it is more effective at part & cruise throttle settings. Overall it's the best money I've spent on the car besides tires & gas! I highly advise any 90 owner to get Marc's chip!:worship:

:cheers:
Tom