Miss that is developing? (Help)

[TFENT]

Miss that is developing?

Ok so I had the Z in the garage for the last several months and I went to drive it last week and right out of the box the car would not start, cranked over but no start. Car is a 1990 w/ 32K all stock as far as I can tell. I let it sit for 20 minutes and went to start it and it cranked right up. But started to misfire.

I then drove it up to the gas station and dumped a van of Seafoam in it and 13 gallons of gas. It was running pretty rough then would smooth right out. Tried to drive it a bit then after 20 miles it stalled out at a light and cranked over but refused to start. Embarrassed I kept at it till it started and spit and sputtered. Died again. Then waited 30 more seconds and it started right up but with a heavy miss. Drove it 20 miles via freeway and no issues. In city driving at lights it is kicking and screaming, under part throttle even worst. Under heavy throttle runs pretty well. Popped a code 44 and 55. Now it is refusing to run hard under WOT so the problem whatever it is, is getting worst. Code 44 is Left O2 Sensor Lean, Code 55 is System Voltage.

I spoke to Jerry (Jerry?s Gaskets) and order O-Rings and gaskets in case I have to yank the Intake.

Its weird, the stalling makes me believe it could be a fuel pump because right after I start it, it runs pretty good. But the driving around and at an idle makes me think Fuel Injectors.

What are your thoughts??

Thanks in advance.

[rhipsher]

If they are the original injectors then its time to replace them. Its a well known fact the the ethinol in todays gas will eat them up and cause them to fail.

[XfireZ51]

Check fuel pressure. Start with filter then move towards back of car with fuel
pumps.

[TFENT]

Check fuel pressure. Start with filter then move towards back of car with fuel
pumps.

Ahhh, never changed the fuel filter...

[tomtom72]

Fuel filter & PSI test on the pumps like Dominic says.

The original owner of my car never changed the F/Filter, okay so he only did 7400 miles, but over 14 yrs. I r&r'ed it and the gas was orange that came out. I do it every yr now...maybe a bit of overkill:o

Remember that upon cold start both pumps run. Secondary pump shuts off after 140*(?) water temp is reached. On a warm/hot restart I think the secondary pump runs for a programed time limit, but I'm not 100% sure on that fact. KOEO pump test could be useful.

I know I swapped out my original pumps just this year just because they were 20 yrs old and I know they were testing at the lower end of the FSM acceptable PSI limits during the KOEO test.

When she acts up have you given a sniff to the exhaust? Does it smell rich or lean? I know the code says lean, but can you smell it? Did it make your eyes burn?

The time period description you give makes me want to say something electrical....you know as it heat soaks the issue gets worse. Generally that's what your symptoms seem to be saying. JMHO. Run down the pumps & filter, next I would look at checking for battery & alternator condition and then the ignition system condition, then the injector coils electrical condition.

Keep us in the loop and good luck!

:cheers:
Tom

[Mystic ZR-1]

Mine had all the same symptoms. 99.9% chance it's the fuel injectors. I had 5 of 16 out of spec. They're pretty reasonable $ @ fuelinjectorconnection.com or 770-888-1662 ask for John Banner. And get your gaskets from Jerry@ jerrysgaskets.com
Mystic ZR-1

[TFENT]

When she acts up have you given a sniff to the exhaust? Does it smell rich or lean? I know the code says lean, but can you smell it? Did it make your eyes burn?


:cheers:
Tom

Tom:

No smell what so ever, either way. Doesn't smell like raw gas nor does it make your eyes burn.

I am going to change the fuel filter then check fuel pressure to give me a base line. If I am good there then I will just order fuel injectors from FI Connection and get 4 replacement coils. Swap those out and then if that doesn't solve the problem then I will replace the pumps.

I really wish someone had photos of them checking the fuel injectors on the ECM using Marc's instructions. So I can see exactly how to do it without messing up the pins.

[A26B]

Tom,
A little more information.

1. Always begin diagnostics with the lowest numerical DTC first. In this case, DTC 44. When the lowest code is resolved, the higher code will be too. Removal of stored codes is accomplished by disconnecting the battery for about a minute and is recommended.

2. There are 2 components to injectors, electrical & mechanical. A corroded or plugged injector can test just fine for coil resistance and still be the problem, so don't rely only on the ECM probe procedure unless it indicates defective.

3. ALWAYS keep the fuel tank full during long periods of inactivity. The pump assy can/will rust, plugging the strainers, fouling/ruining the pumps & clogging the filter.
Here's a photo of the one from my Ruby Zee. When it gets this bad, cleaning the tank is part of the fix.
http://i190.photobucket.com/albums/z224/A26B/FuelPumpAssy.jpg

4. For 90~92 models, injectors have been the predominate cause of misses without codes thrown, followed by bad ignition coils, then plug wires. Odds are, your's will be be fuel related considering the DTC 44.

Good luck with the repairs and keep us posted. Thanks for the advice during our telecon! I appreciate it:cheers:

[TFENT]

Thank you Jerry!

I thoroughly enjoyed the conversation we had Friday, you are a wealth of of valuable information. I look forward to getting your gaskets and proceeding with the intake removal.

[A26B]

Tom,

Here's a photo diagram (made by a member to share his experience) from an old post I found.
http://i158.photobucket.com/albums/t120/sdba11/CheckingZR1FuelInjectorResistances.gif
Should help some. Also, FWIW, another member enlarged the connectors while probing for resistance checks on the injectors, creating a different 7 very elusive problem...intermittent connections. So, be careful while probing. & don't stick the probe into the connector.

[XfireZ51]

This is actually easier than it looks once setup. ;)

[dallas]

Tom,
A little more information.

1. Always begin diagnostics with the lowest numerical DTC first. In this case, DTC 44. When the lowest code is resolved, the higher code will be too. Removal of stored codes is accomplished by disconnecting the battery for about a minute and is recommended.

2. There are 2 components to injectors, electrical & mechanical. A corroded or plugged injector can test just fine for coil resistance and still be the problem, so don't rely only on the ECM probe procedure unless it indicates defective.

3. ALWAYS keep the fuel tank full during long periods of inactivity. The pump assy can/will rust, plugging the strainers, fouling/ruining the pumps & clogging the filter.
Here's a photo of the one from my Ruby Zee. When it gets this bad, cleaning the tank is part of the fix.
http://i190.photobucket.com/albums/z224/A26B/FuelPumpAssy.jpg


That is really ugly! Years ago we used to put a little kerosene into the tank to keep rust down. Does that work with today's fuel systems?

[TFENT]

Well gentleman we opened up the intake today to install the new injectors?

Man what a mess it was under there. It was very frustrating to so and I thought I was going to scratch or break everything we touched.

Turns out only one primary and one secondary injectors were bad. Below 10 ohms. The rest are 13 and above. They didn?t want to come out of the holes either, it took plenty of patience to finally extract them all and even when the fuel rail was lifted there were several still stuck in the intake. I am just glad nothing broke. I disassembled the rails and changed the o-rings then started to replace each injector one at a time. Then the lower o-rings in the intake. Till all was done. It seamed to take forever and I was confused by the way the new injectors looked. The primary and secondary injectors I received from Fuel Injection Connection look identical in structure to the ones I was pulling out of the car. But after test fitting them they both went right in. except for the fact they didn?t look like they were seating in all the way into the Intake. The secondary?s sit up a bit in the housing. I checked and rechecked the fit and all of the o-rings were snug and below the surface so I figured they were seated. Then the task of reinstalling the plenum?

I discovered the PCV grommet was REALLY loose as well as the rubber piece at the front of the motor under the throttle body on the drivers side. Both of these are thick rubber that is old and tired. Both need to be replaced.

Some antifreeze got into the engine and we removed the plugs to expel it and went to start it up. Started right up and was rough for a few moments, compliments of the antifreeze I am sure. Then it settled right down to a nice smooth idle. Then we started to hear the vacuum leak? uggggg! It is only there when the engine is running and lasts a few moments after it is shut off. Bought a vacuum pump to test out all the connectors.

It is emanating from the rear of the intake on the passenger side. It is not allowing the secondary?s from actuating. Engine purrs like a kitten at an idle as stated but once you get on it its flat, hesitates, threw a ses light, and doesnt want to rev? gonna have to remove the plenum once again this week to see what we missed or broke.

I am hoping we can reuse the gaskets for the plenum again and have ordered both PCV valves. Now I need to source the rubber pieces? I will keep you posted and thanks for all the assistance here.

[Paul Workman]

TFENT, fuel pressure at idle doesn't always tell the story. Try putting an extension on your fuel pressure gauge and extending it to the windshield where you can tape it where you can see it and then go for a drive and a few WOT bursts.

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/FPtestLarge.jpg

At idle or slow speeds, the pressure will be around 45 pounds, give or take 2-3#, depending on throttle.
At WOT the secondary pump kicks in an pressure should snap up and read a steady 50-52ish - all the way to 7000+rpm.

(Note: If your pressure gauge needle bounces a little at low speed, you may have some air in the gauge tube. Give the bleed button a couple of taps until air stops leaking out of the bleed tube - might wanna catch the fuel that might squirt out in a rag or something.)

You replaced the injectors already, but for those having similar problems, injectors that "ohm out" OK can still be gummed up or sticking. A slick trick suggested to me by Marc H, is if you have the plenum removed anyway, is to check the injectors for flow and spray pattern.

I did the test with the injectors still in the car. I attached a piece of zip cord (lamp wire) to the battery using some test leads having alligator clips on each end. (The clips I bought in a pack at Radio Shack for a few bucks many moonz ago). I then clipped one wire to one of the pins of the injector under test (the electrical plug remove previously), and bumping the other alligator clip on the remaining connector pin, you can get a good idea of how the injector is running.

With the ignition key in the ON position to pressurize the fuel rails, you listen for a clean "click-click" when the injector opens and closes. This signals the "guts" are free of gum or foreign debris; only one "click" or none indicates some kind of problem. And, while listening for the "clicks", you can observe the spray pattern from the injectors. All spray patterns should be uniform when injectors are energized, and when electrical current is removed, there should be NO fuel leaking out.

A leak-down test not only tests the injectors, but the check valves in the fuel pumps as well. A failed leak-down test** is not proof of an injector leaking. For that, a simple test conducted at the fill door will distinguish injectors from fuel pump check valves.

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/7-25-09003.jpg

I set my compressor regulator to 50#, but a hand pump and your fuel pressure gauge will work just as well, and connected it to the fuel pump outlet line and pressurized the fuel line with a short burst. If the fuel pressure gauge shows steady pressure, and no air is leaking at your nozzle connection, then the injectors are not leaking. (course, with the plenum off, you can see which one is leaking, if one is!)

The check valves in the pumps can be checked the same way. Pressurize the outlet pipe and check for air leaking somewhere. And, BTW, if you replace your pumps, I would not try to reuse those funky plastic hose clamps that came from the factory. I put a "worm gear" hose clamp on the rubber lines (and Marc Haibeck recommends the same).

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/7-25-09008.jpg

(In my fuel pressure fiasco, not only was my secondary pump bad, but the replacement - new out of the box - had a bad check valve. I should have suspected something was up when I realized the box had been opened before I bought the pump...I scrawled "BAD" on the body of the pump with a black marker and returned it in the box to exchange it for another.)

As for the vacuum leak near the rear of the plenum, before pulling the plenum just yet, I'd want to check the easy stuff in that area first:

Inspect the vacuum plumbing between the MAP sensor and the plenum. Fussing with it in the process of removing it to get the plenum off often results in a weak or crack in the plastic tubing (or the like). another thing is to cinch up a tie-wrap around the 90* rubber elbow, against the Map sensor as a guard against backfire or old rubber loosing its elasticity. The other vacuum connection is the fuel pressure regulator, but it is easy to get to and fix. Course, don't forget the power brake booster hose...which I have done more than once...;)

Not to beat a dead horse, but NO secondaries = NO secondary vacuum leaks, or any other problems w/ secondaries... Just a thought.

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/ZR-1008.jpg
http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/ZR-1009.jpg

I know, I know...blah, blah, blah...

Paul.

[TFENT]

Paul:

Thank you for the assist! Checking out all the things you mentioned.

Pulled codes 22 and 34 out of the computer today. Need to address those asap. Then test other areas as mentioned by Paul. I am thinking the MAP one maybe the vacuum leak i am hearing and the reasons the secondaries are NOT kicking in. The TPS one was adjusted after the installation of the plenum was completed and was at .54 volts according to the scan tool we used.

I am also in search of some other rubber parts in another thread. The PCV one at the rear of the motor and the one that attaches the PCV metal line to the area behind the throttle body at the front of the motor. The Samco part is like $170. What a rip off!

[TFENT]

Another update to the saga?

Ok well today we put new Bosch fuel pumps in. Took it for a spin and got a ton of codes out of it. 31, 33, 42, 46, and 55.

Put a fuel pressure gauge on it and it reads 50psi and then starts to drop slowly but within 5 mins dropped to 45psi. In addition I heard the vacuum pump going off every 5-10 secs. I think I know why. I checked all the vacuum lines under the plenum and they all held but one check valve that goes up to the drives side of the intake between the cylinders. I popped that line and put my thumb over it and the pump stopped. Where on earth do I get this little check valve from??

The car runs worst now then before and it died at an intersection during the test drive and it didn?t want to start for about 2 mins then fired up. It?s missing badly now. The only thing I haven?t replaced is the coils?

[rhipsher]

Paul! Your my kinda people. Being long winded is not a bad thing. Just means your more detailed.

[tomtom72]

Tom,

31 Cam sensor used to happen to me a lot. I took apart the connector and cleaned it and dried it and lubricated the gasket and pins with dielectric and have not had an issue since. One thing about that DTC is it cancels the secondaries when it sets. One other thing, and it may not be related to me stopping my 31 from setting is that I slowly move the ignition key from off thru to on, wait for all the lights on the DIC to display & go off and then go to start. I have no clue if that played any part in my solution to my car's 31.

33 low vacuum/high MAP voltage reading by ECM. The good part is that the ECM is okay. The MAP hose maybe off, or the MAP maybe dunn.

42 EST. I had this one and did all the electronic diagnostics in the flow chart onlt to find that I had bent one pin on the DIS box, therefore DTC 42 set. I put the connector back on upside down at first, bent the pin, righted the connector, installed same but the pin was bent and I missed it!:o My Bad!

46 VATS. pill on key dirty? I'm not too swift with the VATS system, try to talk with tccrabs ( tom from CA ).

55 basically the fuel is going lean at 2* tip in. If I read the FSM correctly. 2* pump not coming on? Try driving in "normal" power setting with the key and compare that to key on. Or, you can do the entire KOEO fuel pump diagnostic flow chart. That test will tell you if both pumps are working, but doing that test on a stone cold motor is the best chance for useful diagnostic results on both pumps. I say that because on a cold motor the secondary pump runs longer so it's part of the test gives more valid data, JMHO.:o On a hot motor the 2* pump only runs for 2 seconds at start up. You also can use the relay and probe C terminal. The test light will light up for 2 seconds and then go out. Or you can use the flow chart under DTC55.

Sorry to be so long winded. Start with the lowest DTC # and work thru the DTC's 31, 33 and 42 with visual / cleaning checks first. I would try to clear them first if this was me working on my car. After I was satisfied that I did proper mechanical work, I'd clear the DTC's and try another start up and see what presented. I would expect that the higher # DTC's would represent, and then I'd work them from low # to highest #. Again JMHO.

:cheers:
Tom

[TFENT]

I spoke to Marc H this morning about these issues I am having.

Here is what he told me. FP should be at 48psi or better cold on key on only. 43psi while idling and 50+ while under WOT. If I don?t have that then a code 55 will pop.

The other codes could all be related to a pinched TPS sensor wire at the plenum. Stated this occurs frequently after a plenum pull. Check the wires to make sure this hasn?t happened to me. Since this wasn?t a problem before the 1st plenum pull.

The check valve I have leaking in the vacuum is a simple part made by Standard Motor #DCV1

He doesn?t think I have a bad plug, wires, or coil since it is running lean.

Next course of action is plenum pull #3:

Change out plugs, coils, check valve. Inspect the DIS for bent pins, check TPS wires for pinched wires, check routing of the plug wires to make sure they are isolated from DIS wires. Ohm and inspect all the new injectors. And lastly check FP again, but this time while driving.

Did I miss anything?

[dallas]

I had trouble with check valves so I added an extra on each side. I now have ones at the middle of the plenum where I can access them from the outside if needed. I haven't had any problems since, and I think I may have purchased the backups at either AZ or the dealer.

http://images35.fotki.com/v1163/photos/1/1050392/4402413/018-vi.jpg (http://public.fotki.com/dallas916/zr-1/018.html)Hosted on Fotki (http://www.fotki.com)

You should be able to expand this pic to see the check valve clearly in the center of the plenum right below the throttle lines.

[TFENT]

Newest update 9-10-10

OK so tonight I checked the Fuel Pressure of both the new primary and secondary pumps. Both are pushing 50+ without the engine running.

That?s the good news. Bad news is the car will only start after its been sitting for an extended period of time. After 15-20 mins of checking the fuel pumps it will not start. So I took the opportunity to check the spark at each cylinder. Some were VERY blue several are orange and one was yellow. I know this is enough to warrant new coils, which I have ready to install, but it does not make any sense that the car refuses to even want to start. And when it does run its very poorly and throws a lean code.

This leads me to believe that there is something preventing the fuel injectors from firing. These are brand new injectors from FIC. I was told this is a new line of injectors available from only them and here is the link for them. http://fuelinjectorconnection.com/shop/index.php?_a=viewProd&productId=208 even Marc H hasn?t heard about these yet.

Now I don?t know how to go about checking to see if these are actually working or not. I am going to pull the plenum once again tomorrow and at minimum change out the coils but besides checking the ohms on each injector how do I test to see if they are actually firing??? I am thinking these are my problem?

Thoughts??

[TFENT]

Changed the coils today. MUCH better BUT still have an occasional miss AND it sometimes throws a code 55 lean. So I hooked up the fuel pressure gauge and ran it for a few 120mph+ WOT runs and the pressure is 55-60psi at WOT. On one occasion I downshifted to pass someone and it bogged out and threw the 55. Then ran terrible till I got back to the shop and started to miss-fire for a few mins. Then cycled the key checked the code and went for another run. Ran perfect till I let it sit and idle. It misses still....

I am thinking I have a bad injector or two...

Thoughts?

[Paul Workman]

Changed the coils today. MUCH better BUT still have an occasional miss AND it sometimes throws a code 55 lean. So I hooked up the fuel pressure gauge and ran it for a few 120mph+ WOT runs and the pressure is 55-60psi at WOT. On one occasion I downshifted to pass someone and it bogged out and threw the 55. Then ran terrible till I got back to the shop and started to miss-fire for a few mins. Then cycled the key checked the code and went for another run. Ran perfect till I let it sit and idle. It misses still....

I am thinking I have a bad injector or two...

Thoughts?

For one thing, the fuel pressure escursion to 60 psi = not what the book says it should be! Kinda sounds like a pressure regulator is out to lunch, which would account for a plethera of bogging, and lean and loading up (resulting in a miss at idle). Make sure the vacuum hose is connected properly to the FP regulator. If in fact it is, then that regulator needs to be changed. According to the FSM, 50-52 ish is the ceiling, and it should remain steady at WOT - the ECM is counting on that (especially in WOT/open loop condition!).

If in fact the FP reg is at the root of the evil, I would expect to see some pretty sooty plugs too. It might be worth pulling them and seeing what is going on.

In any case...one problem at a time, the FP thing is important, methinks!

P.

[XfireZ51]

Check to see if there's gas in regulator. Could be damaged diaphragm

[TFENT]

Well Paul. It's all over the place while driving it but when you step on it the needle bounces like you hooked it up to a vibrator. from high 40's to the 60 mark. NOT steady at all.

The Vacuum line is hooked up and in perfect shape. i triple checked. it.

Plugs are very sooty and the sometimes the car starts and sometimes it doesn't. Sometime when its cold some time when it's not cold. Just as it will sit there and idle for 5 mins perfectly then it will miss and just stall. Sometimes it will idle for a half-hour and be fine one min and then just start missing all over the board. Tried seeing what cylinders it happening to in case it was a bad injector or two but seems that when we are trying to track it that cylinder you are at is the dead one. on all but just a few and those ate 7 and 8. Closest to the regulator and fuel supply... hmmmmm:confused:

[TFENT]

I haven't touched the car in a few days and now it won't start at all. Cranks but no start...

Does anyone have an ECM i can borrow???

[tomtom72]

I have a spare ECM for my 90. Yours is a 91?, sorry i don't remember. Anyway, I have a spare ECM and an OEM 90 1st design chip, AUAH configuration. Let me know and in the mean time I'll go dig out my spare ECM. It may be that my spare is good up to a 92, I have to run down the p/n to be sure on that issue but I know it is good for a 90.

Secondly. and no offense meant by this. It seems that you are dumping fuel if the plugs are sooty. The injectors could be sticking open? The hard restart symptom is one sign of leaking injectors.

Also, another issue is the bouncing F/Pressure readings. I swapped a new pump/sender unit into my car this yr and my readings were kind of like yours with the bouncing when running. I just had to flatbed her home and when I pulled the pump unit from the tank I found one of those black plastic clamps had a crack in it. It was the one at the "out" pipe. No fuel = no start.:o I wonder if the cracked plastic clamp was the reason for my bouncing F/P readings. Just a thought.

:cheers:
Tom

[XfireZ51]

Tom,
Lgaff had that same problem. Plastic clamp not holding allowing some of fuel to spurt back into tank. Replace with real hose clamps.

I have a spare ECM for my 90. Yours is a 91?, sorry i don't remember. Anyway, I have a spare ECM and an OEM 90 1st design chip, AUAH configuration. Let me know and in the mean time I'll go dig out my spare ECM. It may be that my spare is good up to a 92, I have to run down the p/n to be sure on that issue but I know it is good for a 90.

Secondly. and no offense meant by this. It seems that you are dumping fuel if the plugs are sooty. The injectors could be sticking open? The hard restart symptom is one sign of leaking injectors.

Also, another issue is the bouncing F/Pressure readings. I swapped a new pump/sender unit into my car this yr and my readings were kind of like yours with the bouncing when running. I just had to flatbed her home and when I pulled the pump unit from the tank I found one of those black plastic clamps had a crack in it. It was the one at the "out" pipe. No fuel = no start.:o I wonder if the cracked plastic clamp was the reason for my bouncing F/P readings. Just a thought.

:cheers:
Tom

[TFENT]

I have a spare ECM for my 90. Yours is a 91?, sorry i don't remember. Anyway, I have a spare ECM and an OEM 90 1st design chip, AUAH configuration. Let me know and in the mean time I'll go dig out my spare ECM. It may be that my spare is good up to a 92, I have to run down the p/n to be sure on that issue but I know it is good for a 90.

Secondly. and no offense meant by this. It seems that you are dumping fuel if the plugs are sooty. The injectors could be sticking open? The hard restart symptom is one sign of leaking injectors.

Also, another issue is the bouncing F/Pressure readings. I swapped a new pump/sender unit into my car this yr and my readings were kind of like yours with the bouncing when running. I just had to flatbed her home and when I pulled the pump unit from the tank I found one of those black plastic clamps had a crack in it. It was the one at the "out" pipe. No fuel = no start.:o I wonder if the cracked plastic clamp was the reason for my bouncing F/P readings. Just a thought.

:cheers:
Tom

Tom:

Thank you for the assist. It is a 1990

In addition we replaced both fuel pumps a few weeks ago trying to solve the miss/no start. All the clamps were replaced with metal worm gear clamps. The whole assembly was in very good condition and I had a brand new one standing by to go in if it wasn't.

Fuel Injector Connection just sent a whole new batch of Injectors. So I am hoping that I had several bad injectors and a bad Fuel Pressure reg. because this is really irritating me to no end. Plenum pull #5 coming soon.

[Paul Workman]

Well Paul. It's all over the place while driving it but when you step on it the needle bounces like you hooked it up to a vibrator. from high 40's to the 60 mark. NOT steady at all.

The Vacuum line is hooked up and in perfect shape. i triple checked. it.

Plugs are very sooty and the sometimes the car starts and sometimes it doesn't. Sometime when its cold some time when it's not cold. Just as it will sit there and idle for 5 mins perfectly then it will miss and just stall. Sometimes it will idle for a half-hour and be fine one min and then just start missing all over the board. Tried seeing what cylinders it happening to in case it was a bad injector or two but seems that when we are trying to track it that cylinder you are at is the dead one. on all but just a few and those ate 7 and 8. Closest to the regulator and fuel supply... hmmmmm:confused:

One crisis at a time, I recon!

First, that fuel pressure thing needs to be resolved. Sounds like a new regulator is in order.
Second, you might either clean and install or buy some standard (AC Delco) plugs and begin again with a fresh, clean set. Then we can go from there.

FWIW, with the fuel pressure all over the map, the fuel flow is too, and the ECM and O2s are not able to provide accurate fueling information - mostly rich, is my guess, which will foul the plugs to the point it may well be a subset of your starting probem.

Just my 2 cents.

P.

[TFENT]

One crisis at a time, I recon!

First, that fuel pressure thing needs to be resolved. Sounds like a new regulator is in order.
Second, you might either clean and install or buy some standard (AC Delco) plugs and begin again with a fresh, clean set. Then we can go from there.

FWIW, with the fuel pressure all over the map, the fuel flow is too, and the ECM and O2s are not able to provide accurate fueling information - mostly rich, is my guess, which will foul the plugs to the point it may well be a subset of your starting problem.

Just my 2 cents.

P.

Paul:

Your 2 cents is worth it my friend.

Just to clarify.

Plugs:
The plugs are brand new after the sooty ones were removed, maybe 10 miles on them.

FP Readings:
Normal at part throttle very steady, varies with load 38-55psi. Then vibrates excessively under WOT 48-60+ psi. Hard to tell how high/low it goes as u can barely see the needle its moving so fast.

No Start:
If you let the car sit all night and go to crank it it starts just fine no prob. If you turn it right off and try it again it's a 50/50 shot it will start back up. Again if you let it sit for hours it will start right back up no prob. FP readings are normal. 45-50psi and slowly leaks down to 30's after 10 mins or so.

[tomtom72]

Okay Tom. Your call as yours is a 90 also. I can ship you the ECM with the AUAH Prom installed or with out the PROM installed. Just say the word and I'll get to it.

:cheers:
Tom

Done deal! shipped via USPS Express Mail. Tom you have a PM with the tracking number!

[TFENT]

Update 9-20

Thanks to Tom I received a spare ECM to try in the car. For the last several days the car has refused to start, as stated before it had fuel pressure and spark. After it once again refused to start today we immediately swapped out the ECM and cranked her over. She started right up and at first back fire a bit then smoothed right out and never miss fired after letting it sit there for several minutes. Then once it was a little warmed up I juiced it a bit. Again it back fired at first and then was quick to react to the throttle response. VERY quick to respond to it actually. I believe the back firing is from all the gas in some cylinders that were not working properly and it being cleaned out. No i am not going to jump on a limb here and say it's cured for fear of jinxing myself. But initially it seam to be much smoother of an idle and it's running and responding "normal". The real test will be after a few days of seeing if she wants to start "on command" and then taking her out for a few WOT runs to see if we get any codes. If at that point she performs as designed I will know I had several issues and one being an ECM that didn't want to accurately work all the time.

I will keep you all posted.

BTW Tom sent me this ECM overnight express mail and wouldn't let me pay for it. Man what a BROTHER!!!

[tccrab]

Update 9-20

BTW Tom sent me this ECM overnight express mail and wouldn't let me pay for it. Man what a BROTHER!!!


The Brotherhood Of The Beast is ALIVE AND WELL!!!

TomTom72, U Da Man!!

TomC
'Crabs

[tomtom72]

Tom, I'm glad that there seems to be some sort of help with the ECM. I just question if it is the ECM or the EPROM. Sorry for sticking my two cents in on this issue.:o

How many cold solder joints could one of our ECM's have, or is it likely that our ECM's could have gizmos become intermittent on the main board?

Or, is it more likely that cold solder and bad/intermittent gizmos could happen to our EPROMS?

Humor me, just swap out EPROMS, take mine and put it in your ECM and let's see what transpires?

Just tossing this out there as a fwiw. Lord knows I'm not an electronics wiz-kid, word!:icon_scra

Oh, take your time with this trouble shooting. No need to waste any money on parts till you are satisfied with your diagnostics. Soooo, keep the ECM for as long as you feel is needed to run this issue down to ground!

:cheers:
Tom

[TFENT]

Tom:

I can't thank you enough... I can see the light at the end of the tunnel now and feel like we took a huge step in figuring this thing out.

I will definitely swap out the PROM's and try them out. Good suggestion.

But if I do need a new PCM/ECU where do I get one?? Suggestions?

[tomtom72]

Okay Tom, I found a place....I can't remember where I ran across him. I think it was over at the other ZR-1 section at the other corvette forum...I think.

Anyway I was going to send him my original ECM, it took a dump on me awhile back with a DTC61...grounding issue I think on that circuit?

Link: http://gmautocomputers.com/
I was going to call them first to see if I could get a sense of their confidence level in working a ZR-1's ECM. Their site says that they can fix them all.

The only other suggestion I can offer up is either corvette recycling, Les Stanford Chevrolet(?), or partszoneonline.com is where I got my spare ECM five yrs ago.

:cheers:
Tom