89gta22

So I've had several years of terrible performance out of my 89 TA GTA. Intermittent run then stall with a no start. Can't tell you how many times she left me stranded by the side of the road. Just this year I decided it was time to resolve all the issues and replaced the following:

- New (used) low miles engine and fan wiring harness. The old ones had seen better days.
- New Distributor
- New Plugs
- New plug Wires
- New sensors all around (I mean literally every one)
- New Injectors (all 8)

Only thing Not Changed - EGR valve

Car ran like a dream, better than she ever did, for about a week and then suddenly the other day the idle started to surge significantly, 1200RPM-400RPM-1500-500 etc and then within a few minutes dies. Car wound not start, sat for about 10 minutes then it started up. Drove home and the next morning when I went to take it out, car would crank but not a single sputter or attempt to turn over. No check engine light on or code readout.

I got myself the GM service manual for 1989 to try and solve the problem and here is what I've come down to after running through the diagnosis for a "no start with crank" situation:

1. Noid light test @ injectors (all 8) No pulse signal at crank or ignition on.

2. Confirmed TPS is set to .54v
3. Confirmed with Test light injectors @ ign. on are hot to both black and black/pnk or black/grn wires.
4. Confirmed 42 PSI at at fuel rails
5. Probed CKT 467 and 468 at ECM pigtail with test light, no light.
6. Disconnected all 8 injectors and ECM pigtail and probed blk/pnk, blk/grn, and blk wires at all 8 injectors. Solid Black wire test light ON, blk/pnk and blk/grn no light.

SO, after following the shop manual diagnostics and the above results, it would seem to me that the ECM is the culprit. However I am looking for validation from someone who has run through this diagnosis before. Would the ECM cause a no start or engine idle surge if it was bad? Just want to be sure before I go and get a new ECM. What about the Ignition module?

PS: This car has had 3 prior owners and it looks like the ECM is a remanufacture 7-7165. Who knows how long ago it was replaced though.

Thanks!

mjdavis68

iTrader: (1)

sounds just like my issue

89gta22

Since there seem to be so many people having the exact same issues as I am I'm going to update as I continue my search. Today I purchased a new ECM and swapped it in. Immediately my no start situation went away and the car cranked over. I assumed I had resolved the issue so I took the car out for a victory drive. Within 15 minutes I pulled up to a traffic light and as the car settled to idle it died. Cranked and cranked.....nothing. Let her sit for about 5 minutes then tried again and boom it started up.

So now that I know it was not necessarily the computer that was causing my stall/no start situation I'm thinking the following:
1. Bad prom. I read a few blogs from guys who replaced several computers only to find he prom was the issue. Since I swapped the old computer prom into the new computer I supposed it's possible but the manual says nothing about bad proms causing no start.
2. Replacing the egr. Stuck open egr possibly causing the issue, but I doubt it.
3. Thinking maybe a short in the Vats decoder Control Module. Since vats can send signal to ECM to stop pulsing injectors, I wonder if somehow when the car heats up the vats module connections or circuitry are failing causing an injector pulse cutout????? It would be an odd scenario but I suppose it's possible. Purchased a vats bypass module today as well from hawks third gen so we shall see if that solves it.

That's where I'm at now. Will update after the new parts are installed.

NCC-2569

iTrader: (1)

No code readout? Not even a code 12? That should be your ECM, then.

NCC-2569

iTrader: (1)

Ok, you were faster to post.
IIRC, the VATS module sends a reference pulse to the ECM for startup. Once it's running, the influence is over.
How has vehicle performance been? Did you feel some kind of power loss while driving?

89gta22

Thanks for the replies. Sorry for not being clear, yes the check engine ECM indication code 12 did show at the dash when I jumped the test terminals, but no check engine failure codes were thrown.

Engine performance has been great. Now that I've replaced so many parts I've seen a tremendous gain in power (injectors and new distributor had the biggest impact). Car runs great when it gets going but somewhere around 5-10 minutes of driving or or sitting in idle and I begin to see the idle surge and the the stall issue. Car idles typically around 600 rpm.

NCC-2569

iTrader: (1)

Ah ok. Can you hook up a computer or know someone who can do it for you? Would be interesting to see some values.
As you swapped your distributor, which components came with it (cap, rotor, ignition module, pickup coil, nothing)?
The pickup coil is temperature sensitive in certain cases.
Have you ever checked your ignition coil? The fat thing attached to the distributor cap's external center pin? That's quite easily done if you have a multimeter and won't cost you a thing.
There's a guide on how to check it correctly, something like this:
http://easyautodiagnostics.com/gm_ic...n_module_5.php
Or this:
http://www.google.de/imgres?imgurl=h...ed=0CGAQrQMwEQ

89gta22

I wish I knew someone who could do this for me but I'll ask around tomorrow after I've got the new parts in. If I can get this I will be sure to post it.

As for the distributor, it was a complete unit, cap, rotor and module included. I had that installed by my mechanic so I was sure the timing was set correctly too.

The aux ignition cool

89gta22

[QUOTE=89gta22;5774449]I wish I knew someone who could do this for me but I'll ask around tomorrow after I've got the new parts in. If I can get this I will be sure to post it.

As for the distributor, it was a complete unit, cap, rotor and module included. I had that installed by my mechanic so I was sure the timing was set correctly too.

The aux ignition coil is a good suggestion. I know these can become heat soaked and cause hot start issues. I replaced it about a year and a half ago with an msd model thinking that was the culprit but it can't hurt to put a new one in to rule that out either. I'll add that to my list for today. Thanks!

NCC-2569

iTrader: (1)

Your MSD coil should not be faulty after such short time, but you never know.

Thinking back to a time with another GM car... it once stalled at the traffic lights, took a moment to let me start it up again, just to die again around the next bend.
That was an EGR issue. I had it replaced and all was good again.
Does your service manual have a diagnostic tree for that? Should be somewhere in the drivability and emissions chapter.

Have you checked anything in the direction of fuel supply? Pump, pressure, FPR?
That pump also gets some temperature over time and the fuel pressure regulator can also cause the strangest issues if faulty.

89gta22

The manual does have diagnostic flow charts for just about every emissions control system so I'll have to double check if there is a comprehensive egr test. If I recall, the "crank no start" summary said that pulling the vacuum line should throw a code and if not the EGR should be replaced. Since I bought a new EGR I didn't try that. I never knew that the EGR could cause so many issues, hopefully that's all it is that's causing this headache.

Fuel supply seems to be good, I plugged a fuel pressure gauge into the Schroeder valve on the rails and got 40psi and I can hear the fuel pump priming for a few seconds when the car is in ignition on. I did not change the regulator, fuel pump or fuel pump relay though. Could the car have steady 40 psi at rails and then cutout during driving?

After I install the EGR I will update on the status. I suppose I could leave the fuel pressure gauge in while driving around the block so I can see what she does when the car comes to a stop. Thank so much for your help!

NCC-2569

iTrader: (1)

You're welcome. I just hope we're going in the right direction and you can solve the issues.
Would be interesting to have some of the electrics guys comment on your findings around the injectors, because I don't know exactly what SHOULD be happening there.

89gta22

I wanted to update everyone on the status of my 89 GTA. Since this has a been a progressive diagnosis I want to summarize the whole story so that anyone dealing with these same issues can follow my trail:

Original Issue:
1. Crank with no Start. No pulse to Injectors with NOID light. 40psi fuel pressure at rails

[/U][/B]Replaced:
1. ECM
2. IAC
3. Engine Wiring Harness
4. Plugs
5. Wires
6. New Distributor/Cap Rotor
7. New injectors, all 8
8. MAF
9. Oxygen Sensor

After these parts were replaced, The car would crank AND start but then I began experiencing significant idle surging and frequent stalling with no start issue when I would stop at a traffic light or stop sign. When this occurred, the car would not turn over for several minutes to several hours.

After my last post I purchased and replaced:

1. A new EGR Valve
2. Replaced all EGR/fuel pressure regulator/emissions vacuum hoses/connectors
3. A new MAT sensor
4. New upper manifold gaskets
5. New TPS

While doing this I also:
1. Removed the Fuel pressure regulator and checked it by applying vacuum to the diaphragm and watched to ensure no leakage or loss of vacuum. No issues identified
2. Removed the EGR solenoid and cleaned it thoroughly. I tried to find a new/replacement one but no luck so I reinstalled it as is.

*Note: The Egr was not "stuck open or closed" and the diaphragm was able to move however it was very difficult to move with my hand when applying medium pressure. Compared to the new one, I would say the old diaphragm was significantly harder to move so im guessing that the vacuum may not have been enough to adjust it.

SUMMARY:
The car cranked over and she started right up, no issues identified and I drove her most of the weekend with no stalling or no-start issues "yet". If you are like me, you have said that every time you replace something new only to find a week later that you were sadly mistaken. So I will update everyone again in a week or so and let you know if she is still running without issue. Thanks for everyone's help, this community rocks. Hope my experience is able to help others like myself before they end up replacing everything like I did.

NCC-2569

iTrader: (1)

Hoping for the best here

89gta22

Well, the boogie man is back. Took the car on an hour road trip today, drove fine good idle, great power etc. Stopped at my destination, then started it up to make a quick run to the store and noticed the idle was erratic. Not terrible but about 800-1200 rpm and I could hear the engine surging in waves. Occasionally I watched the tach even hiccup and dip sharply every few minutes. Second traffic light I stopped, Boom, she stalls. Unlike all other times I was able to quickly get her started again by cracking at WOT, but not more than 10 minutes later she did it again. The second time I got a code 32 for an egr system failure. I checked the lines, to make sure nothing had happened and started it back up and the light was no longer on. Odd......

Per all my other posts in this thread, I have to assume that whatever is causing this chronic and intermittent issue has still not been resolve yet. Also, it's unusually hot today and the car was running about 200, normal given my 180 thermostat.

The only remaining egr component not replaced is the egr solenoid which is my top suspect give The code 32 after the Second stall. Otherwise I'm out of ideas....... Anyone else with an egr solenoid problem seen these symptoms, particularly when the engine is at temp???
Please help!

89gta22

Hi All,

Per my last post I experienced a few additional odd issues that I wanted to share. While test driving the other day around about 200 degrees on the dash the idle started surging and then suddenly the car cut out, check engine light came on, and Rach dropped to about 200 rpm. The first time it happened the car stalled and would not start again. After waiting 5 minutes she started up again only to have the same thing happen 2 miles down the road. The second time however when the engine cutout and check engine light (code 32) came on I quickly floored the accelerator, and suddenly the check engine light went off and the car got power back again. Weirdest thing I've ever experienced.

After getting home I followed the diagnostic manual for code 32 EGR system diagnosis. I need some help here in resolving the issues I'm seeing because they don't make any sense.

1. Unplugged CKT 935 which is the egr temp sending wire (dk grn) and grounded it. At idle probed with test light and got no signal? My understanding is that the temp sensor grounds when at temp and that that wire should see juice when grounded. If not is this an ECM issue?
2. Grounded ckt 935 and pulled vacuum line from egr. My understanding is that when ckt 935 is grounded the ECM sen a signal to the egr solenoid to allow vacuum to open to egr valve. However when ckt 935 was grounded the egr did not see vacuum. Confirmed the vacuum line to the solenoid which connects user plenum did have steady vacuum supply.

Can any one help me with this diagnosis? I assume I have either a bad egr temp sensor and/or bad egr solenoid, however I'm confused by the signals I'm getting with my test light. Any help would e much appreciated!

rusty vango

you should have brian of "tuned performance" burn you a prom . may be the end of your problems. it worked for me, give him a PM

Dakota W.

He already replaced the ecm, so it's not the prom or the ecm. It appears to be an issue with the EGR, hence the code 32.

To the OP, since you've replaced everything else on the car, you might as well replace the temp sensor and egr solenoid, since that appears to be where the problem lies.

peterc005

Sounds like the fuel pump.

89gta22

Per my code 32 woes and the fact that this stall/no-start issues seems to be temperature related, I purchased a new egr temperature sensor and egr solenoid. Also, the egr valve I recently put in was one from autozone requiring the orifice washer and temp sensor adapter because the thread hole is too small. Since I am replacing all of the egr components I decided to see if I could find a stock egr valve and replace the cheap autozone one I just put in. Money down the drain but I'd like her to be as close to stock as possible.

Here are the parts I purchased:

EGR Valve:

Solenoid:

Temperature sensor:

*Note that these are not "direct fit" for a 1989 350 5.7 Trans am, Camaro or firebird, however they do fit the 1989 TPI 5.7 corvette. I was very confused by why the EGR valve and temp sensor would work for a 5.7 350 TPI with identical egr bolt pattern/channels, yet it lists as only fitting a 5.0 Camaro/firebird/trans am??? Also note that I am using a 5.0 EGR vacuum solenoid and not a 5.7 model because to my knowledge they are no longer available. Fingers crossed that this will work without issue.

Does anyone see an issue with installing these parts on a 5.7 TPI Trans am?

I am end the end of my rope with this car, lots of money invested trying to keep her on the road (and myself safe) but my patients and wallet are running thin. I know some people noted the ECM prom could be an issue. Is there any way to test the ECM prom to confirm it is functioning properly?

NCC-2569

iTrader: (1)

Your "patients"

You would have to hook up your ECM to a computer and keep an eye on what it does while driving.
This gives you the opportunity to look into the details after the car has stalled, for example.

Just another idea, probably totally unrelated to the issue.
I know from a couple of V6 Birds that they have this pressure sensor for power steering, so the car doesn't stall when you approach a curve in low RPM.
When this sensor was defective, the car would not increase engine speed to compensate for the higher load and simply die without warning.
Does your car stall in slow curves or when you're travelling straight on?

bop11

I don't think he did replace the prom only the ECM. He said he used the old one. Have you checked the alternator output? High output could be heating the ECM to the point it stops and then upon cooling returns to operation. The park/neutral switch, I believe, controls more than the ability to start. If grounded in drive, it makes the EGR inoperative and changes the idle.

rusty vango

IF it was one of their "street fire"coils .their offshore junk. they have known problems.

rusty vango

QUIT BUYING PARTS FROM AUTO ZONE!!! that decision alone could be half your problem.

89gta22

Hi All,

Back to the drawing board yet again. I installed a new egr temp sensor and per the guidance of many here, I replaced the autozone egr with an original equipment part.

The only parts on this engine/car not replaced now are the egr solenoid, ignition coil, and the prom. Everything else is brand new original equipment.

After installing the parts I went to take her out for a ride and again about 10-15 mins out she dies at a stop sign. No start with crank for 5-10 mins (same issue that started this nightmare originally) and then I was finally able to get it going again. Today I did an exhaustive test on her to understand this problem even better. I decided to let the car idle in the driveway for 15-20 mins and see what happens to be sure this was not motion related. Grabbed a beer and just sat and watched it.....not more than 15 mins into the show I could hear the idle change and become more erratic and then suddenly she just cut out and died. I immediately pulled the injector and tested it with a noid light and sure enough, no pulse. So it seems that whatever is causing this issue is causing a no pulse at the injector after the car gets up to a certain temperature.

What was even more odd was that after I let it sit for 15 minutes I left the noid light in while cranking, cranked for about 30 second with no nood light pulse and then suddenly I saw a tiny flicker at the noid light and then boom it started up and the noid light was blinking brightly.

So my question is, what in the world would make the injectors stop pulsing when the car is up to temperature or warm, and why is it that the injector plus intermittently comes and goes? I'm incredibly confused at this point, hoping someone can help. Could a faulty prom really be what has been causing all the issue since the beginning?

Another note. Someone mentioned the alternator before. I had not thought to check the alternator however I did notice today that the alternator is getting very hot. The dash shows a constant 13 v with no issue, but even after running for only a few minutes the alternator is almost too hot to touch. Could this be related?

Please Help!

rusty vango

yes, the alt. is a big part of it all .it has to be up to snuff. 108A is the required alt for a TPI car. now you say the injector pulse goes away after awhile??? ECM and/or PROM at this point would be my guess

84ws689bird

Check the Ground wire for the ECM. make sure it hasn't come loose or corroded. the injector pulse is a negative trigger through the ECM and if it isn't grounded properly, could cause issues... should be black with white stripe on ECM, might be two or more of them depending on year.. all grounds...

NCC-2569

iTrader: (1)

What's the voltage on your alternator when HOT? Does it drop?
Even if it does, the battery should be able to keep the engine running for a while without alt-support.
Heat can be caused by a bad ground. The cable on the alternator's rear side... is it in any way loose or moving about?

bop11

The alternator should not get that hot. Somewhere you have a short and it is probably overheating the diodes in the alternator. Could be the internal regulator in the alternator itself. When a diode goes bad it usually goes bad shorted and puts AC on the plus line. AC on the line to the ECM could cause it to shut down or be erratic. You need to put an ammeter in the line from the alternator to see if there is some big power draw. If not it is probably internal to the alternator. If there is a big draw you need to find it. Either way the diodes and regulator are now suspect and should be changed.

Dougs91Z

iTrader: (1)

89gta22, did you ever find out the problem to the no injector pulse when hot? My 91 camaro is doin the same thing when it gets hot, it cools and it will fire up.

89gta22

Yes, it ended up (after all that) to be my ignition coil. The cool was only a year old so I never thought to replace it, but sure enough, that was the culprit. I underestimated how much my unwrapped headers have been cooking my engine bay given all the sensors and electrical that are packed in there. Start with the ignition cool if you have gone through all the same pain I went through in the tread (or start by swapping in a new one to save yourself a ton of money). Good luck, let me know how it goes.

Dougs91Z

iTrader: (1)

My car has bad injectors, I removed the pigtail on the worst one (5.4 ohms) and it fired right up when hot. Just ordered a set from South Bay injectors.
Thanks guys!

89gta22

Great! So glad that the thread helped. Can't tell you how many times this community has saved me.