I know there have been a million threads on this topic but I am having different problems than my previous encounters.

Last January it was running fine and then one morning it wouldn't start. Searched on here, replaced the coil with MSD-8226 and it ran fine after that. 3 1/2 weeks later it dies again pulling into parking lot at work. I had heard some people didn't have luck with the MSD coil so I figured it may be that so I exchanged it for a new one. Low and behold it started up and ran fine for a while, until today.

It has been raining the past couple days, nothing extreme but it's very wet out. I haven't gone through any puddles and my car has been running normal. I wake up this morning, start the car and drive about 1/2 mile down the road and the engine shuts off. I coasted onto a side street and got the car towed home.

Is it the coil this time too? I haven't had it die while I am driving down the road. It's not hot out so I'm leaning away from the ICM. What about the chances of the alternator? I don't want to get a new GM coil and have it be the alt. vice-versa. This is my DD and I have work and class all week, I need to get it fixed asap. Thanks in advance!

 

my 94 z28 did the same thing start fine good power then die I changed the opti spark and its bin running good for about 2 years hope you have better luck

 

Battery was replaced in January too. I put a new GM coil in today, just cranks and doesn't start. No codes either.. Better not be the opti, it's the OEM one AFAIK and at 116k miles.

 

The ICM will get hot regardless of outside temp. It sits right on the cylinder head and can get VERY hot. Your problem sounds exactly like mine when the ICM was on it's way out. If it dies again, wait for like 10-20 minutes and see if it starts again.

 

Thing is I can't get it to start again...Couldn't have gotten that hot this morning it was running for a maybe 1 minute? I'm going to try and do some tests tomorrow to narrow it down, but I have class and work from 7am to 8pm.

Would it be worth relocating the ICM? I have seen a few members do that.

 

My car was completely cool one day, and I drove it for like 1 minute to the gas station. It died as soon as I left. If you do replace it, get one from GM.

 

I just don't understand why the SES light came on when the motor shut down, but there were no stored codes. It is doing the exact same thing it did when the last two coils went out; just turns over without a problem but won't start. Why aren't there any codes leading to the opti or ICM if they were/weren't at fault?

 

check your fuel pressure

 

The SES light always comes on with the key in run and the engine off, for the bulb test. Doesn't mean there is a code. When my ICM was going out it never threw a code.

 

Ah gotcha, didn't think about that. I'll do all of my diagnostics tomorrow, I just got home from another 14 hour day... Thanks for your guys' help so far, I'll post up some more info soon.

 

So after a few weeks of not being able to work on it I have done the following with still no start:

- MSD 8481 Cap and Rotor
- GM Coil
- EFI Connection Opti harness
- EFI Connection water pump harness
- New water pump
- New thermostat

All that is left is the ICM and the wiring between it and the PCM. I tried checking for 1-4V on AC while cranking but it didn't show any power. I may have had it set wrong, I'm not great with a multimeter. Why else would there be no power to it though? Shouldn't I have a signal to the PCM with a new cap and rotor and opti harness?

Parts not related but needed replaced because PO was an idiot:
-Felpro 1406's
-ARP-400-1210's
-R&D Speed EGR block off plates
-OEM coil wire
-NGK TR55's at .050"

 

Turned out to be ICM for anyone interested. Fired right up on first try after everything else was put back together. Runs better than ever now, I'm glad I did the extra work for the piece of mind.

 

if that problem ever comes back check your coil wires for breaks right where the enter the black and gray connector.i had misery with these.

 

That will be the next pigtail I replace. Mine already look creased and they are very stiff=brittle ready to fracture.