Rexracer77

Hoping to get some help, I'm sure there is an answer in here somewhere, but can't spend hours reading to find a similar situation.
For reference 92, LT1 built 383, ZF6, was built 10 years/30k miles ago so proven track history, nothing done recently.

The story.
Last night went out for a country drive to the top of the hill, decided to cruise through all the fancy hill houses on the way back down the mountain. Was idling along, using the engine braking instead of dragging my squeaky race pads through the neighborhoods. Suddenly the engine died, but engine compression kept it spinning, but tach went to 0. WHile rolling along tried to restart it, cycle off/on, nothing. Got the car pulled off the road safely.
At this point I will say I have had a starter heat soak problem, where the car wont crank or crank hard when warm, but I think I have 2 un-releated problems here

So when I could get the car to crank and start it would run for 1-2 seconds then promptly die, no sputter and die, but die like the ignition was shut off. repeat a few times, reving it up thinking it maybe a idle issue, but no, it would die at 3k RPM boom dead. So i went for a walk, and came back after 30 minutes or so. I got the car started, closed the hood and started down the hill, after about a mile, same thing boom dead.

To add to the problem, being the end of the day, my cell was dead at this point, and no charger cord, so I ended up walking 5 miles home, at midnight.

My mind of course went to the Opti, but from what reading I have been able to do, no one else has mentioned that.

I am hoping when I go back to get the car this afternoon, being cool it will get me home, but maybe not. Haven't had a chance to pull codes, but didn't notice a check engine light when I did get it running.

Any ideas?

Klondike

Kind of the way one of my Opti's died. Just shut off and would restart after a few minutes but die again in a short time. After sitting overnight, it would run just long enough to get me about 5 miles from home before it died again... Managed to get it back home after a couple of cool downs and replaced it (again) The high dollar MSD didn't last as long as the $100 E-bay cheapie on it now!

emptnest

Sounds like the Opti.

rklessdriver

While it could be the Opti itself I would suspect the Ignition Control Module (ICM).

First I would pull the codes and see what they tell you.

You can trouble shoot the old school way once it gets hot and shuts off, to verify it's an ignition problem by checking for spark at the coil.

If no spark, then you can then trouble shoot the ICM, Coil and Opti by checking the voltage on the pins of ICM connector using the method describe in the below thread.

http://www.camaroz28.com/forums/lt1-...d-opti-601565/

Will

Rexracer77

Thanks for the feedback.

Added information, at lunch I took an extra rig up to where I left the car. Started up fine, idled, so I drove it home no problems at all.

I forgot to say, it died like this one other time, months ago, same sort of situation, Sunday evening drive, came back, and idling through neighborhood suddenly died, like turning the key off. Wouldn't start. sat for 1-2 minutes, then started up and i drove the last 300 yards home. Hadn't done it since.

Rexracer77

Also, since it died in the same way, idling along, using engine braking to get down the hill, is there something about this type of driving that would heat things up to cause this failure?

Rexracer77

Anyone else have any ideas? I realized I could at least try swapping the ICM from my 94 to see if that changes things, though the problem isn't happening consistently..yet..so hard to know if I found a solution or not.
I hate having a car I cant rely on...

antfarmer2

Test the icm and coil. Coils die when hot as they say goodby. Clean and check connections too.

Rexracer77

Bump - to see if anyone has any additional ideas.

SELLC

I'd plug it into a scan tool and see what signal is blipping out...

TPS? Ignition? Also there might be some tell tale codes.

Also could be something as simple as the battery terminal being loose or stripped.

Wish I could say with certainty. I'd start checking sensor outputs when the problem happens. A fuel pressure tester might also prove to be helpful if you get nothing back from the computer.

Rexracer77

Ok had a chance to play with this some more.

I had some other stuff to do, so ordered a new coil since they are cheap. Once I got the correct starter and everything got it running and took it to work. Instead of a problem after a long drive, it died in the same way after about 5 minutes.

I left it on the freeway onramp, walked home, got my other car and went to work. After work i walked back, it started right up, and I drove it down to the next exit (to make a big circle) and sure enough after about 5 minutes it died again. I sat there for 15-20 minutes letting it cool, but that wasnt enough and it wouldnt stay running. (starts but dies as soon as you left off the gas). I walked home, and then late that night walked back and drove it home, it died pulling up to my house.

So I figured I was on the right track, and ordered a new ICM (found one on Amazon for $36). Installed that, and BAM, now it wont even run for a few minutes, it dies right away. If I am PRESSING the gas, it runs, but as soon as you let off the gas it dies. I mean pressing as in adding throttle, not just holding a constant RPM, but climbing RPM.

TLDR:
So Coil made it worse, ICM made it even worse. Seems like I am on the right track, but not found the source.

Ideas?

93VettePilot

Check the fuel pressure and see if the fuel pump is on its way out. You can drive around with the hood slightly open and duck tape the fuel pressure tester to the windshield so you can see it while driving. It should be around 40psi but it fluctuates with vacuum. Autozone has the correct fuel pressure tester in their rent a tool program. Its the easiest and first thing to check.

VikingTrad3r

Uah. Have tou gone theough the usual suspects like fuel pressures? Id like to see what the fuel pressure is doing when it fails. And also while you are trying to start it afterwards when you say you need the foot on the gas. As mentioned. Tape to windshield.

Mateo Ramirez

Similar thing happened to me. First the fuel pump. The second time was the ICM and Cool. Once I replaced those it was better. I know the pain. Also what a trooper walking home 5 miles. I called a tow truck asap...

Richard Raichert

That is exactly how mine acted. Run great, quit, let sit for 2 minutes it would start rev up to 3 thousand rpm and it would shut off like a switch. Sit for 5-10 minutes and it ran good to get home always looking for a place to pull off! Finally it quit while driving 35 mph. Mine was the opti and Icm replaced also. Frustrating for the month that this went on until it quit for good.

Rexracer77

So I finally had a chance to go borrow the fuel pressure gage from Autozone.

key on pressure goes to 44psi, crack start holds solid, stabbing the throttle to make it run (since if i am not adding throttle it dies) it would drop to 38psi, but jump right back up to 42-44. When it dies, the PSI holds solid.

So I am thinking its NOT fuel related, especially the way it dies, if it was fuel starvation (low pressure etc) it would sputter and die, but this is like turning the key off, it instantly dies.

I talked to Tom Wong yesterday and he instantly said Opti, so looks like I will go there next unless someone has another idea.

Thanks for the help!

9T3VETTE

Could be the ECU??? When my ECU started to crap out it wouldn't die but acted all sorts of weird. Running rich, no power, couldn't get RPM to increase etc.
Seems alot of ECU problems are heat related so it may be something to look into.

Good luck, let us know how it turns out

TorchTarga94

Have you pulled the codes yet?

Most likely the Opti

Rexracer77

Yeah C12, H16 and H41

TorchTarga94

H16 is a stored Opti code my brotha. Before you dive in, check the voltage at opti harness test connector (passenger side intake manifold) as outlined in the FSM. This will rule out any issues with the wiring. Also, check the ground strap that runs under the brake booster. Clean the connections if need be. Also check the ground junction at the bell housing bolt above driver side cat. Clear the codes through the DIC. If H16 rears its ugly head again replace the opti.