I've scoured multiple websites and forums for LT1 owners with the same issue and learned a lot, but I feel my situation might be unique enough to warrant its own thread. My 94 Z28 (Flowmaster 80 series exhaust, K&N air intake, Jet Performance module, a/c delete with underdrive pulley, 134,000 miles, rarely driven hard, all synthetic fluids, well cared for) is randomly dying on me. The engine instantly cuts out, no warning, with all electric power remaining. It's not constant, maybe twice a week, lasted almost a month without doing it after the first time (I thought I'd gotten some bad fuel) and only (so far) during the first ten minutes of driving. Once the engine warms up completely the problem seems to stop for the rest of that particular day. The problem hasn't shown up for the past week, essentially hiding itself from the mechanics so they can't precisely pinpoint it with a scanner.

Here's the list so far:

-Codes 32 and 34 for EGR and MAP sensor respectively, EGR valve still seems to operate normally (mechanics are adamant that these could not be causing the issue alone).

-The scanner instructed to check the PCM, but problem still couldn't be reproduced.

-Rack and pinion whole unit replaced 3 months ago.

-All fuel components check out so far, pump reaching 43-44psi under load, 39psi idle, fuel filter replaced just in case (which got rid of a oily sweet smell during moderate acceleration-WOT I thought was caused by the small rear main leak the car has developed).

-No burnt or loose wires, bad grounds, or vacuum leaks (don't really feel like paying for an engine harness).

-Alt is very strong, new battery, icm, cap and rotor, opti (installed 2012), and coils checked out (so far)

-MAF cleaned and Seafoam Spray Cleaner applied to the engine by me, tested the car on empty country roads and it barely smoked and ran like a race car which it still does 99% of the time

I still believe it could be a PCM or opti issue, since opti's have a wide range of symptoms (this would be my fourth, the first failed and the other two were taken out by a water pump and a flash flood). The Jet module could also be a culprit, so I'll be doing that bit of work myself since the mechanics won't touch it.

It's always been an exceptional car and problems with it are rare, which makes me worry more then usual. While the stalling issue isn't constant, I won't put anyone else or myself at risk by continuing to drive it regularly until the problem is 100% solved. Any help and/or ideas would be greatly appreciated. Thank you in advance.

 

Check your coolant temp sensor wiring. If you are able to scan your car see if the coolant temp reading to the pcm is not jumping all over the place. I had this problem happen while I was sorting my car out at the beginning of owning it. Made the car randomly want to shutoff, bog and loss of power. Hope this helps

 

Mine did the same thing. Was so random. I replaced the coil and opti. Not sure which it was, but it cured my problem.
https://ls1tech.com/forums/lt1-lt4-m...e-driving.html

 

You don't give any operating conditions when it cuts out. What's going on when it happens?

Trouble codes are stored, so anything there should be retrievable as long as the battery has not been disconnected and you check for them promptly. Some codes related to ignition don't light the SES, so check anyway.

 

Sorry I always manage to leave something out of a description. Operating conditions when it happens seem to be totally random. It's happened within the first ten minutes of driving at cruising speeds between 25-55mph, braking in a turn lane while pulling into work (happened right before stop while waiting on a passing car), and easy to medium acceleration from a stop light.

The only codes retrieved were 32 and 34. I'd been hoping for a code pointing to the possible ignition issue but no such luck.

 

Might check the EGR valve. It could be sticking open.