I had the same problem with my '87 Z24 hatchback years ago and it finally worked out to be the battery. Seems if the battery hasn't X amount of volts (15-18) if I remember correctly, the ECM will not function properly. Replaced the battery, problem fixed itself. Mine always had enough juice to start it but not keep running.

 

OK, Thanks. I'll recheck the charging rate.

 

15-18 VDC seems pretty high, typical charge rate at 1500 rpm should be 13.8-14.4VDC. Do you have TunerRT by chance to do logging?

 

Check to make sure your IAC is good, it is notorious for causing starting issues and dying problems.

 

I had a very similar issue with my 89 2.8L. Nearly identical trouble, would start find cold, after running it would start misfiring, eventually stall out and would not restart. It turned out to be injectors for me. They were shorting, and would fail when they warmed up. I tested them with an ohm meter and 4 of the 6 were failing or failed. I replaced all 6 and have no issues since

 

Fuel injectors are super reliable components. 4 failing at the same time is almost impossible unless you had a mutual cause like a contaminated fuel tank or something or a shared signal or power short. Maybe replacing the injectors gave you a temporary fix or maybe by moving wires, while replacing injectors, separated the point of contact where the wires were touching and causing a short. But I could be wrong.

 

I also had injectors fail under a heat soak condition until the eventually just gave up, swapped out all 6 and haven't had an issue since and that was probably 7 or 8 years ago now.

 

Afternoon All

1988 Z24, 2.8 automatic. starts cold runs for a few minutes then stalls. will restart but run only a few seconds. swapped out three good ignition control modules (behind coil pack) fuel pressure good at 40 psi, swapped out three good crank shaft position sensors, all connections appear to be good. My OTC scanner shows no codes stored or otherwise. When running all parameters appear to read well with in spec. Hopping some one has run across this, drivin me nuts. Thanks All
update, cleaned all the ground connections, seemmed to help, it ran for about 15 minutes this time and stalled. resulting in the same issue as above??? not a clue, ECM? Thanks for the help.

Check IAC valve. But also check the coolant temp sensor. It's possible that when warmed up the sensor fails by throwing off a seriously wrong reading which may be fooling the computer into send wrong pulse commands to the injectors. This can either completely stall the motor at specific temps or cause a complete no start if reads max negative temps when cold.

 

Problem with injectors failing on these engines is they are in banks so if one shorts it brings down more than one injector.