Re: 96 Camaro Z28 intermittent crank no start issue
 

Let's go over what's happening, now that you replaced the ICM and the battery, compared to your original post?

When you turn the key to “run” do the dash warning lights ALWAYS light up?

Do you ALWAYS hear the fuel pump prime?

Have you observed the “SECURITY” light when the car is not starting?

When you turn the key to “start” does the starter ALWAYS crank the engine? If not, do you at least hear a click? .... possibly from the theft deterrent relay near the glove box?

When the starter is cranking the engine, but it is not starting, what is the voltage indicated on the dash gauge? Extremely low voltage can extend cranking time and cause “no start”.

Follow up on the suggestion in the post immediately above. Corroded terminals at either end of the main cables can cause intermittent starting problems.

Re: 96 Camaro Z28 intermittent crank no start issue
 

Sorry for the radio silence, I was on vacation and kind of lost motivation because of my frustration. All of the grounds that are visible from the engine bay look fine, but I haven't had a chance to test anything because lately the car has been starting. A friend suggested to check all the solder joints on the pcm to see if there are any dry/cracked joints. I opened it up and to my untrained eye everything looks brand new; I gently tried to wiggle all the components and didn't see any solder joints that allowed for any play in the component. I'm aware of a ground from the pcm to the block that's down by the starter, but I can't see it to check it from the bay, and haven't gotten around to jacking up the car to look for it.

To answer your questions Fred:

When turning the key to run, the dash always lights up, regardless of if the car ends up starting or not.

I only hear the fuel pump prime when the car ends up starting. When I don't hear it prime, the car won't start.

The security light always does the same thing regardless of whether the car starts or not, which is lighting for about 5 seconds, then shutting off. It never blinks.

The starter always cranks the engine, no matter what.

As far as I remember, the voltage seems normal all the time, even when not starting. I don't know exactly what the gauge reads, I'll take note of that the next time it doesn't start.

Help
 

Re: Help
 

Re: 96 Camaro Z28 intermittent crank no start issue
 

Update: The other day I drove around a lot because the car started. It was hot out, so I came home and let it sit in the hot driveway for a little bit. Went to start it maybe 20-30 minutes later and it didn't start (fuel pump didn't prime, starter was cranking but engine didn't fire). Opened the hood and let it sit again with the hood open to try to air it out for another approx 20 minutes. Tried it again and it started, leading me to believe it was heat related. Drove around again, parked it in the sun and let it sit hot again. That time even after being hot in the sun for 30mins it started. Next day was raining, it started first time I tried. Drove around a bunch in the rain and let the engine get warm. Went home shut it off and sat in the car for maybe 2 minutes, and tried to start it again and it died completely when I went to crank it. Completely dead since then. Just got my battery tested again and it's completely fine.

Re: 96 Camaro Z28 intermittent crank no start issue