Ive had an on going issue (the past 2 months) of my car not starting every time. It will crank and crank (sounds like the starter is getting plenty of juice) but wont start. Ive done shoe boxes ICM voltage check, and everything was fine with that. The opti has less than 5k on it, and its a gm replacement part. I don't have access to a scanner cause of the obd 2 port. Some times it starts right up and runs fine, some times it starts and dies. Im not getting spark at the coil or at the plug wires. I had it flat bedded to the transmisson shop because the trans needed to be rebuilt, and of course they had no problem getting it started. They did check my alternator though and said it wasn't always putting out correct voltage. They said thats the only thing they found wrong with the electrical system. IS THERE ANY WAY THAT AN ALTERNATOR ON THE FRITZ COULD CAUSE THIS RANDOM SPARK/ NO SPARK START/NO START CONDITION?

 

Even if the alt was not putting out, as long as there was decent battery voltage, the car should start. Check wires/connections at the ICM and both ends of the coil wire.

 

shoebox, thanks for replying. I did all of the voltage tests at the icm like it says on your sight. Everything was correct. thats why this is so frustrating to me. I really didn't want to just throw new parts at it until its fixed, but looks like thats what Im going to have to do. Also, the fuel pressure is correct, so thats not it.

 

If you are getting good signals to the ICM and no fire from the coil, it seems it either has to be the connection there, ICM or the coil.

 

So, theres no way that the opti could be giving correct voltage intermitently? If those are my 3 options, its the ICM, because The coil is good for sure.

 

It could be, but how would you know if when you test it, there is a signal? Intermittents are the worst to track down. You would get a trouble code, though, if the optical section of the opti was intermittently failing. The low res code does not cause the check engine light, so you would have to scan it to know.

 

need to scan for data. need to see if the scanner is picking up a cranking rpm. somewhere around 200 rpm is good.

 

I recently had the same problem of not starting on my '95 Z. I followed all the ignition voltage checks too and found no problems. However, in desperation I took the ICM to AutoZone to have it tested and it tested bad. Put a new one in and she fires right up.

I don't question the ignition check procedures as posted on Shoebox's site, I figure I missed something.

 

What is on my site does not prove anything through the ICM-just up to it.