My car is currently cranking, but not starting. I've checked the fuel pressure and it primes to ~42 with the key in the ON position. I checked to see if I was getting spark from the coil when the car was cranking and the rare sparks were very small.

I decided to check the ICM plug to make sure the signal from the PCM was being sent. With the car cranking, I measured ~.3 AC volts with only small fluctuations at the B terminal. Is it supposed to always be between 1 and 4 volts when the car is cranking, or only when the signal to trigger the coil is sent from the PCM?

I have checked the A and D terminals on the ICM harness and they were both ~11.66v DC. Does this sound like the ICM is having problems or the optispark just isn't sending the signals? What else can I test to help narrow it down?

More info:
I replaced the opti spark about 3 months before this happened. Car died for the first time a couple of days ago, but used to restart afterward. It would die sooner if the engine was warmer. It was in open loop when it died. Computer didn't throw any codes (OBD-1).

I replaced the spark plug wires before it died and it ran fine for a couple of minutes until it sounded like it was running out of fuel/spark then died.

I recently replaced the coil after it wouldn't start just to make sure the other one wasn't bad.

 

i've got the same problem!!!!!

 

 

Are only the trigger pulses between 1 and 4 volts or should the voltage always be between 1 and 4. With the volts going near 4 during the trigger times?

Does my reading of ~.3 volts too low even if a trigger pulse wasn't being sent?

 

I don't think it will be a constant voltage, but wavering as the pulses come. Though, they should come fast enough that it might look constant.

I would not pay attention to the voltage when there are no pulses sent.

 

I was having a similiar problem in my '97 Formula off and on a few days ago. My car stranded me 2 times and I've owned it less than a week.

I managed to stumble across the fact that the weatherpack connection to the coil was bad. The pins were not making good contact. I actually had my arm down in the DS of the engine holding a plug wire I had disconnected near the plug to see if there was a spark; when the person helping me cranked the ignition, the car started. Scared the hell out of me. When I reconnected the plug wire and stood back, the car wouldn't turn over. Turns out I had been leaning against the wiring harness just hard enough to tweak the connector and force a connection when it started. Took it apart, bent the pins in the coil slightly up, and have been runnning problem free for the last 2 days.

Of course, I found this after having already replaced the Opti, coil, and ignition module. It's been a pretty frustrating 1st week. My 178,000 mile '92 Z28 has never left me stranded.

Hope you get it sorted. Electrical gremlins can be a bastard.

 

sorry I do not have more time to read all of your post. but this link should help. it will tell you what curcits to test on the opti, coil, ICM, etc etc

http://mainstreamtopics.com/forum/in...p?showtopic=78