Just finished changing out the opti, coil, and ICM on my LT1. I went with MSD opti, MSD coil, and ac delco ICM. I also replaced my 160* tstat with the factory 180* tstat. Of course I'm having problems....

On the first start it ran a few seconds and shut down. Did this a few times then it started to run fine....believe it had something to do with having the MAP sensor unplugged.

Anyways, it finally started running and i bled out the coolant system. Seemed to be working just fine...for some reason both of my fans were running. Decided to turn on the a/c to see if it still worked and just as it started getting cold the car chugged and shut down. I turned the a/c off and tried starting it again. after a few trys it started up. Went out and noticed the damn coolant bleeders were spewing out coolant!!! ah...what a mess. Tightened them up...sat back in the car and tried the a/c again and it shutdown again...i'll be damned but the SOB would not start.

I've checked everything...disconnected ICM and verified (key ON) 12vdc on pins A & D. A/C voltage on pin B while cranking 2.24 volts. Noticed on pin C (ground) it was 98 ohms....that seems odd right?

Disconnected the opti harness and verified (key ON) 5vdc on pins A and B; 12vdc on pin C....and 156ohms on pin D...seems odd right????

I thought that the grounds, pins C and D should be 0 right?

Regardless...i pushed the car in the garage and let it cool down for a few hours. I just went down to the garage and it started up...wtf???

I'm confused here. I know that PCMFORLESS did change my pcm program years ago. Would it have something to do with the temperature and changing the tstat? Or would the problem be with the ground pins C and D?

Someone please help!!!

 

Aren't the coolant bleeders right above the Opti Spark? I believe you got water/coolant in their and that is causing your problem. It happened to me. Mine worked after it dried out. However the car had a high rpm stumble that never went away until I changed out the Opti.