[RJDRJ06]

My car died on me today and had to have it toed. Its a 72 Nova with a 94 LT1. Everything has ben changed before it was installed in car. I replaced Opti, plugs, wires, coil but I didnt change the ICM before install. I have 50PSI fuel pressure. I dont have any spark at the coil or plugs. Car does crank. I let the car cool off and tried to restart but nothing. Anybody have any ideas? Thanks for your imput.

 

[Workman]

You can have your ICM tested btw, but it would have been best to do this while its hot.
Also how many miles are on the swap? If the opti harness wasn't changed as well i could see this also being the culprit.
Ive noticed alot of cars on here that will start up cold with a bad ICM but as soon as they get warmed up, the car cuts off.

 

[cocobolo95]

shbox.com has a ignition system wiring diagram. Make sure coil and icm are getting power from fuse when ignition is turned on. USE link in post #4 as it is direct to opti testing.

When you wired your nova, did you put in the dlc and check engine light? If yes, hook scanner up and check for silent codes that don't light the cel. Dtc's 16- opti low resolution signal missing, dtc's 41 & 42- both icm related.

Go to sticky threads of this section and watch the diagnosing the optispark video again, as I'm pretty sure you've watched it before. Do the tests with the help of pages at shoebox's site which will give you the proper voltages and ohms readings of the connector wires of both opti and coil/icm.

 

[Workman]

Here friend try these. www.shbox.com/1/4th_gen_tech2.html#opti_test I had to type that out for u, im hoping if u cant see it correctly someone will post it to were u can. My phone sucks sometimes

 

[RJDRJ06]

Hey thanks guys. I ordered a new ICM and will try that first. Then I will try the rest of what you suggested. I will let you know what i find. Thanks again

 

[Roger Mabry]

Conversion issue - check that the ECM/PCM is grounded

Just went through a half a day of trouble shooting with the GM manual to find that the computer (ECM/PCM) was not grounded properly.

Moved it around a little bit and all was well. Took it off, cleaned the mounting
and added a braided ground strap...

Also, the Opti going out will give the same symptoms....

 

[RJDRJ06]

It's alive again!

Ok so I plugged in the new ICM without bolting it up and it fired right up. Holy sh&* . Love it when a plan comes together. Thanks for all the suggestions.

 

[Workman]

Sure thing man! If any more probs arise please feel free to post em. Were ALL always happy to help.