I have a 93 corvette and Ive had it for a couple years with only minor problems.

I was driving the car to work one day and it cuts off suddenly. Im able to start the car again and get it home but then when i try to start it again it will cut off after idling for a bit. Each time I leave it idling it cuts off faster than the last time.

Finally it gets to the start where it will crank but not start. I check fuel pressure and I can’t recall the exact number but i remember it was within the specs I found or one off or something like that. Of course i couldn’t get it running so this was just priming numbers.

I then check for spark and got no spark on two separate plugs, put new plugs just to make sure and still no spark. I ordered an inline tester and plug it into the coil after a week and the car starts up to my surprise.

Ive seen lots of talk around the optispark but im unfamiliar with the system that much but the previous owner said the optispark had been replaced and the waterpump to prevent problems.

Ive also seen talk around the ecu? Some computer components at least and talk of the solder getting loose and can cause cutting off and even lights coming on like the srs, which I do have on but its been on for a while. For that I need to check the wiring at the rear driver wheel as I see thats usually the culprit.

What kind of diagnostics do I need to do from here? I feel like I smell a gas odor when starting the car and when it cuts off. I didn’t think to look at the tack as it died on the road, but it was def not sparking and now all of a sudden it is. Would this be a symptom of a bad opti? Any help is appreciated. I can wrench on most anything but my diagnostic skills are subpar at best.

 

 

I actually watched this and a lot of it went over my head, I can do basic voltage tests and stuff but I dont have a tool as sophisticated as what he used.

 

A 12 volt test light was used in the video…a 12 volt test light or DVOM can be used in lieu of a scope…instead of a 0-4 volt square wave as in the video you can see a 12 volt test light flicker or a fluctuating voltage of maybe 0.2 to 0.3 volts with a DVOM…you will not see 4 volts as the DVOM only averages the voltage and a signal like this with say a 50% duty cycle will only show 2 volts… if still over your head find a diagnostic shop in your area that uses a scope or even an auto electric repair shop.

 

Part of my issue with the first video was that I couldnt see where he was probing with the DVOM, based on the second one im guessing i test after the ICM going to the coil for the 2 volts?

Would it be a possibility that the ICM is overheating and thats why it shuts off faster each time?

I know I could take it to a shop but money is tight and although electrical currently goes over my head I know with time and help I can figure it out so I appreciate the help.

 

Sorry I took so long Ive been busy and the weekend is my only time to work on the car, but I pulled the codes and this is what I got. 1. H25, 4 H16, 4 H28, 9 H58, 9 H62, 9 H65.

I see two of the smoking gun codes you referred too so is my next step to replace the opti and icm or are there further tests to be done?

 

after resetting the codes and checking again this is what im left with
1c25 1h25 4h16 9h58