I’ve had quite a time with my 1993 coupe. I can’t believe I’ve had it for 10 years now. A few years back, after some happy thousands of miles of driving, I got the SES and a code 36. Although it was still running, I tore into it to replace the opti. Bought a new GM opti and water pump as well. Car was driven only occasionally. About 500 miles later. It quit. No fire at the plugs. No codes. Because of the low operating hours I looked at other things, after all, it couldn’t be the opti. Also, no codes like before. Lost my job. Put the car in storage, because I had to move far away to find work. It sat there for a year and a half. After I was finally able to get it out, I carried it to a mechanic. Replaced the fuel pump, spark plugs, and yep, you guessed it, the opti. Although I found out later things were done somewhat unscrupulously, I think he just put in a cheapo opti from Auto Zone. Here I am about 200 miles later with a code 36, again. I also get a code 12 (initializing), and code 15. My book skips over code 15. What is that? I can’t believe my bad luck. The car cranks up and runs. For a while, then quits. I go back later, and it will crank up. I read in some other post that the bearings for the shaft that feeds the opti can go bad. Has anyone done this procedure? How difficult is it? I have to wonder what I’m missing. Any advice appreciated. Also, where is a good place to buy a GM or otherwise long lasting opti? Car has 101K miles now. Had 62K when I bought it in 2000.

 

It is possible that your opti wire harness has corroded, pull that and give it a look. But, unfortunately it does sound like you have another bad opti. The Gen I non-vented optis don't hold up to well from non-use and the moisture that builds up. I went through 2 Gen I optis by 20k miles on my car, at that point I upgraded to the Gen II vented opti.

To change the opti shaft you will need to pull the front timing cover and remove the top timing gear. It's a pretty big job, and it is very rare that the bearings go bad.

 

I agree to check out your wiring, connectors and pin connectors. But I would consider the possibility given your symptom that the ICM might be causing this problem. Sounds like it's temperature related and ICMs are known to just shut down when hot and then come back to life after cool down.