Yeah, it's modified. The egr and air were removed. I now have pacesetter long tube headers with an off road y pipe straight back to a flowmaster 40.

Icm tested fine, but there was a spot on the mount/heatsink thing that had thermal compound missing.

 

icm could be failing when it gets hot.

 

Is there an easy way to check an ignition coil? I've compared mine to pictures I've found and it's... questionable.

 

old school scope. not so sure on the new electronic diagnostics out there, went to auto school in the 70s. lol.

 

Thought this was a pretty good video.

 

Still having the problem, and it's getting worse. Checked all the wires today, they're still good. I replaced the plugs recently but I plan on pulling them just to check on them. I got my obd2 cable for my laptop today and took a couple screens for you guys.

One code snuck by me, it's the one on the very top. Can that cause a miss?



I'm gonna read up on the proper values, but I doubt negative ignition timing is a good thing?




And I appreciate you guys putting up with me.

 

Your temp sensor could cause some funny behavior though. Also, the manifold leak can create a vacuum problem. I had the same issue with mine. Fixed the manifold leak and my rpm fluctuations went down drastically. My opti problem started similar, random flare ups now and then gradually getting worse until it was literally stuttering and 'bucking' all the time throughout all rpm ranges. Manifold leaks down onto opti and gets into it fouling it out.

 

I'm leaning more and more towards the opti. Felt like I was riding a mechanical bull today.

 

i see you had a -40 degree temp on that first scanner. that will make the motor run very rich. the timing could be knock sensor is failing and hearing something thats not there. or could be hearing an exhaust leak if you have one, or if you have headers. or could be opti. or could be injector but i dont think it would show as a misfire

 

As soon as the car cools down I'm gonna check my fuel pressure to rule out a failing fuel pump. It's new, but who knows.

I replaced the temp sensor, but I'm still getting the same trouble code. My wiring is pretty messed up. I'm thinking about replacing the wiring harness.

Does an "engine wiring harness" include the wiring for everything in the engine bay? I ask because there are multiple versions on ebay. Another question I have is if I can use a different year/transmission. A local guy has a harness for a 96 lt1 with an auto transmission. I have a 6 speed.