Well, it looks like my problems are fixed (at least for now). I took the car out for a test drive today and it ran great! Im not sure how to put this post together so its easy for people to trouble shoot their own cars with similar problems but here it goes.

The short version is the car started to gradually stutter, stumble and backfire. It started at upper RPM’s and the longer I drove the problem would work its way down to idle. Eventually the car would only drive for about 20min then it would start to act up to the point it was nearly un-drivable. I would have to let it sit for several hours before I could drive it for another 20min. Only twice did the car throw a code, it was DTC 36.

First I thought it was a fuel pump issue because it felt like it was running out of gas but would never die plus I have a full tank. I checked fuel pressure and injectors and even put some fuel system cleaner through it. This obviously was not the problem.

Then I turned my attention to the ignition system. I replaced the coil (it was in bad shape) and the ICM with little luck. With the help of the guys from this site I narrowed my problem to either the opti or the O2’s (I know, not part of the ignition). I rolled the dice and went with the new AC Delco opti from Summit. I replaced the opti along with the plug wires.

Even though I replaced two parts I feel the problem was the opti and the car ran very well this evening. I drove for at least 30min back to back with no problems. The car feels like new, well as much as a 93Z with 140K miles and no major repairs to this point; knock on wood.

Below are some of the posts I used during trouble shooting. Hope this helps someone.


https://www.camaroz28.com/forums/sho...d.php?t=691122
https://www.camaroz28.com/forums/sho...d.php?t=695265
https://www.camaroz28.com/forums/sho...d.php?t=699082
https://www.camaroz28.com/forums/sho...d.php?t=689802
https://www.camaroz28.com/forums/sho...d.php?t=594312
https://www.camaroz28.com/forums/sho...d.php?t=545752
https://www.camaroz28.com/forums/sho...d.php?t=693483
https://www.camaroz28.com/forums/sho...d.php?t=695158


Sorry this is so long but I hope it saves at least a few from going crazy. By the way, this job was not that bad in hind sight. I think the plug wires were the worst part.

Good luck and thanks for all of your help!

Matt