Ok, this may be long, but I am hoping someone can point me in the correct direction for what I want/need.

First off, let me say that Geoff at EPS has been a great help and I am just trying to get some more information before I call him back with anything that is trivial.

I had a 408 built for my car, 1999 Camaro Z28 M6. After the car sat for a while when the stock motor was blown to pieces, i believe this issue took place.

From 4k rpm's and higher, the car is an absolute beast. I am very pleased with it and it runs strong as hell. My problem occurs below 4k rpm's. When i am at a lower rpm than that and accelerate, the car runs terrible. Very choppy, sputters, and backfires. As soon as i hit 4k rpms, the car takes off like crazy, usually breaking the tires loose.

I sent it back to my engine and performance man, and he screwed with it for a while. He finally thought maybe it was a bad computer connection. He pulled the connectors and they were green and corroded. He soaked and scrubbed the connectors to get what he could get off and it helped a ton. I would say the car runs 75% better than before. Its stills does everything, just not as bad as previously. I talked with Geoff and he did strongly suggest a new wire harness and computer; which is where i was in my head anyway.

I need some pointers/advice on what im looking for. I went to painless performance and checked out their harnesses, but am a little lost. I would like a completely stock harness to just replace mine with if i cant do the following. What i would really like is a harness in which i can relocate the computer, i.e. the !wire mod, with more ease than a stock harness.

Secondly, I want/need a new computer, i believe its the pcm(?) that i need. Who carries this? Again, the car was tuned, so im not worried about any program for it because I'm sure geoff will wipe it out and put a custom tune on it as mine has now.

I am just very frustrated that I am so deep into this motor and car itself, and I'm not happy. I know it is neither Geoff nor my performance guy's fault, as i have TOTAL trust and faith in both of them, and they do work together a lot. I know its just my luck with this and the nature of the hobby.

Basically, if anyone has encountered my problem before, or have any direction to point me in, please, feel free to post. I just don't want to call and waste Geoff's time, or my performance guy's time if i can research before hand and go to them with solution ideas versus just a problem.

Also, do my number's sound right for a fully built 408, with forged internals, L92 heads, 92 mm intake and throttle body, and big cam that I dont have the exact specs to, running through an M6 with full exhaust.

 

Sorry to hear about your dilemma. Those numbers do seem a little low, but I would withhold judgment until you can determine if your problem is PCM related.

If you have the bucks, the RoadRunner PCM would not only be a replacement PCM, but you can also do tuning changes in real-time. Might help in narrowing down your issue.

Hope that helps a little. Good luck.

..WeathermanShawn..

 

Also, small update, I talked with painless performance today and their harnesses are not what I'm really looking for. Any ideas on a complete harness?

Weather, thank you. I will look into that.

 

Might be a dumb question but have your check spark plugs for cracks, maybe any tears and rips in the harness from hungry little fur ***** (rodents).

 

Personally no, when i drove it and could get on it, once broken in, i noticed the issue and brought it back to my performance guy. He was pulling his hair out and then checked the computer, to find green corrosion. I just feel that since he simply cleaned it and 75% of it cleared up, that is where my issue lies.

 

Look for a used harness in the FS section.