Ok, I'm stumped. I posted a thread awhile ago about my 1990 formula having a timing issue. I think i posted it in another section. Anyway, it's a 1990 formula tbi with a 5 speed manual trans. I inheireted the car from my mom. When she had it the front end was pretty much taken off in an accident. It was fixed, but since then It has had an issue with power. When I got it I noticed that under half to full throttle the timing retards to zero and it is an intermittent issue. does not do it all the time. I had it run on a dyno and after explaining what it was doing they hooked a timing light to it and sure enough the timing went to zero. They suggested a new knock sensor. Well, 2 knock sensors later, an est, esc, map sensor, coil, complete tune, and even a different computer, same issue. changed everything today, went for a test drive, and it fell on its face. I am at wits end. All parts that I changed were all oe parts, ie ac delco. It doesnt do it all the time, but close enough. Been chasing this problem for a couple years now. My question is this... Can the prom chip cause problems like this, as I had to use my original because its calibrated for my car, Or am I looking at a wiring harness issue? I am running out of ideas of what it could be, and was wondering if anyone else has ever heard of or dealt with this problem before. Like I said before, all ignition components are new, new coil, billet distributor, a new tps, and a different ecm. Any input would be most appreciated.

 

Ok. think I figured it out. Found a TSB (Technical service Bulletin) on the wiring harness on the 90-91 firebird. Would probably apply to camaros as well. There is a problem with the wiring harness rubbing on the firewall and a heater hose clamp because of the way the wiring harness is routed. Causes intermittent issues such as power loss, surging, rough idle, etc. All of my symptoms. Maybe some others are having this problem as well. Basically you need to check the wires, repair as necessary, and it should be good. If the harness is messed up by the hose clamp, loosen and twist clamp. I noticed the heater hose clamp on mine the screw is pushing right into the harness. Over time the harness will rub into it and chafe the wires. Hope this info is useful.