I just bought a 1993 3.4 automatic camaro that has a misfire under a load,,mainly like going uphill,,idle is perfect,,and when i'm going uphill it will spit and sputter and backfire a little and straighten out for a little bit,,i went to check for any codes,,service engine light comes on but doesn't blink any codes at all,,nothing not even the normal code 12 light just stays on,,so i was told that this could be a computer issue?? any ideas?

 

are using the "jumper" method to check the codes? because from what i understand, it doesn't work. i would inspect plug wires for cracks or whatnot.

 

Misfire under load is usually due to either an ignition problem (plugs, wires, etc..) or a lean fuel mixture (low fuel pressure, O2 sensors, MAF, ECT sensor)

 

ok,,today i bougt and installed new plugs and wires,,,test coil packs and was good,,it made a difference i thought,,but still had a stumble and backfire although it did run much better,,feels like its loading up with fuel and because as long as your in it good runs great,,just easing around and then give it gas it wants to stumble for a bit pop out the exhaust a little then take off normal again,,like i said as long as your in it runs good,,ideas??

 

Oddly enough I have a 91, but it's got the v8 5.1, and it's doing the exact same thing. Any advice for that? Me and my grandfather have replaced just about everything minor on the engine, even adjusted the tranny, a replaced a few fuel sensors, and adjusted the fuel/air intake for a more robust mix, but it doesn't seem to help.

 

I am having the same problem with my 3.4 as well. And if you search this forum many people have had the same problem. My mechanic is going to do a compression check next week on my engine, I'll let you know what is going on once i find out. He also says it could be the valves. Your problem will slowly get worse. I had no codes as well, and I think if you have the right computer all you need is a special key I believe the "K9" key for the computer to read it correctly. Our camaros (the 95 v6 3.4) had an obdII connector with OBDI diagnostic.