Just recently i did a full tune-up on my 1991 Z28 305 Camaro and my car is still misfiring. I got a new distributor, cap, rotor, oil, oil fitler, fuel filter, fuel pump, air filters thoroughly cleaned, spark plugs/wires, engine treatment(mixed with oil), vacuum lines somewhat cleaned with SeaFoam.

Any other ideas on what could be causing my misfiring? My car has 169,xxx miles. TPS and Oxygen sensor threw codes saying they were faulty. Someone recommended I check my wiring but i'm not really sure how to do this.

 

So why did you throw all those other parts on the car, instead of addressing the things you know are bad?

 

Because those aren't the major reasons for misfiring. It needed a full tune-up anyways.

 

Clear your codes out, drive it, and recheck the codes again. If its saying those same two items.....start there.

 

[quote=StephenS;540992]Because those aren't the major reasons for misfiring. It needed a full tune-up anyways.[/quote
Apparently what you think of can cause misfire is not what you changed. Misfire has many sources beside ignition, including fuel delivery, and maechanical problems. Both the TPS and O2 sensors if bad can make the engine run crappy.

 

Where is the OS located? When i put the new TPS on is there anything else i need to do to it?

 

It is not an OS sensor, it is a O2 (oxygen) sensor, and it is screwed into the exhaust manifold or in the exhaust pipe before the cat.

 

Sorry. I ment O2.

Well I do have a Hooker exhaust system and when i checked the Y pipe there wasn't a sensor. I can't seem to find it under the hood.

While I was under my car I did notice that my differential cap had this black looking stuff all around it, some was old and was dried to the rear axle and differential, some was fresh. The newer stuff was still wet and looked like oil and had kinda the same texture as oil. Not sure what this is but it's leaking on to the driveway.

 

Keep looking, the engine won't run too well without the sensor.
If you are talking about the differential cover, it may be leaking and in need of a new gasket.

 

Hopefully the oxy sensor wasn't left off when the new exhaust system was installed. That could, however, explain the misfiring and oxy sensor code.