Misfire Question

[speedzonwheels]

I have had a misfiring problem for a bit now. I have done a full tune up on the car lately and still have the same problem. When the car is cold, the vehicle runs excellent. But once up to normal temp., the car runs like crap. I put the accelerate pedal to the floor and it bogs down and misfires badly. I also noticed when its cooler at nights sometimes, it runs fine and seems to be at the same temp, maybe a few degrees cooler. But anyone got any ideas? I have a 96 firebird with the 3800/M5.

[98Camaro3.8]

What have you done to try to fix it?

Higher octane fuel
Air filter
Fuel filter
Sea Foam
Plugs
Wires
Coils
Fuel injectors
ICM
FPR
Fuel pump

[speedzonwheels]

I have replaced the air filter, fuel filter, plugs, wires, coils, pcv valve, ran octane boost thru the system many times to make sure the fuel systems cleaned out. That usually gets the injectors cleaned up. Also have bought one coil pack and put it thru on all 3 packs to see if maybe one was acting up. The car runs fine eiether way when i run the vehicle normally. But under a load when its warm, the car won't run right for crap.

[99davenport]

do a voltage check on the coil packs when the car is warm and misfiring. The wires to and from it might have some resistance in them and when they get warm it greatly increases resistance. also it might be a bad valve alot of times you will have carbon caught on the valve and it will cause misfire. Is the misfire is only one one cylinder this is most likely your cause and don't run it anymore until its fixed, it can cause bad internal damage.
sorry bout the bad grammar i am in a hurry ;)

[99davenport]

o yea and check all your vacuum lines and tighten them it could be a vac. leak

[Fbody3400]

Sounds like maybe the wires are getting heated up once the car has been on.