i have a 96 camaro z28 just seems like it loses power in the higher RPMS, i just changed out the optispark and plug wires the other day, helped out a little but has poor top end power! it has decent low end power but poor top end! before i changed out the optispark it ran perfect when engine was cold could spin tires first trough second but when it warmed up it ran like crap. now after i changed the optispark it runs smoother but doesnt have the power it did before when the engine was cold? any info would helpp!!!!

 

Is your check engine light coming on?

I would look at your sensors, especially your O2 sensors. Sounds like somethings not giving a proper reading when your car warms up and goes into closed loop operation.

Mine did the same thing. It would run good until it warmed up, then run terrible. After a few min of running bad it kicked on the check engine light it would run OK again. Turns out my passenger side O2 sensor was bad. Changed that out and its run perfect ever since.

 

Have you checked fuel pressure while driving? Might be weak pump or plugged fuel filter.

 

well it runs the same now while cold or warm sense i changed the optispark, but still doesnt really have top end power, i did have a check engine light on it was p1153 which im pretty sure thats bank2 sensor1 which is passenger side right? but then i cleared code and hasnt came on sense? so it might need changed still?

 

have you checked fuel pressure/ changed filter as mentioned above?

 

no havent checked fuel pressure yet ill do that asap

 

Do you run cats? Possible that one or both is plugged up?

 

yes but im pretty sure there is only one cat!

 

But if it's a 96, it left the factory with two cats. How did you eliminate one of them?