what would cause missfire,sputtering?

[armandovivoni]

hey people I need help. what would cause sputtering,backfires from 1,000rpm to 3,500rpm but then go to normal after 3,500rpm??

could bad valves do this?

timing?

barometric pressure sensor?

 

[sonicnofadz]

Perhaps you are running very rich? What are you using for fuel control? Do you have a wideband? (if not then get one)

 

[armandovivoni]

I have a microtech engine management computer. BUt the car was doing fine. this started happening after I reved it up to 6,000rpm yesturday. I tried leaning fuel mix. on lower rpms but this didn't fix the problem.

 

[zrk666]

check the wires and plugs, boost leaks and etc...