In my car when I get to about 7500 rpm the tach goes crazy, and the engine hesitates more than moderately. The next day my check engine light came on, it said it was the primary O2 sensor. Then the CE light turned off the next day, but the car still does the same thing. WTF? any help would be appreciated.

 

go to the dealer

 

I'm pretty sure I voided the warranty in one way or another so thats pretty much out of the question.

 

if you can get hold of another O2, try seeing if that's the cause...

 

Reset the ECU.

 

I already tried reseting the ECU

 

Check the ignitor. Many people have had problems with that going bad

 

I would take it to the dealer anyway, what's the worst they can say "you're warranty is not valid and we can not help you"