03 cobra misfire at wide open throttle

[justinhelsene]

I just purchased a 2003 cobra with 41000 miles. High flow cats, bassani exhaust, throttle body, cold air, pulley and tune by Paul's High Performance. I noticed it misfires/stumbles under full throttle. No check engine light, haven't checked codes yet. Changed spark plugs, no difference. Any suggestions? Possibly the tune? Seems to be worse with colder temperatures.

 

[Carbd86GT]

Have you checked the gap on the plugs? Out of the box, replacement plugs have too wide of a gap to them, they need to be closed down to .032" at maximum. Check them out and see what you have. If the gap is right, log alternator voltage as low output can cause a weak ignition system AND fuel system. After the alternator, you may have a fuel volume issue, maybe a failing pump, but start with the plugs first. Hope that helps, let us know if you have any other questions.

Thanks,