Hoping someone can shed some light on my biggest issue at the moment. Whenever i go full throttle, i get a misfire anywhere above 3k rpm, and makes the acceleration very inconsistent. There is no exhaust, and that makes it very east to hear. i have both put new cats and a new fuel filter in, thinking either of them would help the problem. If i ease the car up to readline, or hold it in gear, i dont get the misfire, its only when i really put the pedal to the ground. This problem has been prevelant since i first bought the car, and its getting frustrating since i cant figure it out. Any help would be appreciated!

 

What car/engine are you asking about. If it's a XJS you're in the wrong forum.

 

Its a 2000 XJR

 

Ah, an XJR. Your second fuel pump is failing.