mustangchris09

WHich means both banks are running lean. I have an o/r x pipe i just installed with a tuner to delete to rear o2's, but i also have mil eliminators on the car as well thinking it would help but doesnt. Why am i running lean, bad front o2's possibly? Car never threw a code til the x pipe was on.

a_penquin

Could be the pipe itself, after I threw my catted one on I started popping "cat efficiency low bank 2" check your fronts just in case there is an issue with them. Also if you did plugs or any work by the injectors recently check the connectors, I had a loose one and it threw a bank lean code, but acted like a dead cylinder. Could also be the eliminators are reading as lean.

mustangchris09

yea, well nothing was done to the engine yet, just the midpipe and rear end work. I should note too that the idle is a little funny, will fluctuate and when you rev it up it slowly comes back down to 750 or so. sometimes it will even drop below that and the car revs back up by itself to keep from stalling.