07-12-2004, 09:17 AM
I recently put my stock exhaust back on and left the same map I had been running on the PFC. When driving around now I get WAY more knock in everyday driving. When I unbolt the muffler it runs fine, I dont get anyknock at all. But as soon I rebolt the muffler knock rears its ugly head once again. Also when driving around with the muffler unbolted the idle flutuates really bad, like I have a vaccum leak or something. It will fluctuate like 5 times then stabilize, almost stalling out. then when I rebolt it it will idle perfectly. My guess on the idle is that the PFC auto learned the idle with the muffler bolted up and when the muffler is unbolted the backpressure isnt enough. I will probably have to redo the auto learn idle again and unplug and replug the PFC and let the car idle for another 25 mins. As far as the knock goes I have no clue why the muffler would make such a difference in the knock.