collum

i had a set of heads put on a couple weeks ago and noticed that the car had been running rich(plugs, valves, and pistons all black) so i bought efilive and when i read my current tune my previous tuner had set my pe vs rmp from 3600rpm and up 10.8afr so i leaned it to 12.2 but the problem is that it slowed the car down and was not getting anymore kr so does anyone know why i would be loosing power with the car leaned(but probably still to rich)i switched between my old tune and the new(only thing changed was the pe) at the track and mph was down w the new tune, also my o2's are reading 930mv with the old tune and 880mv with the new tune i put on, but like i said it seemed it was making more power rich, also i made multiple runs both ways but the car seems like it is running slower than it should both ways best on motor was 12.1 and nitrous 10.9 at 125 mods are in sig any help would be appreciated

cam 222/228
heads ported ls6
intake ls6
fuel pump 255lph
trans 4l60e

half-n-half

iTrader: (7)

http://forum.efilive.com/showthread.php?t=2613

this thread explains PE...
you also need to check what your commanded AFR is at because the computer is going to use whatever is richer... commanded or PE.

Louie

collum

commander afr was 11.4 old tune and 12.2 my tune according to my scans

SSpdDmon

iTrader: (10)

Yes....but what your car commands and what actually happens are two different things. There's no way for the stock PCM to tell your AFR at WOT - only during cruise. It sounds like the guy who tuned your car just tuned WOT by manipulating the PE table to get your AFR in line (which isn't exactly the right way to do things). By leaning out your PE table, I'd be willing to bet you're running over a 13.5 AFR....especially since you said you slowed down. Ever watch an Indy race? They have dials inside the car to adjust the AFR for when the need to conserve fuel. When they lean the motor out, the lap times increase - but fuel consumption goes down. That works for them because the rebuild the motors each race. Our cars on the other hand need the right AFR at WOT. So, I'd highly suggest getting hooked up to a wideband O2 sensor so you can read what your AFR really is. Then, learn how to tune and do it right unlike the guy who just "patched" it up.

collum

i was going by my stock o2(i know not as good as a wb) voltage on both o2's over 920mv on old tune