gsxrjack

keep getting a lean stumble at steady speed/throttle and more so when i just back off the gas a bit (not fully comming off the gas) its getting worse and driving me nuts...car runs fine under power and im reading my A/F with an AEM setup....car runs its normal 14.6-14.9 at cruising, but then spikes into the 15s and i feel the stumble...it also stumbles a little at idle but i dont see the lean spike...my wide open is around the 12.5-12.7 range..

No codes and I have changed the plugs, wires checked for vacume and intake leaks..any ideas on what usually causes this..

car has headers, hi flow cats, borla exhaust and predator custom tune,

thanks in advance

jack

VetteTech81

An exhaust leak before the O2 sensors?

vettenuts

I was having problems with mine and just found that the coupler had split.

gsxrjack

long tube headers so unless a pipe or weld is cracked then everything should be tight upstream of the sensor.....ive replaced both o2 sensors and they dont coincide with the stumble...

gsxrjack

put the stock tune back in the car and the stumble is gone ....I may have had my long term banks way out of wack...just put in a new mail order tune from diablo (thank you sirs) and will try to tweak it in from there, using the predator and the aem a/f setup...

thats why i am glad i have the predator since there are only a few things that i can mess up...god help me (and the car) if i ever had a hptuner or one of those things that i could mess with every little detail of the engine it is also a good thing with the a/f meter so i can see if i get dangerously lean..

i know i said i put the stock tune back in but must not have :o