misfiring!!!!
Thread Starter
Teching In
Joined: Feb 2014
Posts: 34
Likes: 0
misfiring!!!! hi I have a 2001 ws6 m6. the only mods are slp lid, texas speed long tubes and 3 in texas speed exhaust. the car was running fine, and after a random restart i noticed a misfire. i changed the plugs and wires, and the o2 sensor on the left side checked bad, so i replaced it also. upon removing the plugs the 4 on the driverside are **** black, and the passengerside are dingy white. took car to an ASE certified shop and everything checked good,he said no vaccum leaks no bad sensors. thought it was the ecm,so i replaced it,got same result car runs fine when cold and skips when hot at low rpm. runs good at wide open throttle!!! please help!!!!!
TECH Senior Member
Joined: Apr 2002
Posts: 6,080
Likes: 17
From: So.Cal.
Airleak at LHS header collector (near NBO2) causes bank1 trim to add extra fuel to bank1 (causing plugs 1,3,5,7 to get rich/carbon fouled)... ASE certification does not cover long tube header collector leaks.
This is good info! Thank you for sharing. My car started missing today at low rpm, and no codes came up, either. I'll check my collectors for leaks tomorrow.
Thread Starter
Teching In
Joined: Feb 2014
Posts: 34
Likes: 0
Checked for exhaust leak, found a little **** around the o2 sensor. Tightened it up more car still gives code p0300 , any other ideas to try. I also put original ecm back in car due to the fact it was tuned for the long tubes, was getting codes for the rear o2 sensor with the stock ecm. Was also throwing p0300 with stock ecm.
