Hi All,
I'm doing some diagnostic info on my 2004 Monte Carlo LS with a 3.4L. Has 270k miles, so alot of things likely need replacing. I'm going through and trying to make sure that everything is operating as designed from factory, i haven't bought the credits to edit the tune yet, though i will in the future, but i'm trying to diagnose an issue with a lean condition under load. I had an EVAP large leak code, which i replaced the Purge Solenoid, the Vent Solenoid, and gas cap. That was taken care of. I was still getting LTFT over 20% under acceleration. I cleaned the maf sensor, and the throttle body with their respective cleaners. I sprayed down the intake with carb cleaner and found a small vacuum leak near the EGR valve. As this was the original EGR, I ordered a Delphi replacement for the EGR valve, even though i had no codes that required it. I replaced the vacuum lines and PCV valve as well, to make sure i wasn't missing anything else. After replacing the EGR valve, the car started throwing a P0404 code for EGR Valve Circuit Range/Performance Problem. The original issue of lean under acceleration still exists, though Idle LTFT went to the negative side and the Idle rpm came down to 600-700 from 800-900, so i believe the vacuum issue is taken care of.
My question is, should i attempt to clean the EGR, or just attempt an RMA for it.
The other issue i am seeing is the O2 readings on VCM Scanner are not matching. I'm including a log of a short drive if anyone can take a look. It appears as though something is adding around 0.4V to the baseline O2 sensor value, though when i look at the voltage reading from B1S1, it appears much more natural. It just appears glitchy in places and is something that i had not seen when i was working on my '13 Silverado. I Disconnected the battery for 10+ minutes in hopes the ECU would relearn the parameters for the EGR, but the P0404 came right back, and that is the scan that is attached.
Any tips for either the EGR issue, the glitchy issue, or the Lean under acceleration issue would be greatly appreciated.
Thanks,
Bigern
After Battery Disconnect.hpl