I retrieved the following codes, P0171, P0173, both codes report lean STFT from the 02 Sensors. Both sensor banks show similar readings. It occurred while driving a about 60 mph, with engine temp 186 degrees. After unplugging the MAF sensor I received a P0102 DTC, which makes sense because it has been disconnected.
I have done the following checks:
1. Sprayed carb/choke cleaner on all vacuum lines and no leaks detected. OK
2. Check fuel pressure (4x) on incoming side and got stable readings close to 40 psi. OK
3. Replaced PCV Valve. OK
4. Replaced fuel filter. OK
5. Did compression test on engine, all cylinders approximately 200 psi. OK
6. Inspected, cleaned, and regapped spark plugs. OK
7. Replaced MAF, and MAP. OK
8. IAC inspected, very clean, and appears OK.
9. ECT sensor shows good temperature reading when scanner is linked.
Engine is completely stock, OEM.
When I unplug the MAF the engine runs significantly smoother. When I plug the MAF back it it runs extremely rough, surging, and eventually stalls.
I don't have spare ECM to try and switch to see if it is the problem. I am considering based upon mileage to change the 02 Sensors and have the ECM rebuilt and reflashed.
Does this sound like a logical plan based upon my observations?
Monday, December 31st, 2012 AT 1:54 AM