Engine Performance problem
2002 Ford F150 6 cyl Two Wheel Drive Manual 97000 miles
I am a long time certified auto tech and I'm at a dead end.
I have had this same problem for the past year or year and a half. My truck is throwing codes for O2 sensors being too lean. It isn't making sense. I have replaced the upper plenum, MAF twice, DPFE three times, EGR, and both pre-cat O2 sensors twice.
I have checked for vaccuum leaks and post-MAF air leaks. Found nothing.
I am still getting the same symptoms of racing at startup and surging (RPM up and down) at stop lights/signs (mostly when it's cold.
What might the next step be other than taking the truck through the dealership window?
Saturday, October 24th, 2009 AT 5:09 PM