'99 Expedition XLT
#1
'99 Expedition XLT
Hello everyone I'm new to the site and was wondering if you guys& gals could help out with some knowledge about the trouble codes P0302, P0304, P0420, P0171, and P0174. I know at least 2 codes are misfires, courtesy of google, but the others have brought about several different answers. Truck has started to idle and accelerate very roughly. All info and recommendations are greatly appreciated.
#4
#5
For the P0171 and P0174 both banks lean, check the rubber elbow at the back of the intake manifold coming from the PCV valve and check around for any other vacuum leaks. You should try cleaning your MAF sensor too. The misfire codes are cylinder specific. The P0420 is probably from the misfire, but get under the truck and check your O2 sensor wires and connection anyway.
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HappySailor
Modular V8 (4.6L, 5.4L)
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04-09-2015 08:54 AM