Ford expedition, 99, 5.4, has been idling rough and stalling. I received a p0171 bank 1 and p0174 bank 2. I can hear an air leak but not sure where. Aside from that, I recently changed the heater core, but now smell slight coolant. could the 2 be related or is it just the fuel filter?
Those codes are for the oxygen sensors, lean fuel mixture on both banks. Change them, problem with stalling and rough idle should go away.
The sensors are just screwed into the exhaust pipes.Unplug the the wire connector, use an oxygen sensor socket, or wrench, if not in a tight spot, and unscrew them.
Also disconnect neg. battery terminal, before you unplug them.
If there is an anti theft feature built into the radio, better get the code for it, cause once the battery is disconnected, you will loose preset stations, and it won't come back on.
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how do i replace the oxygen sensors? and should i replace the pcv valve also?
Could the Mass Airflow sensor be the culprit?
Thanks for all of your help!
Just an update: After taking a closer look and following the air leak sound, we found a big hole in the Elbow of the PCV valve.... when we covered the hole, the idle was normal again! Hooray for that! Unfortunately no one sells just the elbow... had to put out $65 for the complete assembly... oh well. Thanks again for your help.
where is bank one
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