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Dear:Eric
About a year ago i replaced the head in my car and now i get an error of P0171 .Could my EGR valve be bad I tested it with the car running and removed the vacuum hose and hooked up a hand vacuum pump and applied vacuum and the engine did not stall if the EGR valve is working the endine should stall
Thahk You
Jonathan Baus
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P0171 is obviously for Bank 1 running lean as you know.
I would do a visual inspection of all my vacuum lines as well as any signs of any intake manifold leaks.
If you have access to a scan tool, you can do several tests to see if the o2 sensor voltage changes as well as STFT and LTFT by creating vacuum leaks or by adding fuel via the means of adding propane gas to a vacuum source.
Another method is (this might not suit all people) is to spray carb cleaner or another similar chemical around vacuum hoses and intake gaskets and listen to an increase in engine RPM.
Im going to assume you applied vacuum directly to the EGR valve correct? Did you see or can you see any movement from the EGR diaphram?
Usually with EGR faults they throw codes such as P0401 as an example. Ford also have EVR solenoids too that will control vacuum as needed to the EGR.
Hope this helps.
As dreamer2355 pointed out the code is for a lean condition not the EGR so I’m going to ignore your EGR test for the moment. I would be looking for vacuum leaks first off, here is a video that I did.
http://www.youtube.com/watch?v=9CPqbaSgcok
If you don’t find any you might check fuel pressure and perhaps do a power balance to see if you have one cylinder that is effected which could indicate a possible bad injector. Keep in mind any exhaust leaks before the O2 sensor can cause a lean code as well. Here is a link to a power balance test video.
http://www.youtube.com/watch?v=bAOmUjAjNjE
Good luck.
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