Power Loss at Higher RPM's

coxm1 · 04-29-2010, 03:11 PM

Well, a month or so back my SES light came on while driving over a pass on a road trip. After scanning the car, the code that pulled was “P0171 – Bank 1 too lean”. So I replaced both pre-cat 02 sensors and reset the SES light. However, a week later the SES light came back on, with the same code.

Now, even when I reset the SES light, I seem to have lost horsepower at higher RPM’s. You can feel a noticeable decrease in acceleration at 4,500RPM.

My next guess is fuel filter, however if the filter was getting plugged then I would think that it would say both banks are running lean. Same goes for a vacuum leak. Does anybody have any ideas as to what would cause this code and/or check engine code?

Mike666 · 04-29-2010, 03:18 PM

You might want to check your MAF sensor. Just a thought.

coxm1 · 04-29-2010, 03:21 PM

Quote:

Originally Posted by Mike666

You might want to check your MAF sensor. Just a thought.

I did pull the MAF Sensor out and sprayed it with a specifically designed cleaner but it didn't help.

Andy2108 · 04-29-2010, 03:33 PM

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04-29-2010, 03:11 PM	#1
coxm1 Registered User Join Date: May 2009 Location: Issaquah, WA Posts: 7 My Ride: 2001 325i View My Garage	Power Loss at Higher RPM's Well, a month or so back my SES light came on while driving over a pass on a road trip. After scanning the car, the code that pulled was “P0171 – Bank 1 too lean”. So I replaced both pre-cat 02 sensors and reset the SES light. However, a week later the SES light came back on, with the same code. Now, even when I reset the SES light, I seem to have lost horsepower at higher RPM’s. You can feel a noticeable decrease in acceleration at 4,500RPM. My next guess is fuel filter, however if the filter was getting plugged then I would think that it would say both banks are running lean. Same goes for a vacuum leak. Does anybody have any ideas as to what would cause this code and/or check engine code?

04-29-2010, 03:33 PM	#4
Andy2108 Registered User Join Date: Nov 2009 Location: U.S.A. Posts: 7,814 My Ride: E46M3E92M3'67Cobra View My Garage	vanos seals <--- search __________________ De gustibus non est disputandum.

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04-29-2010, 03:18 PM	#2
Mike666 Registered User Join Date: Nov 2007 Location: MA Posts: 19 My Ride: 2000 323i View My Garage	You might want to check your MAF sensor. Just a thought.