2004 Ford Focus System too lean, replaced MAF, poor perform

AMITZOHAR

MEMBER
2004 FORD FOCUS
4 CYL
2WD
AUTOMATIC
35,000 MILES

Engine warning light turned on
Trouble code was P0171, system too lean
Garage cleaned MAF sensor & reset trouble code
Trouble code turned on again after a day
I ordered a new MAF sensor from Global automotive FL
After installing new MAF, RPM is very unstable when engine is cold and car barely accelerates
When engine warms up it's OK, still a bit chubby
Light hasn't turned on for 2 days after replacement

3 Replies

RASMATAZ

MECHANIC
75,992 POSTS

Hi AmitZohar, Welcome to 2carpros and TY for the donation

Other contributing factors for a P0171/P074- Lean fuel condition could be caused by one of the following below:

1. Vacuum leaks
2. EGR and PCV valve.
3. Low fuel pressure.
4. Dirty fuel injectors.
5. Mass Air Flow Sensor.
6. Oxygen Sensor.

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Tuesday, October 26th, 2010 AT 4:53 PM

AMITZOHAR

MEMBER
2 POSTS

OK, but after than I replaced the MAF sensor and things got worse. Is the new MAF sensor bad? Does it point to another problem?
Regards

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Wednesday, October 27th, 2010 AT 3:12 AM

PUFFNSTUFF

MEMBER
59 POSTS

Hi,

Same thing happened to me. Turned out it was the pcv hose where it goes into the intake at the rear of the engine. Small angle hose which ford charges $50.00 for. Got mine at a scrape yard for 5 bucks.

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Thursday, November 4th, 2010 AT 7:55 AM