What is the cause of my DTC P0171 - system too lean on Bank 1?

Tiny
GLB2107
  • MEMBER
  • 2001 JEEP GRAND CHEROKEE
  • 65,000 MILES
Hi mine is a 4.0L straight 6 Grand Cherokee. I have had this code for 3 weeks now, since owning the jeep. It is LPG converted, but it runs at the same poor mpg in both petrol and LPG. I've changed the o2 sensor upstream, and checked for vacuum leaks/exhaust leaks and can find none. It runs pretty well, but can hesitate a bit when accelerating ( misfire, though no noise ), is only doing around 10mpg, and performance is terrible. There is a fair amount of black in the end of the exhaust, and actually has a ring of black around the outer edge at the end. I have started to see mentions of the MAP sensor while searching for an answer.
Any help would be greatly appreciated.
Cheers.
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Saturday, September 3rd, 2011 AT 9:59 AM

2 Replies

Tiny
GLB2107
  • MEMBER
Hi
I've read the thread you suggested already, and as I said, I've changed the O2 sensor, it's not running rough, and theres no sign of a vacuum or exhaust leak. And that article doesn't mention anything about an MAP sensor.
Thanks.
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Saturday, September 3rd, 2011 AT 12:03 PM
Tiny
2CEXPT
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Lean fuel condition could be caused by one of the following below: Check it before you comeback with testing results on each-

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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Saturday, September 3rd, 2011 AT 12:28 PM

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