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Holton345 06-29-2013 04:25 PM

Ongoing Lean Condition, OBD II
I keep throwing P0171 and P0174 (both the same legend, reading lean and using more fuel than normal, is what it seems to be saying when I read it)

I have a 2003 Sport 4.0L 5 speed.

I have done the following:

Dealership installed all four O2 sensors (don't know brand but am sure that they would only use the OEM stuff and not Bosch).

Dealership installed six new plugs.

I removed the goofy, mismatched cold air intake. It was a mix of the main tube from the throttle body with an AIRAID short tube to a giant, oblong (not conical) K&N filter. This was my temporary solution because of the damage to the old filter that was on there when I bought it about a week ago.

It came with an actual AIRAID filter that was nasty, black with filth, and full of small holes. This filter also threw the same codes as the K&N that I slapped on there the other day.

Yesterday I scored a complete OEM air intake from a 2004 Rubicon. I installed it. I cleared the codes.

It started up with no CEL and ran really roughly for a few minutes. Then it smoothed out a lot and all seemed great.

Then the CEL came back on.


I checked the codes and they are the SAME ONES! ARGH! P0171 and P0174 - lean condition detected.

What else could it be? I do not see any cracks in the manifold. I know that one might be there because of the history of these things. But could it be something else - hopefully much less expensive than another crack-prone manifold?

Will driving lots of hard Interstate miles as my daily driver for commuting with these two codes be a problem or burn something up?

The motor also is running a bit hot, with the needle pegged at about the same place as the oil pressure one - just past straight up by about 1/8" or less. Can this be contributing or related? How do I lower my engine temp? The radiator is full to the top with orange stuff.

Pretty confused, and worried about driving this thing every day until this is sorted.


SeVeReDiStOrTiOn 06-29-2013 06:15 PM

Being that both banks are lean check the fuel pressure.

Temp sounds a little warm, it should be around 210* give or take some depending on hot weather. My needle use to sit right around there but after a flush and new stat 90% of the time it's a needle width below 210*. So flush yours, replace stat and refill with a 50/50 mix HOAT and distilled water.

RevCo666 06-29-2013 06:20 PM

I'd be weary of what exactly the dealership put in for o2's... Making assumptions they they didn't put in bosch isn't exactly fact. Go back and ask them. Bet ya they put in bosch's as they are the most expensive ones out there that are least effective for a jeep.

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