P0171 and P0174 codes.

[wodywo]

my 2000 explorer 4.0 ohv runs fine for about first 30 min of drive. (smooth idle about 750rpm and no hesitation under acceleration) after this time it developes a rough idle and stumbles through acceleration but once up to speed still runs fine. the only codes it pulls is po171 and po174 bank 1 and 2 lean. i tested and cleaned the maf its fine. i tested the o2 sensors theyre also fine. i cant seem to find any vacuum leaks either any thoughts would be most appreciated

 

[Oxygen]

most likely it is your upper intake manifold gaskets.. very common problem, had the same codes/problem on my 00 OHV XLS too..

 

[Dave A.]

po171 & po174

I have a 1996 E. Bauer Explorer with a 4.0 auto.
A few months ago, I replaced the fuel pump and
regulator. It has been running great. now the idle
isn't consistant. I scanned it and it's both the po171
and po174 sensors. Could these both gone bad at the
same time or maybe intake gaskets. Any suggestions?

Thanks, Dave

 

[BrooklynBay]

Welcome to this forum! I've moved your thread into the EEC-V section. The intake manifold gaskets usually create these codes if they are leaking. Spray intake cleaner onto them while the engine is running to see if the idle changes.

 

[Dave A.]

Cleaned and oiled the K&N air filter

Thanks, BrooklynBay

To my amazement, I took apart the K&N air filter. I cleaned it, even though it didn't look bad, then put the K&N oil on it. The idle was smooth, I scanned it then erased the codes. It's been a few days and its running great!!!


The air filter didn't look dirty, It appears that was the problem. I thought it was the intake gaskets, but new oil on the filter did the trick.

 

[BrooklynBay]

Thanks for the update! The oil from those filters could interfere with the MAF sensor.

 

[wodywo]

update

so at the urging of most of the posts ive seen regarding the p0171 and p0174 codes i replaced my upper intake o-rings then reset the codes wouldnt you know it the check engine light comes on 2 days later with the same codes. any other suggestions out there?

 

[fasteddie460]

Me Too..

I'm getting these same codes, P0174 / P0171. Engine at operating temp. Stumbles through accelaration. I'm thinking a fuel injector is bad.Like its not flowing enough fuel.