01 explorer 4.0 SOHC P0171 & P0174

[2009KVFD976]

Hello all. my 01 sploder 4L SOHC with 165k is throwing code p0171 and p0174 after i cleaned the spectre air filter. i had it in for about a year and cleaned it out per the directions and it worked fine for about 10mi and cel came on with those codes. ive cleaned maf, did the seafoam spray and did lucas fuel treatment with no change... my fuel mileage went to crap (only getting about 250mi/tank) was getting about 320-340. Any help will be greatly appreciated!!!

 

[2000StreetRod]

oiled filter?

Did you oil the air filter after cleaning it? If so, the oil may have contaminated the MAF sensor element. Try cleaning the MAF sensor again.

 

[swshawaii]

IF you have this PCV elbow, it's almost guaranteed failed @ 165K.
Be sure to check the underside of this common p0171/174 culprit.

http://www.explorerforum.com/forums/showthread.php?t=314670

 

[2009KVFD976]

Thanks for the replies!!
The filter was oiled and the maf was cleaned AFTER recharging and codes still came up.

The pcv lines are different on my engine. all that runs under the intake is the heater lines. it has a rubber hose that goes behind the intake but i cant get my hands back there to find and or replace it. maybe removing the intakes will make it visible...

 

[2009KVFD976]

UPDATE cel is still on after hooking up a smoke machine to a vac line. found the egr diaphragm was leaking really bad so i replaced it and cleared the codes. it came back within 15mi. also i replaced the pcv and intake gaskets. still have 171 & 174!!. When it gets up to around 2500-3000 rpm, there is a slight high pitched whistling like there is a vac leak but i cant hear it under the hood... any ideas r greatly appreciated!

 

[2000StreetRod]

Lean condition procedure

Lean condition procedure

 

[2009KVFD976]

heres what my code reader tells me.
P0171 freeze frame data
STFT B1 7.8%
LTFT B1 25.0%
STFT B2 3.9%
LTFT B2 25.0%
CALC LOAD 75.6%
ENG RPM 2471

Does this narrow anything down?? TX emissions testing is very strict and will not pass a vehicle with a CEL. new EGR valve, upper and lower intake gaskets, PCV valve, IAC valve. fuel press is 52 at idle. it does hesitate a little bit when i first start it in the AM (takes about 3-5 secs until it starts) and whilr trying to pass somebody on the highway, u stomp on it and it takes a bit for it to pick up then it runs like a bat outta hell!! I will continue testing the TPS, MAF, and O2 sensors.

 

[2000StreetRod]

OBDII criteria

According to the 2001 Ford OBD-II System Operation Summary:

Typical fuel monitor malfunction thresholds:
Long Term Fuel Trim correction cell currently being utilized in conjunction with Short Term Fuel Trim:
Lean malfunction: LTFT > 25%, STFT > 5%
Rich malfunction: LTFT < 25%, STFT < 10%

Your left and right bank trims are not that different indicating a cause affecting both banks. Your fuel pressure is low compared to mine which is at least 60 psi for all engine speeds and loads. Has the fuel filter ever been replaced?

 

[2009KVFD976]

According to the 2001 Ford OBD-II System Operation Summary:

Typical fuel monitor malfunction thresholds:
Long Term Fuel Trim correction cell currently being utilized in conjunction with Short Term Fuel Trim:
Lean malfunction: LTFT > 25%, STFT > 5%
Rich malfunction: LTFT < 25%, STFT < 10%

Your left and right bank trims are not that different indicating a cause affecting both banks. Your fuel pressure is low compared to mine which is at least 60 psi for all engine speeds and loads. Has the fuel filter ever been replaced?

Yes. i forgot to mention it in my earlier post. it was done about a month ago.. my MAF is showing infinite resistance while i ohmed it out. il have to do the voltage checks on MAF and TPS.

 

[2009KVFD976]

Im actually leaning towards replacing the FPR or fuel pump. im still trying to find out where the high pitched whistling is coming from when accelerating at about 2500-3000 RPM...

 

[2000StreetRod]

FPR location

The fuel pressure regulator is located in the tank. You could have a weak fuel pump, a defective FPR, or a split fuel line hose in the tank. Ford Explorer Ranger Fuel pressure test procedure.

Since the fuel pump assembly is a pain to remove, I'd try to find the source of the RPM mid-range whistle first.