Hi, I was wondering if anyone could offer me any help in figuring out what the problem actually is. I have an 04 5.4 supercrew with 39,000 miles and the truck runs fine right now. I have already cleaned the MAF (check engine light stayed off for almost 2 weeks) and the light has come back on(cleaned it again and the light came back on the next day), is it possible that it is bad or is it something else? Any help would be appreciated, thanks!

 

The book says if it isn't the MAF, it's a vacuum leak or a clogged fuel filter/low fuel pressure.

 

Or , the drivers side upper intake gasket.

 

Makes sense to me - that sure would cause a vacuum leak.

 

Possible causes, from Ford PC/ED manual
Fuel System.
Fuel pressure regulator (leaking, faulty).
Fuel filter plugged, dirty.
Fuel pump (weak, check valve leaking).
Leaking/contaminated fuel injectors.
Low fuel pressure or running out of fuel.
EVAP canister purge valve leaking (when the canister is clean).
Fuel supply line restricted.
Fuel rail pressure sensor (incorrect reading).
Ethanol content in the fuel
Air Induction System.
Air leaks after the MAF.
Vacuum leaks.
PCV system (leak or valve stuck open)
Improperly seated engine oil dipstick.
Air induction turbulence due to incorrect air filter.
Exhaust System.
Exhaust leaks before or near the HO2Ss (exhaust manifold gasket, mating gaskets)
EGR system.
Vacuum hose disconnected on EGR System Module (ESM) applications
EGR valve tube/gasket leak
EVR solenoid vacuum leak
Secondary Air Injection.
Damaged/malfunctioning secondary air injection system (mechanically stuck valve).
Air Measurement System.
MAF sensor (contaminated, damaged, or faulty)

 

Why is the MAF listed - Is Ford contradicting itself? Scorpio says the same thing.

It can only be the MAF if BOTH banks test positive for lean.

 

The section of the PC/ED covered all these DTC's P0171, P0174, P1130, P1131, P1150, P1151, P2195 OR P2197. It is possible that a MAF can cause just a problem with one bank, but other problems must also exist. MAF is one of the last components to check in this pinpoint test.

 

My PC/ED is just giving me Oasis #'s. Are you connected to Oasis ? Or you just going from a DVD or something?

 

On PTS, under service publications, and then to PC/ED

 

I have an 03 with a 5.4 and about 42K. I haven't had the P0174 problem.

However...............I do have a 2000 Windstar and the 3.8 is notorious for the P0171 & P0174 problem. The fix is to change the Isolator Bolts inside the plenum. After a while the seal on the stock bolts breaksdown and causes air leaks. I changed mine out and it wasn't too much of a hassle. I don't know if the 5.4 has something similar but I figured I'd pass the idea along. Below is the Windstar link talking about it.

John


http://www.automotiveforums.com/vbul...d.php?t=338113

 

I found it here -

-PCED OBDII-A ~ Diagnostic Subroutines-

 

Well, I replaced the fuel filter today so hopefully that'll do it. I'll keep you guys posted to see if that does the trick, thanks for the suggestions.

 

That's a good place to start. Since your replacing the filter, it's a good time to check your fuel pressure @ the rail along with your regulator. I think a cheap guage is about $30 - Auto Zone will rent yuh one cheaper than that.

 

Just out of curiosity, does anyone know why after I cleaned the MAF the first time the check engine light stayed off for two weeks; and when it came on again I cleaned it again and it came on the next day?

 

Well, the check engine light came back on again this morning. I've noticed that every time it comes on it seems to be below 10 degrees; would that have anything to do with what is going on? Also, I went to autozone again to see if the same code came up and it did. Any help would be welcomed, thanks!