Ford 5.4 code question

[harleypauls]

I have a 1999 Expedition, and the 2 codes I get from it say:
System too lean bank one, and System too lean bank 2. I have done nothing new to it.
I replaced the maf sensor 6 months ago, and I changed the air filter.
Any ideas?
Paul

[76ANTHONY]

What Are The Codes?? I'll Look Um Up

[harleypauls]

I can't remember the numbers, but that is what it said in the book.
I think it was like code 0171 and 0177

[Eliminator 4 Life]

maybe you can find some info at www.fordf150.com

[redi4fun]

What is the truck doing?
Stumbling, bad idle, etc.

[76ANTHONY]

pm your fax number i'll send you the info

[harleypauls]

What is the truck doing?
Stumbling, bad idle, etc.
Rough idle, no real loss of power though.

[76ANTHONY]

check the #1 o2 sensor could be that its running flatline

[harleypauls]

check the #1 o2 sensor could be that its running flatline
Where's the #1 o2 sensor located?

[redi4fun]

Do you have a hard time starting the truck? Does it hold idle by itself, or does it need help?

[harleypauls]

Do you have a hard time starting the truck? Does it hold idle by itself, or does it need help?
Starts fine, idles by itself, just rough, not smooth idle

[blownmirage]

check the pcv hoses, they are real long and the lines separate at the y connection or at the pcv valve itself and can cause that code

[redi4fun]

Check the vacuum line directly behind the throttle body. It tends to dry out and crack over time. Run your hands over all the lines and feel for a leak.
The other thing it could be is the IAC valve. May need to take out and clean or replace. Very easy to do.

[Slacker]

I have a 98 expedition. Mine was runing fine then the check engine light came on and it would run but idle rough. I talked to my mechanic and he said that the early exp. were having problems with the pcv. There is a plastic line that looks like the Letter F and it had cracked. So the computer was trying to compensate for the vacum leak. It only cost about $50 for part and install. Hope this helps
CT

[harleypauls]

The other thing it could be is the IAC valve. May need to take out and clean or replace. Very easy to do.
Where is it at and what is it?

[redi4fun]

Where is it at and what is it?
HP,
I think you are better off checking the vacuum lines. The one slacker is speaking of is the one that was broken in my truck. It is easy to check and even easier to fix. I bet that is the problem.
The IAC probably is not the source of this probem because the truck can hold idle on its own. IAC= Idle air control.

[redi4fun]

HP,
Check this out. http://autorepair.about.com/library/faqs/bl903d.htm
Are you sure the two wires in the MAF are clean. If you have a filter like the K&N the oils from the filter get stuck to the sensor wires and they do not read correctly.
Good Luck

[harleypauls]

I'll try all of you guys suggestions when I get home tonight, and I'll let you know tommorrow what I find.
Thank again to everyone.
Paul

[BowTie Rick]

HP,
Check this out. http://autorepair.about.com/library/faqs/bl903d.htm
Are you sure the two wires in the MAF are clean. If you have a filter like the K&N the oils from the filter get stuck to the sensor wires and they do not read correctly.
Good Luck
Impossible. We have documentation to prove otherwise. We've soaked them in oil overnight and even had them hooked up to an air brush spraying oil onto them. Doesn't phase them a bit. What does mess them up is the oily residue that leaks from the potting material when it begins to break down. We have tested hundreds using signal generators, under the microscope, and chemical analysis of the wires. Guess what, never found one yet damaged by the oil. Its an urban myth. Did you know that MAF have a 20% failure rate irregardless of filter type or vehicle manufacturer?

[redi4fun]

Impossible. We have documentation to prove otherwise. We've soaked them in oil overnight and even had them hooked up to an air brush spraying oil onto them. Doesn't phase them a bit. What does mess them up is the oily residue that leaks from the potting material when it begins to break down. We have tested hundreds using signal generators, under the microscope, and chemical analysis of the wires. Guess what, never found one yet damaged by the oil. Its an urban myth. Did you know that MAF have a 20% failure rate irregardless of filter type or vehicle manufacturer?
I believe you Rick,
I should have been more clear, it is my understanding that if you use too much oil on the filter it will coat the MAF sensor which will in turn collect alot more dirt on the sensor wires. It is then that they begin to give false readings. Over oiling the filter is not the direct cause, it just contributes to the problem, si or no?
It sounded plausable to me. My sensor wires were black with soot and when cleaned the code disappered and never came back. I think it was my fault for putting too much oil on the filter in the first place.

[rmarion]

wealth of information
http://www.ford-trucks.com/

[IMPATIENT 1]

it's the vacuum connector at the back rh corner of your intake.they rot all the time.start it and listen for a loud suckn air sound from that area.i'm pretty sure that is whats goin on. the maf sensor code was a side affect the trucks computer sensed when it first started leaking vacuum.now that's its leaking so bad it switched to a lean code.if your fuel filter and air filter are good, this is what i'd do, starting my diag. at the dealership!

[BowTie Rick]

I believe you Rick,
I should have been more clear, it is my understanding that if you use too much oil on the filter it will coat the MAF sensor which will in turn collect alot more dirt on the sensor wires. It is then that they begin to give false readings. Over oiling the filter is not the direct cause, it just contributes to the problem, si or no?
It sounded plausable to me. My sensor wires were black with soot and when cleaned the code disappered and never came back. I think it was my fault for putting too much oil on the filter in the first place.
Sounds like potting material. The potting material leaks out through the small gap where the wires go into the body. You have to over oil the hell out of it for it to drip off and get on the wires. Even if it did, it should burn off on the clean cycle. When you turn the truck off, the MAF gets red hot to burn off impurities. What we have found out is that the filter oil does burn off but the potting material leaves behind residue. Really sounds like a bad sensor. You said you had it replaced once already. Did they give you new or a reman? I can tell you that blaming the filter will soon go away. We've taken more than a few dealerships to court and are batting 1000 so far :boxingguy For all the crap you hear on the web, I can guarantee you that K&N is the ONLY filter company that does all the testing we do. Others use misleading and inaccurate statements and even publish flawed filtration test results. The diesel forums are the worst. I can find more than a few errors on the supposed independent test (Spicer) that floats around on them. He f'ed it up real bad.

[redi4fun]

Sensor has never been replaced, just cleaned. Thanks for the info Rick.