mickeye5

My "service engine light" has been on since mid December and the codes are 171 & 174 telling me it's running lean. I have 2000 L 73000 miles. I replaced all the sensors (MAF all O2's) new fuel filter, went through all vac lines Erased the codes properly 20 times. And I am at a dead end. Light just came back and codes are still the same. Any idea what is causing the lean codes?
Please help me with any suggestions if you can. Thanks much........Mike

Pete187Rock

Im sort of in the same boat, I got a P0171 that is kicking my ***. Havent went on a blanket fix party yet but havent found any vac leaks though I think I hear one.

bgstew6

check the Vac line that comes off the PCV (passenger side) T. The one hose that goes back behind the motor and to a connection on the back lower side of the lower intake manifold. ITs a bear to get to with the SC on the truck unless you have girly hands......

OVer time the rubber 90, deteriorates and gets mushy and splits from oil that puddles in the lower intake manifold (caused from oil that gets sucked out of the crank case via the PCV system) been the cause of that lean code, for many, after they have checked all other vacuum connections and post maf connections on their truck and those checked out good.

Baring a tune issue this may be the most likely culprit

Pete187Rock

Yeah all the obvious ones Ive checked, including the PVC hose and its all good. That may be the culprit is the one I cant see and like I said I can hear a hissing coming from teh back side and when I listen with a scope I can hear it but cant pinpoint it. So you say its on the backside of the lower intake? Can you actually see it? And no I have big manly gorilla hands. lol Thanks for your input ill go see if I can locate that 90 real fast. brb

I just went and looked but cant get my meat hooks back there to inspect it yet. guess ill have to take some stuff loose since I dont have a mirror over here. Also what do you mean a tune issue? I just did the tune up at 70k just because i had bought the truck and just went ahead and did it since I worked at Ford. Its got 88k on it now.

Pete187Rock

Quick question though, if it had collapsed wouldnt the engine idle funny? Like I said earlier the truck runs strong, not a skip in it.

bgstew6

No you cant see it...I got Ape Mits Too LOL....

Direclty in center, lowest portion, rear of the lower intake manifold. The PVC line that comes off the passenger side Valve cover comes up to a t. One line goes up to the upper plenum. The other goes back to the connection we are talking about.

In the attached pic the connection is circled in red...although you cant see it....there is a barbed connector back there with a rubbrer 90 degree elbow on it......

Depends..on how bad the leak is....

I understand what you re saying though......typically post MAF (unmetered air) leaks trip a lean bank one and two code not jsut a single

also if it were an 02 sensor acting up that an accompanying 02 sensor code would be present as well

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Pete187Rock

Hmmm, I see the hose going back there but ill probably have to take the blower off just to inspect it. I tried to spray some starting fluid back there but no luck getting a response. Guess I know what im gonna be doing tommorrow evening lol. I bet thats it too because I can hear a hissing noise coming from behind the blower but can get a bead on it. Looks like I pretty much have to take the blower off just to get my meat hooks on it huh?


Also the truck is completely OEM from what I can tell.

bgstew6

Pretty mcuh my friend...I have to....I can barely touch the 90 with the tips of my fingers...no way to get it off or on for me unless I took the blower off.

LIke I said before...I would be surprised that it did not throw both lean bank codes as typically all post maf leaks trip a code for each bank.

but hey at least you will have the blower off so that you can clean your IC....if it has not been done....then get y ourself an oil Sep to keep from ever having to clean the IC again.

Pete187Rock

Ive cleaned the throttle body good before I did teh tune up on it. Whats this oil seperator you speak of and how much is it?
The blower doesnt look to bad to get off, just looks like its heavy as hell. Should the gasket be ok if im careful taking it off or should I get another one?

bgstew6

blower is simple...IMO

Do a search on Oil Seperator....it will go inline on PCV lines....between the T on the passenger side and the Plenum....scrubs the vapors as they are evacuated form the Crankcase before heading into the plenum....Typical of all Ford SC applications...over time the vapors (heavy laden with OIl) will collect oon the IC (undre the SC) and cake it up....affecting performance as not allowing the air to flow smoothly and freely thorough the IC fins. The oil sep will keep the heavy oil particulates from entering the intake tract and cloggin up the IC.

SC Gaskets (there are two) one between SC and Midplate and one between midplate and lower intake manifold. THey are both metal and reuseable. DO a search on SC removal or IC CLean How to....check the How to section as well. WIll have all the info ya need, tools, tq specs, tq sequences and cleaning tricks tips hints. May take ya bout 3 hours to remove SC, clean IC, check that hose, and then put it all back together....while the SC is off is a good time to change plugs....defintely makes it easier while it is off.

GOt any other mods? IF stock boost....NGK TR6 plugs or Motorcraft replacements gapped to .040.

Pete187Rock

Cool, Ill look into that and Ive already replaced the plugs with motorcraft plats and Im sure I gapped them at the lowest of teh OEM gap range whatever that was. As far as I know its pretty much stock though my buddy John had a 01 Lightning with a programmer on it and pulleys and he drove mine and said it pulled just as hard so who knows. It looks stock to me though. Wonder where I can pick up a 90 to replace the one on there on a Sunday lol. May have to wait on my next off day to knock it out. I just hope that damn 90 is fudged up after going through all the trouble of getting to it. lol

Thanks for the advice though, I wouldve never known it was back there if you hadnt of told me. lol Good lookin out.

bgstew6

90 should not be hard to find....autozone, pep boys etc ....not fancy to the ruber elbow....

NP man....me to.....

Pete187Rock

I know, Ive used spark plug boot ends to replace them at times because the local parts house dont ever have a 90. lol Now if I an just figure out whats wrong with my brakes and figure out the loud bang noise i get when i crank my truck up with the a/c on ill be good to go., lol I think its the fan clutch. as far as the brakes im not sure,

Pete187Rock

lol I just noticed this was in anotehr check engine thread, not the one I originally started. lol I guess it was a good threadjack since it pertained to the same issue the thread was started on. lol

bgstew6

whats wrong with brakes??