I'll give you some history first, on 4-16-08 I replaced clyinder heads with updated heads,no problems then a short while after that imagine this if you will those crappy cork gaskets started leaking 6.00 a quart oil all over the place so I replaced them with metal rubber gaskets! problem solved. Then not a week later it started throwing this lean bank 1 code, of course you have to take the plenum off to change the valve cover gaskets and yes I replaced those gaskets also with new one's! I have checked for vacume leak's and can not seem to find one ,but all indication lead me back to thinking there is one. when I start it it idle's high and of course I'm getting this lean code! could it be a o2 sensor or does that show a different code???? any help would be appreciated! thanks Alan
you need the specific code, but basically its 49% chance its the manifold gasket, 49% chance it is a dry rotted or burnt vacuum line, and 2% chance its the O2 sensor.
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2001 SuperCrew 4 x 4 5.4 XLT - 190,000 miles
2002 Explorer 4 x 4 4.0 XLT - 120,000 miles
that being said, i did have a bank 2 code on our 2002 that the specific code lead me to believe it was the O2 sensor and not a vacuum line. I pulled the electrical connector and it had a spot of contamination on 1 of the 4 pin terminals. cleaned it and o.k.
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2001 SuperCrew 4 x 4 5.4 XLT - 190,000 miles
2002 Explorer 4 x 4 4.0 XLT - 120,000 miles
Thanks for the response Steve! Well I've check every vacuum line I could find and could not find anything so I guess I'll replace them all if need be (not that many). I'll get the specific code today and let you know! there is one area of concern,there seems to be a heat riser of sorts at the front of the plenum right behind the the throttle body where it goes into the plenum I could not get a factory gasket for it so I found an o ring that fit it, but does not seem to be leaking there no increase in rpm's when I put the propane bottle up to it,also I'll check the connectors
also replaced plenum gaskets when i replaced valve cover gaskets the intake was also new when i replaced heads problem didn't start till valve cover gaskets were replaced!
off hand, i would be looking for a vacuum hose that is swelled, hard, or cracked. i have had problems specifically on those connected to the EGR and high heat areas close to exhaust manifold, or stainless riser tubes.
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2001 SuperCrew 4 x 4 5.4 XLT - 190,000 miles
2002 Explorer 4 x 4 4.0 XLT - 120,000 miles
well sorry it took so long got sick! the code is a po171, I also did some research on line and found a sight that clean the maf which I did and while I was doing that noticed a cracked vacume line repaired that cleared the code and so far no re appearance of the code yet !!!!! Wish me luck
dopey dopey me!!!!!! well after changing the the entire set of gaskets and o-rings on the intake,I was sitting there looking over the job as I normally do to see if I missed anything! and low and behold there was a fitting on the air intake after the maf that was had nothing on it, so I start looking around and the breather to the oil filler was tucked neatly under the other hose's I NEVER TOOK THE DAM THING OFF!!! IT HAD BEEN OFF SINCE I CHANGED THE VALVE COVER GASKETS! nothing like a 1/2'' hole after the maf to make things nice and lean!!!!! thanks for all the advice guys
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