P0171 on a 5.0L? | Ford Explorer Forums

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P0171 on a 5.0L?

geosnooker2000

Well-Known Member
Joined
March 29, 2007
Messages
298
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City, State
Somerville TN
Year, Model & Trim Level
'10 Eddie Bauer V8 4x4
So, thanks to all the help here, I got my front diff swapped and new front axles installed. Drives great and is quiet again, so that was the problem. But now...

I went in to autozone to get that stupid CEL checked out to see why it still thought I had a cyl.#8 misfire when I changed the plugs and wires about 2 weeks ago and it solved my rough/weak engine. But that's not what it says now... it says P0171. (fuel system too lean - cylinder bank 1). It does NOT throw the accompanying P0174 that I see so much talk about, just the P0171.

AutoZone jumps to the conclusion that I need a new intake manifold gasket. I'm not going there just yet before I check it out with my bros here first!

First off, here is what has happened lately, in case any of this is pertinent.

1) First code 3 weeks ago was a P0308
2) changed plugs and wires
3) ran great again, but soon started (see unholy roar thread) roaring.
4) took it to my Indy shop guy to see if he could diagnose - he said get it to a muffler shop ASAP because I needed new Cats (4 of them)
5) did that ($1092 ... woo hoo...) and then "roared" my way home to change do the front end diff and axles myself ($)
6) finished that this morning, and took it to AutoZone thinking it was gonna be the P0308 again, but no.

Now, from what I understand, this could be from a vacuum leak - which brings up a question I had while changing out my front diff. The tube that goes out of the top of the diff, is that supposed to be connected to anything (Like, is that a vacuum hose)? Because my original one was not. it came down with the pumpkin, and I thought "oh crap! I forgot to disconnect that before I lowered the pumpkin!) But then I noticed it has a plastic cap in the end of it and while it is completely covered in dirt and grease buildup, it looks like the cap is solid. Of course, that makes no sense. Why would Ford put a hose coming out of the pumpkin that leads to nowhere? But point being, if it WAS hooked up to something, it was doing no good for many many thousands of miles.

Anyway, dirty air filter, dirty MAS (231k miles on this truck), any other simpler ideas before I start tearing the top of the engine off?
 



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Loose spark plug or clogged injector. Intake gaskets on 5.0's really don't have problems with leaking unless they were damaged when installed.

Bad injectors can make or break a smog test. You can buy remanufactured injectors on ebay for $100-$120 and will definitely help if yours haven't been replaced for 231,000 miles but I'd make sure your spark plug didn't come loose first.

If you had a P0174 with the P0171, then i'd look for bad vacuum lines or failing fuel pump.

Thats sucks you had to spend that much to put new cats on a high mileage rig. I'm in MI were there is no smog tests and have never bought a catalytic converter for any car in my life. I've hacked many off though.
 






Loose spark plug or clogged injector. Intake gaskets on 5.0's really don't have problems with leaking unless they were damaged when installed.

Bad injectors can make or break a smog test. You can buy remanufactured injectors on ebay for $100-$120 and will definitely help if yours haven't been replaced for 231,000 miles but I'd make sure your spark plug didn't come loose first.

If you had a P0174 with the P0171, then i'd look for bad vacuum lines or failing fuel pump.

Thats sucks you had to spend that much to put new cats on a high mileage rig. I'm in MI were there is no smog tests and have never bought a catalytic converter for any car in my life. I've hacked many off though.

Oh we don't have smog tests in TN either, but believe me, my eyes were watering just driving down the road. It was unbearable. HAD to be done.

Could I maybe start out with some fuel injector cleaner?
 












diff tube doesnt hook to anything. just kinda lays there. intake gaskets, as mentioned rarely go bad unless you have had a monstrous intake backfire. and i mean monstrous. you can also try some seafoam mixed into your gas. it may help.
 






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