My 02 screw threw PO0171 code AGAIN!! I am FREAKING TIRED of this DAMN code!! Usually I get this code in conjuntion w/ PO0174 but this time it is just the 0171 code showing. I have already replaced the PVC valve w/ MOTORCRAFT, cleaned out the throttle body& EGR valve, replaced the elbow at the PCV valve and some vaccum hoses by the throttle body. The MAF was replaced about 6 mos ago due to one of the filliments being broken and gone completly. I have checked and checked like a million times for any exhaust leaks and I cannot find a SINGLE one! I have had the smoke test done by my Dads mechanic at his work and NO vaccum leaks. My only guess is to replace the EGR valve. I have not changed the 02 sensors as of yet{still have the OE sensors and 163xxx miles}. Many ASE certified mechanics have told me that if an 02 sensor was going bad it would throw a RICH code not a LEAN one.

Any thoughts would be appreciated!!

 

Change the front O2's on general principle.

 

Any thoughts? Alright. - The ASE's you refer to need to get back to class! That isn't true at all.

When their bad, they can show rich & lean on the same bank. Now running rich, that's different. Running rich can smoke the O2's pretty quick.

Check your IAT grommet. That has to be tight, or you'll always thro that code.

 

What is the IAT grommet? Where would it be located?

 

IAT = Intake Air Temperature. Its a temperature sensor on the intake tube. After the filter, before the manifold

 

Review of code 171 is a lean setting of the "PCM fuel software table" for bank 1 (pass side) only.
Do to either a rich conditon on the intake side causing the OX sensors to attempt to correct the issue by shifting the table lean or a very lean intake condition causing the OX sensor to richen injection THEN reverse the reaction back to lean. This is a double reaction that finally settles down to one point.
In this case only one bank is detecting an issue.
Look for an issue with an intake gasket on one runner on bank one cylinders, leaking injector on one cylinder for bank 1 etc.
Anything that only shows up for bank 1.
Any other place common to both banks usually does not set code for only one bank.
Good luck.

 

I agree, that's the last place you look, -"intake gaskets". I say last because that's a good size job in ridding yourself of DTC's. All other possibilities should have been checked first.

Also , the V8's have known gasket problems @ the water jackets (front of intake) AND in the rear on the passenger side. Ford has a special gasket for that, via TSB. The replacement gasket set for your model -

Wait, scratch 1/2 of that, the TSB goes thru the 2000 model years. So, the problem is just at the front jackets, for all 2valve models. That doesn't necessarily mean that's where your gaskets are leaking. It's just common place where those suckers go bad. You'll see what I mean, IF you change them out.

 

Well I recently had a smoke test done to see if the intake gaskets were leaking and they are not. I replaced the IAT sensor last night and had the codes cleared and the SES light stayed off for a while. I changed my oil today{MOTORCRAFT filter, Valvoline Maxx life 5W-20} and I purchased new upstream 02 sensors-{BOSCH} but I was unable to get the old ones off the truck. I have soaked them in liquid wrench for 4 days straight and the pipes were hot when I attempted to replace them today. They would not even budge!! I do my work over at my parents due to my condo associations stupid "no working on vehicles in the parking lot" rule. When I got half way home the SES light came on again!!!! My bet is the old OEM 02 sensors. I just wish I could remove the old ones to replace w/ the new!!!!!!

 

A shop will switch them out for yuh, under $100. Probably charge around $80.

 

everytime Ive seen this code, it was a vacuum leak, maybe your the first legitimate p0171 ever!

 

I wouldn't trust a smoke test for intake gaskets. For the lines, I'd go with a vac tool to test. That will show you for sure. You plug the vac harness ends and apply vac. Those vac tester guns are cheap to buy.
Why ? That has nothing to do with it IMO. It's the grommet that dries out and cracks. You can use Permatex Black fix that or some kind of silicone sealer.

 

So If it is the intake gaskets would they be hard to change? I have done this before when I had a 5.0 stang back in the day. I am not too familar w/ the modular motors and the plastic intakes. I think I could do it I just dont want to break that plastic intake.

I have had the intake boot off the truck and it doesnt have any cracks. still pliable.

 

I had lean codes when my exhaust manifold gaskets went on my 01. I did the same thing as you, until I finally blew out a big chunk of gasket and heard the tell-tale ticking.
My 97 ended up doing the same thing a few months later, and even though I didn't hear the ticking, I went right for the exhaust manifold gaskets and the problem went away.

 

Also, if it turns out to be exhaust gaskets, get the metal gaskets. I found that out the hard way.

 

How hard is it to change exhaust manifold gaskets?