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ODB2 Codes: P0174 & P171 ('00 V6 Duratec)

D

Don

CEG'er
Joined
Oct 12, 2007
Messages
33
I'm getting two codes both are system lean codes, one for bank 1 and the other for bank 2. The car has 144K miles on it and I haven't changed the plugs on it yet. I have changed the TPS, IAC, and MAF sensors within the past month but the car still can't idle. The issue gets worse when the temps drop...it's okay in the 30's but once it gets into the single digits the car doesn't want to idle and dies. Is the issue a bad sensor? Any ideas.
 
I bought the car with 54K on it, and I haven't changed the O2 sensors yet on it...so worse case there's 144K on the O2 sensors.
 
Today I went ahead and replaced both o2 sensors and replaced the PCV valve since they have never been changed for as long as I owned the car. The car idle better but then started to do its thing again. I'm sick of this car and I think I'm going to take it in and have someone else look at it...unless there is someone out there has any other ideas? By the way the codes popped back up again.
 
Don said:
Today I went ahead and replaced both o2 sensors and replaced the PCV valve since they have never been changed for as long as I owned the car. The car idle better but then started to do its thing again. I'm sick of this car and I think I'm going to take it in and have someone else look at it...unless there is someone out there has any other ideas? By the way the codes popped back up again.
Click to expand...
you have an air leak after the MAF. check all your vacuum lines and all the connections on the intake.
 
I'll check one more time for a vaccum leak. I'll let you know what I ended up doing.
 
Well I took the car to the dealership since another mechanic wouldn't touch it and I didn't want to mess around with it anymore. Based on what the Ford Dealership said and diagnostics, the issue is a result of bad intake gaskets...now this is there "best estimate". The cost would have ran me $566.00, but since I can wait I decided to hold off since that's way more than I wanted to spend. There best estimate was based on spraying in the intake an noticing a "whistle" change.
 
I read the link you posted and it makes me think I can do this myself....so you don't need to pull the engine out to get at the Lower or Upper Intake Manifold gaskets? I have a Haynes manual and they showed them taking the engine out.
 
No, you don't pull out the engine to clean the UIM/LIM.

Haynes had the engine out because they were also showing how to remove the engine.
 
I have been having the same problem, and hadn't tried checking the intake manifold for leaks. A can of carb cleaner in hand, I headed out last night after reading this thread, and wah-lah! What seems to be a fairly large leak on the gasket between upper and lower plenums on the passenger side end of the motor. Tightening the bolts on the UIM even seemed to make it worse.

I've got the CEG forum UIM/LIM instructions all printed out, and it seems like a reasonably straightforward job (diagrams and pictures are worth gold at this point). Maybe I can kiss the P0171/0174 blues goodby.
 
Spikedog said:
I've got the CEG forum UIM/LIM instructions all printed out, and it seems like a reasonably straightforward job (diagrams and pictures are worth gold at this point). Maybe I can kiss the P0171/0174 blues goodby.
Click to expand...

Before you start the teardown have all the parts you need in front of you. Another CEGer writes that parts are becoming scarce for early model (i.e. 96/97) Contiques. This member had a hard time finding the fuel rail seals and fuel injector O-rings. He did finally get them via Bill Jenkins, but only after his local stealership said some parts he wanted were obsoleted by FMC. If you remove the LIM & UIM you need to have all parts described in the How-To except the O-rings. But since you've got everything apart carefully removing the injector and installing O-rings would be a good idea.

Also you want to have the correct torque wrench for the inch pounds torque spec you should adhere to. Everything is aluminum so don't over torque. Another thing definitely replace the PCV valve and use hose clamps on each hose location. This will also help the P0171 & P0174 from returning. Remember you're trying to stop unmetered (i.e. not measured by the MAF) from entering the engine. So inspect all hoses - the big rubber ones and the tiny plastic vacuum hoses - for cracks and install new gaskets everywhere. Don't skimp and re use the IAC, throttle body, EGR or any other gasket you've exposed during the intake rebuild.

One last thing after you've cleaned the LIM with Berryman B-12 chemical parts cleaner put a little oil on the secondary linkage. After putting everthing back together I found my LIM linkage was so stiff the IMRC couldn't open the secondaries. Luckily I was able to loosen it up with it still in the car.

yapper
 
I just read the thread with the o-ring unavailability issue. I was planning on just the upper intake gasket switchero, leaving the lower intake untouched. I didn't have any indication of LIM problem - the UIM leak seemed very large and obvious.

:cool:
 
I know shops have told ppl bad UIM/LIM gaskets and raped them. Had this happen to my brother. He had to have it done and I couldn't look at the car. Issue croped up again and I got a chance to look. Ended up one if the little rubber tubes to the PCV. A $.05 friggin piece. Crappy mechanics! Look at the small stuff first. Really aren't many vac tubes on the Duratec.
 
Spikedog said:
I just read the thread with the o-ring unavailability issue. I was planning on just the upper intake gasket switchero, leaving the lower intake untouched. I didn't have any indication of LIM problem - the UIM leak seemed very large and obvious.

:cool:
Click to expand...

You have to do both. Removing the upper can disturb the lower if the engine has many many miles on it.
 
todras said:
You have to do both. Removing the upper can disturb the lower if the engine has many many miles on it.
Click to expand...

UPDATE: I did just the Upper manifold gasket. The sealing surfaces and old gasket didn't look too bad, and I didn't mess with the LIM. I've got two tanks of gas through the Mystique without any CELs. It idles great, even in extreme cold, and has good throttle responce again. I sure hope that was the problem. Only gripe is the mpg is down around 20-21, rather than 24-25 like it used to get (advantage of running lean maybe :shrug: ).
 
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