Help, trouble codes P0171, P0174, and P0133

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PennSt8_nuc

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Got a check engine light last week and popped codes P0171, P0174, and P0133. Erased them twice and they cam eback so it wasn't a hickup. I believe 0171 and 0133 are pending and 0174 lit the lamp. The car may be a little down on power but seems to run fine otherwise. No idle problems and cruises at 70 without any issues. I pulled the MAF last night and it looks very clean, no tears downstream, and no split vacuum lines that I can see. Where do I go from here before I bite the bullet and take it to the dealer? Is it possible that its as simple as bad O2 sensors? I would appreciate any help I can get!
 
Believe it or not, there was more than one configuration of the LS produced. What year LS do you have?
Do you have the V6 or the V8?
It makes a difference. For example, if you have a V6, then the first place to look would be the PCV valve and hose elbow.
 
Sorry bout that, I thought I had updated my profile with that info. It is a 2001 LS V6 auto with about 107,000 miles.
 
I will check that tonight. If I do end up taking off the intake manifold to get to the PCV hose can anyone tell me the torque spec or procedure for re-installing them. I don't have a manual.
 
PennSt8_nuc said:
I will check that tonight. If I do end up taking off the intake manifold to get to the PCV hose can anyone tell me the torque spec or procedure for re-installing them. I don't have a manual.
Click to expand...

I have gen II specs only. I'm sure someone else has the gen I specs.
 
Great, thanks for your help. I checked the recorded data on my scanner and it looks like the code popped at idle (780rpm), still an indication of PCV leak? Also, is there any way to determine if it were the MAF? I hear Ford has had some troubles with them. Thanks again!
 
PennSt8_nuc said:
Great, thanks for your help. I checked the recorded data on my scanner and it looks like the code popped at idle (780rpm), still an indication of PCV leak? Also, is there any way to determine if it were the MAF? I hear Ford has had some troubles with them. Thanks again!
Click to expand...

Yes.
No simple way that I know of. PCV hose/elbow problems (V6 only) are more common than MAF problems, unless you have aftermarket intake.
 
i have the 01 V6

yes its the pcv valve hose or long hose that attaches to the back of the throttle body. Usually the hose splits at the back of the engine. Follow the hose from the throttle body to the rear of the engine, it is hard plastic with long rubber boots on each end. The rubber boots split.......If this is ok, then the PCV hose under the manifold needs replacing along with the PCV valve. NOW as long as you're taking off the manifold you might as well change all the gaskets too, and the valve cover gaskets, coils and plugs if you need them. I've done this twice now......its a full days job, better to take it apart before dark then finish in the morning when rested. When you take out the manifold bolts, lay them out in the same order, same with the valve cover bolts, they are different lengths. Also no need to disconnect the throttle wiring. Just remove the bolts holding the throttle and move it out of the way. you should be able to find the diagrams on torque on this site under PCV replacement V6
 
Thanks tireman, any idea on how much torque they need when going back in (intake bolts)? Will I definately need to replace the PCV valve if the elbow is cracked under the manifold or is this one of those while your in there things? Are the intake manifold gaskets rubber? Thanks.
 
yes

Yes, while your in there replace both the elbow and PCV valve. I got the Felpro gaskets, all from rockauto, nice, ordered everything from them, makes it easy and cheap. check the technical articles for torque settings. I've got to run out, maybe I can look them up tonight. one more thing, don't disconnect the fuel rail, gently move it aside to replace the pcv and hose.
 
89 ft lbs

manifold bolt torque 89 ft lbs

sequence

3 7
1 5
6 2
8 4

front of engine
 
Great. So I am assuming that is for the lower manifold bolting to the block. What about the upper plenum to the lower manifold? I checked out RockAuto for the parts and was hoping you (or anyone) could confirm the one part number for me. Is the little PCV valve elbow under the manifold that typically causes the problem Motorcraft part # KCV245 ($12.51)? I was under the impression that this part could only come from the dealer but would be ahppy to be wrong. Last, before I tear apart the intake, I want to be pretty sure this is what the problem it. I have been told to spray some carb or brake cleaner back in around the back of the intake manifold and see if the rpms jump. Where is the best place to spray this stuff so I dont have to soak my engine with it. Any other/better way to test? Thanks again for the help.
 
ok, here goes

do this first, look at the throttle body, there are several lines connected to it from the rear, the one with the big boot is a vacuum line, follow it to the back of the engine towards the drivers side where you will find another boot at the end, go ahead and gently pull the boots and plastic vacuum line off, inspect the boots carefully, the rear one is the problem. If there are no cracks or splits put it back on, then start car, let warm up,,,,,now, pull off the boot at the throttle body,,,if there is no change in the engine performance then the pcv elbow is cracked and leaking. If you have never changed the PCV elbow and PCV valve then it's time. the rubber elbow from the dealer is $25! Its just about a four inch long rubber elbow that's all! Heat kills rubber, why they would use this I don't know, a solid metal elbow would be much better. I understand this design was changed in later models. the valve cover bolts are 89 ft lbs too. The job is not difficult, just time consuming, keep track of every nut and screw!
 
My manual calls out 89 inch/pounds for the intake manifold, not 89 ft/lbs
Chris
 
89 in-lbs does seem more resonable. Are there any autoparts stores that carry repair manuals for the LS, I have never found one.

tireman, the car is idling fine now, should I expect it to get rough when I pull the vacuum hose off of the throttle body if the PCV is OK? If the PCV elbow was currently cracked and leaking shouldn't I have a rough idle now too or is the computer compensating enough for this leak if it has been there a while?
 
me bad!

wrong on me! the torque is 89 lb in!!!!!!!! hey man, look in the technical articles, there are two on the manifold removal w/specs on the V6. Look it up!!!! All the answers are there for you. to loosen up the fuel rail, there is a bracket on the front of the engine, just take the nut off and you can move the fuel rail around. Also you don't need to disconnect the throttle cables, you will see.
if you remove the boot while the engine is running you should get a noticeable change, you you get no change then the pcv elbow is sucking air already and removing the boot from the throttle body should have no effect. However! you may just have a small opening on the elbow. Hey, be sure and check the vacuum line that connects from the middle of the intake air tube. It goes into a "T" connector on top of the engine and goes to each valve cover. This line also rots out over the years.
The car will start to run very rough as the air leak gets bigger. I basically ignored mine until the engine started stalling out.
 
More Confused!

OK, so I took the car home for lunch. I had reset my codes yesterday at lunch time and been driving around with my scanner plugged in to record when I got a code. Well on the way home I did get a code but it was the P0133 again with no other codes (even pending). With the car warm and idling I pulled the vacuum line with the boot on the back of the throttle body (only one with a straight boot) and the engine stalled! Any ideas? Could a bad 1/1 O2 sensor be causing my problems? I would think not.
 
PennSt8_nuc said:
OK, so I took the car home for lunch. I had reset my codes yesterday at lunch time and been driving around with my scanner plugged in to record when I got a code. Well on the way home I did get a code but it was the P0133 again with no other codes (even pending). With the car warm and idling I pulled the vacuum line with the boot on the back of the throttle body (only one with a straight boot) and the engine stalled! Any ideas? Could a bad 1/1 O2 sensor be causing my problems? I would think not.
Click to expand...

I don't think that it could be all of your issues, but I am not certain that it is not. I suppose you could change it for a new one and see.
I don't think that the hose pull test was enough to prove that you don't have any problems with the PCV system.
 
I have an O2 sensor at the house and will try swapping that in tomorrow morning. The 1/1 O2 sensor should be closest to the engine on the passengers side right? Any other ideas on testing. I will try to monitor the fuel trims to confirm that it is a vacuum problem (even if not the PCV elbow). Thanks again for all the help!
 
I had these same codes FOR A LONG TIME, tried to replace many parts.
The plenum is gunked up, needs to be cleaned out.

I had exactly the same codes, replaced half the EGR system, tried a lot of :q:q:q:q...eventually brought it to a mechanic to have other stuff done and he cleaned it out.
Good luck
 
I would think that gunk in the plenum would just result in reduced power or even a rich condition.
 
Fuel?

What about fuel? Is there any way to check for enough fuel (pressure guage or scan tool)? It may be worth throwing on a $11 fuel filter before getting into the intake. Anyone know what the fuel pressure should be? Just trying to rule things out here. Thanks again.
 
interesting

Hmmmmmm, I got the same codes and it was the elbow 1st time, 2nd time it was the boot at the rear that split open. As Joegr says the pulling off the boot is not a definite indicator. My V6 generally ran pretty well until the holes in the rubber got too big. Then it started to stall out and it was necessary to replace the parts.
 
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