I am getting two codes P0171 & P0174 and they only came up at low idle speeds. I drove 100mi and at a traffic light it came up. I reset the codes and drove another 100mi and in the driveway it came up again. The average highway speeds were around 65mph + or – a few. I will be checking it but wanted to see if I can get a little input. I will be checking t he fuel filter, clean MAFS & air leak MAFS to cylinder head.

 

shame on you Gus, I can remember alot. But not the engine in your S.
V8 or 6????

 

3.0 - 6 Sorry!

 

It's in his signature

Gus - you want an OBD tool (such as elm327 - about $25 ebay) that can read the sensors (it'll do codes if it can do sensors) in real time, then start with:
1. don't clear the codes!! you 're losing valuable data and it'll make diagnosis harder
2. the "monitors" - those Supported should all be Complete, if not either you've cleared the codes too recently or you now have a fault that's blocking the uncompleted monitors (and if you're unlucky you'll get no codes to help with diagnosis & fixing)
3. look at fuel trims - per bank there are 2 kinds, STFT (short term) and LTFT (long term)
watch them for a while at idle with engine warm, look for a pattern and post about the values please
4. look at the O2 sensors per bank you have an upstream (of the cat) and downstream
on your era car the O2s are all of the same type
that type (should) switch rapidly from one voltage around 0.2V to another around 0.8V
the upstream should switch often - you may need to rev at idle so enough exhaust is flowing to keep them HOT (need to be 600C or some such)
the downstream voltage switching rates should NOT look like the upstream
watch them (all 4) and have a go at describing how they're behaving

If the varous trims and behaviours are symmetrical bank-to-bank you likely have a vacuum leak somewhere prior to the banks separating.

Actually, it'll probably be the PCV elbow or the like but let's be scientific if you're willing

 

THAT WASNT IN HIS SIG LAST NIGHT CAUSE I LOOKED
ON THE V6, THE BIG LEAKERS ARE STILL LIKE THE xTYPE. IMT ORINGS. ALSO THE SMALL BREATHER ELBOW IN THE BACK OF THE ENGINE. IF IT TOTALLY SMOOTH IT FIRST GEN STYLE, THE REPLACEMENTS HAVE 2 BIG RIBS AROUND THE 90. THE BIGGER LEAKER IS THE LARGE OIL BREATHER ELBOW UNDER THE INTAKE. TO DIAG SPRAY YOU FAVORITE VACUUM LEAK CHECKER MATERIAL WHILE THE ENGINE IS IDLING. SPRAY DOWN PAST INJECTORS AND MANIFOLD IN THE AREA OF CYLINDERS 5, 6. THE BREATHER ELBOW IS DOWN UNDER THE INTAKE AND BETWEEN THE HEADS IN THIS AREA. IF IT STUMBLES, THERES YOUR SIGN
YOU CAN BE SCIENTIFIC, BUT THEN THIS IS A WHOLE 30 SECOND CHECK , IF ITS A SMALL LEAK AND NO STUMBLE YOU WILL HAVE TO MONITOR SHORT TERM FUEL TRIMS AND REPEAT.
BUT THIS IS ALL THE DOWN AND DIRTY LEAN ENGINE FAULTS MOST COMMON ON THAT CAR,
ALSO ON THAT YEAR THE INTAKE GASKETS UPPER AND LOWER SUCK BADLY(PUN INTENDED) THEY CANNOT BE REUSED, YOU END UP WITH LEAKS FROM THEM WAY TO OFTEN. THE LATER YEARS OF V6'S USE LARGE YELLOW AND GREEN UPPER/LOWER INTAKE SEALS THAT ARE REUSEABLE.

 

Well I now have a starting point and will begin checking this weekend and will let you know what I find. The car is new to me and have not had a chance to check everything out. As for OBD reader I have one just did not hook it up I guess it is time to do so. And Brutal you are correct I did not have the engine in my signature but I do now. Thanks for the input!

 

I got all the parts and was ready to jump in but the rain put a little damper on it. Hope to begin in the morning.

 

Gus you might search for IMT repair. There have been several very good write ups with pictures and all the in's and out's of the V-6 problems. It does seem that all the V-6 cars will suffer from these vacuum leaks sooner or later. I would follow Brutals suggestion and replace the vacuum elbow and the IMT o-rings and the intake manifold gaskets. You might also consider the age of your coils because to change them on one side of the V-6 requires the removal of the intake anyway.
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Just finished and all went well I did replace the plugs and coils.

 

Nice rescue info. for Gus guys (don't say this 3x times fast). I had an 02 X-Type 3.0 and it suffered from leaking IMT o-rings. The idle rose and ya heard a sucking noise.

 

Brutal you were dead on! I replaced the elbow and got it all together and at the present time it is running great, no extra parts. I will try to make a procedure when I get time. Thanks for your help!

 

Wow Gus, took you a day to do all this!!! Took me a lot longer, but was not in a big hurry. Glad to hear it all worked out.

 

I have been driving it today and I think I did OK, it seems to be running better. I started the job around 10am and finished around 3:30pm, I also had to get the elbow in that time. I would like to take all the credit but Brutal provided details that made the job go quickly. Thank You Brutal! I hope to have a detailed procedure in a few days.

 

youre welcome Gus, glad to help

 

Just posted my procedure for the elbow replacement http://www.gusglikas.com/AutoRepair2...VacuumLeak.htm

 

Gus - Excellent details and photos. I hope they get FAQ'd.

 

Gus, that is a great breakdown of how to change the parts. I wanted to do something very similar with some of the pics I was putting on site while doing the job but then had some family issues and just did not have the time.
I also was thinking about leaving that last part off because it is a real mess to get it back on but I put it back. I just wanted to point out and hopefully Brutal will chime in, that this left out part he said protects the gas line or something from causing an issue if having an accident and I think showed some pics of what could happen. Might want to check with him to confirm.

 

added to s-type FAQ gus, great job. I still have a few to add of yours in the xk8 thread

 

can anybody please confirm if a 2006 v6 has the same pcv elbow? i changed the IMT orings to green ones already and still get codes p171 & p174.

i bought the breather elbow part from lincoln already but when i got to between the 5&6 cylinders i can not find a pcv valve there and was instead covered with a blank metal plate...

my s-type is currently apart right now hoping for somebody to point me the way...