Ok here's the break down, wife calls says I have a check engine light so I say I will check it tonight when I get home.
Checked codes got P0171 & P0174 (lean both banks)

Now we just bought this car and I wasnt really expecting this and I have only opened the hood once so I am not too familiar with the layout.
I have read about 9 different posts and I have a few questions.

Now this infamous elbow fitting is this pre 05? do I have this on a 07? And what would be the correct order to diagnose this issue.
I read the vac hose colored diagram (very cool BTW) so im set on that. The intake gaskets dont look to tricky I think I can manage that no problem.

I have come across these codes before on my Explorer and it took a complete replacement of all the upper intake gaskets and O-rings.
Just need some direction on how to approach this issue on my Jaguar.

Dean

 

The crankcase breather elbow you seem to be referring to is on early 3.0 V6 engined cars up to VIN M25254. Later cars have a different hose arrangement.

The inlet manifold control valve 'o-rings' should also be renewed as they tend to perish over time and can leak causing unmetered air to be drawn into the inlet manifold and leaning the mixture. The later cars had the 'green o-ring' on each of the control valves, which is the correct one to be fitted in place of the black 'o-rings' on earlier cars.

If all the other components in the fuel injection system are functioning correctly, the inlet manifold control valve 'o-rings' and the breather elbow would be good starting points depending on the age and number of kilometres/miles on the vehicle.

 

You're in good hands with NBCat.

 

A cheap and very good thing to get is an OBD tool with live data. (Thread in General Tech, but say the ELM327.)

Look at LTFTs (long term fuel trims) at idle and 2500rpm. If they head towards zero at higher revs you have an air leak.

Failing the tool, and really just get one, check you've no sources of air leaking into the manifolds / hoses e.g. that the air filter box is shut right, not cracked and so on. There's a good pic of the car showing the vacuum stuff in the stickies.

 

Thanks nbcat I was just reading that how to. Where is the breather elbow laocated? We have 52K on the odometer and its a 2007.

JagV8 yes I do have a scan tool with live data snapshot will check the LTFT's when I get home.

Thanks guys that was a really fast response!

 

The later cars can have either a 20 or 90 degree bend in the hose and it is located near the back of the inlet manifold on the LH side. Also check the breather valve located on the RH cam/valve cover for cracks and that it is correctly seated in place.

It is also good practice to check all the crankcase breather/ventilation hoses for cracks as well as the other plastic components of the air inlet system.

 

Wow this all sounds like a lot of fun! (i'm being sarcastic)
Well I guess if I'm going to get an education on the layout of the motor this is as good a time as any, I just have too many projects going on at the moment and this couldn't have happened at a better time.
Ok thats the end of my sad rant thanks guys I will do my best to put all this wisdom into effect.
OH I did read a post that some one said it was their MAF, any chance this could be that easy?

 

Devo your 07 MY does NOT have the elbow problem, there isn't one on some 03 (again as stated above depending on MY) and up model years

Your on the right track with checking the vacuum lines for cracks, most cracks happen under the tube and out of sight, Murphys Law.

Did you perform the IMT o-ring check (found in the How To's)?

Also with throwing both codes on our engines consider cleaning the MAF sensor. In reality there is a 50/50 chance that cleaning will stop throwing the codes.

 

Yes I am going to check them (IMT O rings) later very good write up, I guess a 50/50 chance on the MAF is better than rolling snake eyes in Vegas!

 

Thanks...

Ahmen on snake eyes.. just make sure you use MAF cleaner and not carb or brake cleaner. Its to bad that our MAF Sensors are close to $100.00 to replace otherwise it would be a no brainer.

 

That may've been me. Wasn't all that easy as I spent a good number of hours searching for vacuum leaks, then an equal or greater number analyzing live data from the ecm's of two cars - one with, one without codes....then swapped MAF's.....but yeah, if I'd started with that step...woulda been way easy.....but I DID have the advantage of two cars to work with, both 3.0L S-types, one an 03 and the (problem one) 05. Good luck with it....in my case cleaning the MAF was a no-go, but putting it on another car squeezed an additional year out of it

 

If it is a vacuum leak, it might not be easy to spot visually. The best way to check for a vacuum leak is with propane. You can use brake parts cleaner or carb cleaner or similar, but propane is the safest and most effective method.

 

Take time to thoroughly check all the hoses and connections for air leaks as simply cleaning the MAF sensor may not correct your problem.

Even if your MY S-Type does not have the breather system used in the earlier cars, it is a good idea to inspect the system for any leaks or broken parts as has been suggested earlier.

 

JagV8, I need an explanation. I did a little reading when I saw your post and didn't quite understand that sentence. I came across this comment on the Internet:

"A normal long term fuel trim reading will appear to stay the same, giving a long term average of fuel added. It should be close to zero, positive or negative single digits under normal circumstances. It will fluctuate much slower, possibly appearing static.".

So, my question... If the above statement is true, i.e. LTFT's are really an average over the long term and should be close to zero, I assume the direction of LTFT movement would be from -ve towards zero? And for how long would it be necessary to take readings at 2500 rpm in order to see a meaningful change in LTFT'?

 

There are two things to consider. "long term" is relative and LTFT is actually a matrix of cells kept in memory much like a spreadsheet. It is not a single number. Thus, when you change rpm you are traversing different memory cells. The remembered values at idle and 2500 rpm would be different. In the case of an air leak, the effect of the air leak on a percentage at 2500 rpm will be less than at idle, therefore it would move towards zero relative to the value seen for idle.

 

^ yes.

They're L (long) because the S (short) ones are in time periods of milliseconds. Normally just ignore the S ones.

 

Hmm, that's more complex than I thought. My peasant-level Ultragauge just shows LTFT for Bank 1 and Bank 2. What device would I need to break out the LTFT matrix into values at idle and 2500 rpm so I can see how fast each set is closing in on zero?

 

Ok checked vac lines all looks good going to check the IMT O rings tonight.
Do you think its ok if my wife keeps driving with these codes? I drove my truck around for months with the same codes before I got the time to fix it but will this condition lead to any catastrophic failure?

 

How much do you value your cats?

 

Good point, is the engine compensating the lean condition with more fuel? and if so is that amount of extra fuel enough to kill the catalyst?
The reason I ask is that I am in the process of replacing the ball joints, tie rods and ends with a new rack and control arms on our extra car. so I am looking at least a few days before I can get the Jaguar sorted out.
Thanks Joycesjag for the great write ups I have them all printed out on my desk!