Hi all,

I know there are a few threads out there on this topic, but thought I'd post one unique to my situation rather than hijack someone else's. I've read through most of them so will be using those tips as well as the info in the DTC and workshop manuals for them.

Still, i'll be seeking advice perhaps on some of the finer points of troubleshooting or what direction might make sense to go in vs. another.

Basically these indicate banks 1 and 2 are running lean. To recap, the DTC summary gives the following possible causes:

. Air intake leak between
mass air flow (MAF) sensor
and cylinder head
· Fuel filter/system
restriction
· Fuel injector restriction
· Fuel rail pressure (FRP)
sensor fault (low fuel
pressure)
· Low fuel pump output
· HO2S/catalyst monitor
sensor harness wiring
condition fault
· EFT sensor fault (low fuel
temperature)
· Mass air flow (MAF) sensor
fault (low intake air flow)
· Exhaust leak (before
catalyst)
· ECM receiving incorrect
signal from one or more of
the following sensors; ECT,
MAF*, IAT, fuel rail
temperature

To this point, I just have glanced over it and cleaned the MAF sensor with the spray they sell for that purpose. Replaced the air filter while i was in the area. If anything, I have made it slightly worse so I suspect either the MAF was really going bad and i just tipped it over, or I've introduced a leak there between the MAF and the intake. I didn't think so, but I'll doublecheck.

here is a screenshot of the live action as seen from a blueDriver OBD unit (attached)

It looks like my fuel trim values are way high, though to be honest they seem to go up and down alot as i am driving.. not sure how long it takes to steady out over time. Also, not sure what a normal value would be for air flow as measured by the MAF sensor, it never seemed to go up much regardless of the speed or engine rpm.

I'll keep this thread updated, and post pics - maybe it will come in handy for someone. First step will be to triple-check for hose leaks, and probably replace the MAF sensor and fuel filter. Will go on from there depending.

interested in comments on the readings - anything I should be adding to the log? Any numbers standing out as being egregious?

cheers
adam

 

I reckon you would do far better to follow the advice others have been given to check if you've an air leak.

 

Certainly, we're in agreement... which is why I did state "First step will be to triple-check for hose leaks...". which I'll certainly do. Thrice. But doesn't mean i wouldn't like to have a discussion as to next steps or to learn about what some of these numbers and factors mean and how they interrelate in a friendly discussion in addition (outside of my own dry research, yuk).

Not to worry, i'm not going to spend needless money in a shotgun approach and I do appreciate any and all discussion here. On the off-chance that it is something other than an air leak, and I do believe you're right, any thoughts on the screen shot? Any items I should add or take away from the logging?

 

Forget logging at this point. Take the readings advocated so often in the other threads you mention.

 

sigh... its an internet forum. i knew the risks when i posted.

 

I had the same recurring problem on my '04 VDP. All hoses etc. checked out fine. I put a small o ring on the dipstick to seal it at the tube, and problem went away. I don't know if there was an o ring there originally or not, but none on my car.

 

Hi Adam its interesting following this data relationship.
What mileage? Mobile app does not show signatures.
As it is a feedback system, and it looks like you have high positive STFT, soo then a constant enrichment should drive the LTFT up, until STFT averages zero or LT, maxes out, which causes the error.
Being high both banks seems to indicate a common condition.

Often overlooked is the brake vacuum hope fitting that degrades and leaks air. On xjr, is at the back under TB on elbow. And cracked pcv pipes, and poor injector atomization or flow.
Keep me updated.

 

jag jones - interesting re the dipstick o-ring... I'm afraid to google that! :-D

dsetter, its just turned over 46K miles. I will definitely keep this updated! It probably is an air leak anyway, but its the discussion that interests me anyway. I hope that's all it is, as I need new tires soon and don't want to spend more $ than I have to.

I'll post the data after each iteration of attempts, might help someone in the future.

 

Sorry for the delay. Pesky day-job

OK so as i mentioned in OP, i definitely made it worse when I replaced the air filter - the tubing that connects to the intake looked like it was attached when viewed from above, however it was pulled back along the bottom edge exposing a little crescent for it to suck air through.

I tried to get a picture using my inspection mirror, but it was too hard to get it to focus... i'll keep trying.

Having done that, the performance is much better and the trim values went down to less than 10. I still have the 0171 and 0174, but the "restricted performance" message went away.

I'll keep checking for leaks but pretty sure I got the big one - so now back to where it was before anyone touched it. Still suspect the MAF but checking for leaks is cheap. I'll post the screenshot of current data logging when i get a sec, later today.

 

Best thing to do when checking for leaks is to do a "smoke test" or pull a vacuum.
You need to bock the filter when using either test

I posted details on how to make a smoke tester for almost nothing
Details here https://www.jaguarforums.com/forum/x...-leaks-117917/

Cheers
34by151

 

cheers for that 34... i couldn't see the piccies, but it gives me some ideas.

 

This happened on mine. I had to have the intake manifold assembly gaskets replaced. The intake is a two piece construction. The leaking gasket was one of those and not the intake to block gasket. Jaguar says that the intake is not serviceable and does not sell the gaskets. The gaskets can be found on eBay for about $100 bucks. There is a company in Texas that imports the gaskets from Europe and resells them. Apparently, the intake IS serviceable in Europe. A smoke test will help identify your air leak.

 

here is the data from the drive after the other day fixing the big leak around in the intake. I'll do another update after i find more leaks/smoke test.




#2, after first leak fixed.

 

@cybercg, do you recall the company's name?

 

Ill try to restore the pics for you but the setup is simple

You just need sealed can
In the can you have a diesel glow plug and some baby oil
The op of the can has 2 tubes. One to add pressure and one as an outlet

The glow plug turns the oil into a thick grey vapor
The pressure in the can pumps the vapor out the outlet line

All you need to do is cap the air box tube. I pump it in via the cap placed in the air box
You only need minimal pressure

 

The prices have been coming down and can be purchased off of ebay from euromarque automotive. I believe that is the source that I used.

Search for Item Number 371555659622.

There are now other sources for the gaskets as well.

 

New links to the pics are in the DIY smoke tester thread

Cheers
34by151

 

Hi cyber et al.,

Is this the bit you are talking about? I think it may be leaking around this area. Not sure what the box off to the left of the junction is, or if a leak in that area would have this affect but it seems likely.




is this the area we are talking about?




It seems, barely perceptibly, to suck in MAF cleaner when sprayed in this area around the junction. Not enough to affect the engine revs etc.

If this is something other than what you were referring to, does anyone know what that box is called and whether it is serviceable?

Smoke machine under construction!

 

Its a silencer and can be elimated

More common a mod on the S/C versions to get more S/C wine

Cheers
34by151

 

Hi 34x151 - thanks for that... do you know if there is a blanking plate or similar to eliminate the part? And is it possible that if it is the source of my leak it would be responsible for this set of codes? Or are you implying it is irrelevant here?

Thanks guys learning lots!