I have a friend that has a 2000 XKR. He is a little bit of of contrarian and tries at times to ignore the obvious and see something others do not. Not being critical but I always work upward from the broad-base and not at a smaller point.

He has the classic P0171 and 074 codes with the scanner showing a run up to +25 on both sides. The air intake is new and so the problem is not the common one in the bellows -I am thinking the egr screws and some the tubes in that area. However it has been suggested that perhaps the oil filler cap has a dry o-ring and that would cause the problem. There is no leaking oil form the oil cap.

Does a dry -o-ring on the oil filler cap have any relationship to a +25 on the fuel trims and thus the P0171 and 0174 codes.

A further question- if the MAF was bad would we not see codes like P0101-0106?

Thanks for your help.

Tom in Dallas/Plano

 

First the filler cap will have no affect here on fuel trims.
Second is he has modified the intake, did you perform a hardreset after the update so the FT can be reset and relearn? Check the plugs on the maf as well, if not connected correctly he maybe having false readings.

 

Why wouldn't the oil filler cap be a potential air leak? I haven't read of that being a problem but it would be the same as a leak in the breather pipes.

 

All that has been done. I am 1000% sure it is in the egr area- either the bolts or one of the rubber tubes leading from there. However that is consider by my friend as " the pedestrian thought: vs looking at the experience of people that have worked on this car for about the 20 years the model has existed. Maf has been checked and cleaned. It originally starting showing when I rode with him and notice a very rough idle and he excused that saying it was was just the nature of the engine and if course Jag did not build $85k cars to have a rough idle. I think the egr bolts just slowly loosened up and finally got loose enough to throw RP and +25 on both sides.

If the plugs were not properly connected on the MAF, would not the continuing monitoring of the MAF by the pcm cause a code to show.

I, however, have warned him not to be driving the car until fixed or he is putting in lots of gas to compensate and while we have not seen a flashing CEL (does that occur on this model and year) he may well do damage to the cats.

Tom in Dallas/Plano

 

It is a question and perhaps someone knows. But even if you have a dry o-ring, there are no oil leaks and would it cause +25 on both sides? For some reason when spraying ether around the engine and watching the codes, I think at idle I took out the oil dipstick and did NOT notice an change in the ST/LT fuel trims.

Tom in Dallas/Plano

 

Several members have reported loose egr screws, so it's a likely possibility. I removed the throttle body on a XKR to replace the egr and found both screws loose.

Check the accordion hose that feeds the egr, but be careful, it's very expensive.

 

hose has already replaced

 

Use carb cleaner and spray some around intercooler ducts that's where I found mine. A handy trick ( can use an un lite propane torch) to find troublesome vacuum leaks motor speeds up where found

 

Use carb cleaner and spray some around intercooler ducts that's where I found mine. A handy trick ( can use an un lite propane torch) to find troublesome vacuum leaks motor speeds up where found

 

Already done, but thanks.

Do not think the vacuum leak is that easy to find below the throttle with spray. I am certain that this is the problem and fix and just trying to cut off other avenues that are a waste of time.



A.
Remove the air intake, remove the Throttle Body, 4-10mm bolts, 2- 8mm bolts

3 electrical connections, 2 hoses.


The bolts for the EGR have come loose allowing the lower throttle body to suck in raw air after the MAF. AKA VACUUM LEAK

they are two 8mm, simply tighten them or replace them if they are missing.Don't over tighten.
B.
The black plastic tube that runs from the passenger lower throttle body inlet has a grommet that's worn allowing air in,pull out a lil, wipe with a clean towel, apply rtv around it, push back in, let dry overnight.

C.
There is a ambient air temperature sensor that will have oiliy residue, its on the passenger side rear upper manifold, like 22mm socket to remove I think.
Wipe the tip with a clean towel. Lightly rtv its copper washer and screw back in tight so its not leaking.

Those will cure your problems and take 25 mins to complete. You will have to reset your codes with the scanner or remove the negative, an hold it it on the positive for 30 secs. If you do that, you will have to do the window re-learn, have your radio code If applicable, and reset your clock..



But back to the original question- anyone heard of dry o-ring on the oil cap causing a problem?

Tom in Dallas

 

No, but try using a piece of plastic wrap to seal the cap, or smear some grease on the o ring.

 

Thanks. My real point is that I do not think the o-ring is a problem at all- just someone thinking that he will figure out something about the car that after 20 years of Jag and everyone working on them that no one else ever has.

Tom