When my throttle body was playing up I had rich codes as well as the fuel trims being all over the place. I was also getting limp mode from time to time. I cleaned my two year old MAF sensor which helped for a short while. The car then threw P1122 and P1316 which made me swap the TB - it's been fine ever since. Interestingly the gear changes are much smoother as well and it doesn't want to almost stall when coming to a stop sign. I know from your other post you're also chasing a limp mode problem so I just wanted to make you aware of my experience with similar faults/codes.

 

I had the same problem last year. Tried everything from new MAFS, new fuel pressure reg., removed injectors and had them cleaned, new plugs, probably a few other things. Also took it to three different service centers including a Jag dealer, Jaguar of Naperville. The dealer did a "Peace of mind" diagnostic service with a "Know your vehicle" report. It cost just under $150.00 and was will worth it. They found both upstream O2 sensor needed replacing. Thy wanted $850.00 to replace them, so I did it myself. Went about 500 miles with no codes, then got both P0172 and P9175 back. About that time my trans went out so I had the shop working on the trans also replace the 2 downstream O2 sensors. I have put about 4,000 miles on the car since then and only had P0172 appear once in the 4k miles. The only thing I can think it might be is the throttle body and if I have more problems, I will send it in to be rebuilt. FYI, My codes with the "restrictive performance" light would only stay on for a few seconds to maybe 5 minutes. Most of the time under a minute. Hopes this helps with your problem.

 

Thanks for the ideas guys. My luck ran out again today and another RP message. The failsafe seems to be cured, so I will be looking into this more since it seems to be more than just the air leak.

 

Your EGR Valve bolts to engine have come loose or have fell out.

Remove the throttle body, check the 2 8mm bolts holding the EGR to the Engine.

They are either missing are out and the egr is not attached to the engine, allowing raw air and RP .

The ecm will dump fuel in resulting in rich codes or lean codes.

This is a 30 minute job, that will fix your problem

 

I don't think the XK8 has a EGR valve.

 

check around , raw air is entering from somewhere,

have a shop smoke test it, that will show you

 

Ummm..... I'm not sure what "smoke check" means to you, but in my world, the LAST thing I want is for Kitty to be smoke checked!

I've got plenty of gremlins keeping me company without THAT.

 

lol its a procedure shops use to find vacuum leaks to get you out of restricted performance and running rich or lean

 

This is what I think I know about your problem. I am not a certified anything, just a back yard mechanic who spent a bunch on time trying to fix my Jag.

With P0172 and P0175 codes the engine is running to rich. Too much fuel and not enough air is going to the engine. The O2 sensors are telling the EMC that there is unburned fuel left in the exhaust. One of the sensor are telling the EMC that the engine needs more fuel or the injectors are adding more fuel then it should, either a leaking injector in each bank or to high fuel pressure in the fuel rails.

This is from JTIS for reasons for a P0175 code
Engine misfire, Blocked air filter, Fuel system return blockage,
Leaking fuel injector(s), Fuel pressure regulator failure (high fuel pressure), ECM receiving incorrect signal from one or more of the following sensors - ECT, MAF, IAT, TP.

I also read on the internet that it could be the o2 sensors giving a "false" reading due to age. P0172 and P0175 code are hard to figure out as there is no one thing wrong. It's telling you that, once is a while the engine is running to rich. It is not caused from a broken sensor that has stopped working, such as no reading from the temperature sensor, but a sensor that is telling the EMC the wrong information. A broken sensor would show a different code that would tell you it was broken. It could be a wiring issue, check all your connections. You start getting into short term and long term fuel trim which are really confusing. This is what causes the codes. The ECM is telling the fuel system to cut back on the fuel going to the engine but it can not cut back enough. So the EMC is telling you there is a problem. Good luck and I feel your pain.

 

The only Codes my car ever had were a un-expected P0172 and P0175 with a RP message.

I cleaned the MAF-IATS Connector, cleared the codes and they have not returned.

The connector contacts looked perfect prior to cleaning but cleaning them with electrical contact cleaner seems to have fixed the problem.

This was 2yr ago at about 35000mi and OK since then.

Air leakage after the MAFS would normally cause the P0171 and P0174 Lean Mixture Codes.

 

Given that this issue is rearing its ugly head again (mostly when loping around town) I think I'm going to bite the bullet and do the O2 sensors. I feel a little bit like I am throwing stuff at the car with the hopes it will behave sometimes. I will keep you updated when I get this done. I hope between this and my efforts to fix the TPS problem that the car settles down. I had a little over a week of glorious driving (including a 500 mile road trip for our anniversary) before these ongoing issues reoccurred so it is a little disheartening, but I knew it wouldn't last.

 

I have never had an engine light ( orange) or restricted performance light pop on ever. I just had new plugs installed @ 40k miles, Spark Plugs were BKR6EIX # 6418 NGK and now this is my new message. Mechanic claims its un related?
It lights up restricted and then goes away after a few miles. The code shows PO175, bank 2 to rich but runs fine. The engine light stays on of course. I have cleared it and its back again.

We checked for any air leaks as well.

Here is the crazy part, the service center I went to claims it needs re flashed with all the needed updates. There is a TSB that claims this similar issue with" restricted performance" and this is the cure?

I also called Jaguar USA and ran my Vin#. They claim no updates were ever made on this car. If so the dealer would of put a sticker to indicate this on the door as well.

So I thinking I have to go to the Dealer for 300 bucks..

Any advice would be greatly appreciated.

 

Lean is what you get with an air leak, not rich.

 

Here's the list of likely suspects, since they changed plugs hopefully they didn't damage a injector or the regulator.

Blocked air filter
Fuel system return blockage
Leaking fuel injector(s)
Fuel pressure regulator failure
(high fuel pressure)
ECM receiving incorrect signal from one
or more of the following components:
ECTS, MAFS, IATS, TPS

 

Now it loves to stall... Running way rich ! It has never had any issues until this plug replacement, fuel, air and oil change. Seams pretty routine for maintenance. How can you mess that up huh??
I now have to take it to the dealer because the last shop claims its over their heads and claims the car needs the computer flashed. I called Jaguar USA and it has never had any computer updates per my VIN.

I'm sure this wont be cheap !

Personally seams more then a coincidence to me.

 

Something easily done is remove the air filter.. (clean maf while you're there) with maf cleaner I have the odd feeling your getting restricted air so try running without the filter in, may not be it but if it is you'll save some $$

 

Loanking,

you may have become a victim of the infamous xkr two 8mm egr to throttle body bolts have worked themselves loose. One may have even come out.


Get a mirror, tighten em up snug, and your good.

 

If you are only getting P0175, you are only running rich on one bank. You might want to look at the things that effect that bank. If you have a code reader that can see real time info check the long and short term fuel trims. See if there is a real difference between bank 1 and bank 2. If only bank 2 is the issue then It would most likely be something in the engine after the fuel splits to the 2 banks. You can check the fuel injectors, one may be leaking, plugs, maybe pull them and see it one looks "funny", coils, clean all electrical connections to the coils, injectors and the VVT connector. These would only effect one bank. Also check the O2 sensors, my problem seem be the downstream O2 sensors. Hope this helps.

 

Well the verdict is in:
MAF needs replaced, burned wire inside the unit. Wiring harness connecting to the MAF connector also has bad terminals. ( new wires etc. )
Needs flashed with all the updates.
The S.C has an air leaks and needs new gaskets.
Bonus, all 4 control bushing need replaced.
They started at $2600.00 and worked them to $1925.00!
Nonetheless, OUCH !!!

 

You only have 38k and I have 120+k and you need all that stuff? What the hell? Ive seen the dealer do this often to XKR owners, and the same issue still comes back. Tell them to tighten the two gold 8mm egr bolts attaching it to the throttle body and re-drive the car.before they start any unnecessary parts throwing, and ask for your old parts back, you have the right to have them for your personal inspection.

And the reason im doing this, is there are way too many people on this forum, let alone the people not on this forum, have Jaguar do this to them and they either did not do all the repairs or the problem persist.

I was quoted a engine rebuild for a "fuel washdown" condition. Saved 6 grand using a few drops of oil.