I cleared the fault codes, disconnected the battery for a few mins, now after a short drive at idle I have a

ltft1 13.3
ltft2 19.5
Stft1 -1 to 0
Stft2 -1 to 0

Isn't that exactly where my stft's should be at idle? I realize the ltft's are off but maybe the ECU just needs time to realize it is fixed?

 

I think you're being optimistic but try a few warm ups, then check LTFTs at idle & 2500rpm.

 

This thread summarizes my life fo the last 2 1/2 months. We've done two different smoke tests, replaced the throttle body with new gaskets all of the under supercharger hoses, lines, fittings and gaskets (all Jaguar parts - $1200 + over 20 hours labor) ; in and out of various shops even a stint at the Dealer (at $205/Hr). No one has clearly identified the problem. With all this work done, we're now looking at the computer, double checking it's programing and functioning. I haven't yet replaced the injectors on the B bank (PO174 code). HELP Ideas?

 

Hot engine, parked. What are its LTFTs at idle and about 2500rpm?

 

Have you replaced the MAF sensor yet? I had P0174 and I believe with it a P0171 which is the other bank. I replaced the MAF sensor with one from eBay for $41.00 and replaced the O rings on the breather tube between the valve cover and air intake (mine is an XK8 though) and this solved my problem.

 

Yes, we replaced the MAF sensor as well as the entire breather tubes with their new "O" rings. The car is now with the engine computer guy to ensure that this is not a computer problem.
Twice now at different times I have had this problem after adding a bottle of Lucas injector cleaner. Does anyone think that the cleaner may have loosened debris resulting in a minor blockage in an injector? Lean is either too much air or not enough fuel. Since I've replaced the entire air intake and breather system, maybe I need to look at the fuel delivery. The problem occurs at idle or low RPM driving. The Restricted Performance light goes off shortly and I don't have restricted performance of the car (actually it runs just fine with lots of power). I'm starting to think that black tape over the dash lights may be the answer..... kidding.

 

Do you have EGR? Check the accordion tube for cracks.

Have you checked the line to the brake booster? Funky brass fitting on the throttle body with an o-ring and a plastic collar. Available separately, but not listed for the XK8/XKR.

The MAF has an o-ring at the base. Check it is a good seal.

Check the dipstick, another o-ring.

Next, I would try and figure out if there is air making it in through the exhaust gasket, or cracks in the manifold. Any weird ticking sound?