Good News! I just bought my 3rd XKR Coupe. Now need I to work out a new set of bugs. I had a 2000 and I just sold my 2003, all black XKR coupes. This is the best yet, a 2006 XKR Victory Edition, black on black. The first thing I noticed is that there's a odd whup or yip sound when you get hard into the SC. It only lasts a second. While driving the ten hours back I started to feel that when I really push it hard, especially from a stop that it doesn't have the same acceleration as my other two. There's no codes and it seems to be running great otherwise.

 

Three thoughts: slipping s/c belt, one fuel pump not working, MAF sensor weak...

Any codes? P0171 or P0174?

 

Nothing but that noise. My other two had 18 inch wheels and this one has 20's, but that shouldn't matter.

 

No codes? So other than tracking down the noise I would recommend a hard reset and have your transmission adapt to your driving style (there are a few posts about this) You may want to get the transmission fluid, pan and filter changed if it hasn't been done recently. You may also want to check the adjustment of your gas pedal linkage (another post). FYI There is only one fuel pump I know of in the later, 4.2L cars.

The sound may indeed be due to a belt slipping, but should be fairly easy to trace once the area of the noise source is located. Hopefully it is as simple as a belt, the SC belt is supposed to be changed every 60k but age should also be considered.

 

the noise,is that not the air being sucked in by the charger?

 

Could it be the notorious squeal/chirp of the ZF6 autobox? This TSB refers.

Mine is certainly doing it at 45k miles, even though the TSB pre-dates my XK8's build date and I would have thought it came with the new spec fluid from new!

 

If I hadn't owned two other XKR's I might think it was normal.

 

thinner kn filter allows more air in than normal as i found when i first put it in

 

I have a 2004 XKR. My fuel filter was badly clogged and once fixed the car felt far better. Some folks never change them. You only have one fuel pump so it is doubtful that is it (they went from 2 to 1 with the 4.2). You may want to check the boost, your SC could be getting tired (folks often don't take care of them). Bad plugs can also kill power. I found changing the transmission fluid fixed the transmission bark problem I had (though I had to do it twice to get the old crap out of the torque converter). Make sure the electric flap into the air cleaner opens at full throttle and make sure you are actually pushing the throttle to the floor, the full throttle switch on my car was really stiff and I found I wasn't really flooring it when I thought I was. That extra quarter inch or so makes a big difference. Also make sure your sport mode switch actually works (isn't flashing), as you know this gives you first gear and more aggressive shifting. The linier switch has a tendency to go out (mine did).