Hi,

Rolling from say 20-30 mph, and giving it full throttle acceleration through the gears, I get an acrid smell in the car (not exhaust or tyres) more like a slipping manual gearbox clutch than anything. Could be my imagination but doesn't feel that like its slipping..

No smell at normal day to day throttle/acceleration.

2004 x350 XJR. No EML lights. Running a map, intake and sports cats/exhaust, standard pulley.

Any guesses before I chuck the car in the garage?

 

Sniffed yer serpentines lately?

 

Oh... see now that makes sense!!!!!! Hadnt considered that!

I like that for two reasons...

1: I like the idea of replacing a belt more than a gearbox...
2: Belt squeaks on cold damp mornings.

 

Idler isn't too bad, either, but not all that much fun if it needs an Alternator, PSU pump, Air-Con, or water-pump replaced, too.

Check to see if it is getting a spritz of leaking coolant pissed onto it under full-gallop, too.

 

Suggest turn off stability (AKA: traction) control - button on shift console - and try it again.
May be rear brakes intervening to prevent wheel slip. These cars (stupidly) have open diff, and XJR can easily spin rear tires.
Easy to cook rear pads when hammering out of slow corners, as I've learned... You can tell by the smell