Hi guys and gals

My pride and joy seems to have developed a fault recently which is slowly but surely getting worse and I'm not quite sure of the cause.

Its a 1999 XKR 4.0. When at a steady speed (most noticeably at low speeds like 30mph) and on a constant throttle the engine will pick up speed and drop it randomly. Its feels like you are randomly applying more and then less pressure to the accelerator peddle, and can be quite violent. There is no lumpiness you might expect if a cylinder was not firing and it doesn’t seem to matter whether the engine is hot or cold.

Any ideas what might cause this? Its quite high mileage at 140k, if that helps.

Thanks everyone

Karl

 

Does it feel like it's struggling to find the proper gear?

 

Have you gone by Jaguar to see if your throttle body is up for replacement or reprogramming? This may help http://www.xclusively-jaguar.co.uk/xj04_fandi.html
Also do you have a check eng light with OBD codes? If so what are they?

 

X'S 2 SOUNDS MORE LIKE THE TRANNY IS GEAR HUNTING

 

Well what did you find?