hi, i have a 1998 xjr v8, as above, seems to run lumpy at idle and theres a petrol smell. In normal mode its pure boredom and seems like it would get outgunned by a 2 litre diesel. In sport mode, when floored from standstill feels fast and responsive as it should, but when moving at any speed and floored also in sports mode it seems like it doesnt want to kick down and instead of dropping a gear it seems to stay in same gear and go from 2000rpm.
Now, ive changed the spark plugs which seems like hardly anything has changed, ive also fiddled with the throttle cable, but it seems if i adjust it to have the throttle body fully opened, it will not close at idle and will remain open somewhat. I have also tightened the plastic switch underneath the accelerator pedal clockwise(tried also anticlockwise), also did nothing. HELP PLEASE?!

 

Have you got any DTCs?


Plug in an OBD2 monitor and look at fuel trims.

 

Whats a DTC? I dont have any equipment, how much is this monitor, is it only for jags or can it be used on other cars?

 

I also had a mechanic look at it with a computer connected, there were no fault codes and he sugested that i change the spark plugs first

 

DTC = Diagnostic Trouble Code.


You can pick up a cheap Blue Tooth OBD 2 reader off Amazon or E bay and use Torque app and a smart phone to read results.


Can be used on most cars after about 1997.


The code readers run from about £10, the Torque app is £4 or £5, so nothing expensive, but an essential bit of kit to keep your car on the road.

 

I take it this is what i need to get then?

 

Yes that or one similar, And the torque app.

 

Hello Ignas,
I'm new to the forum. I am experiencing the very same symptons with my 1996 xk8 coupe. The fuel smell, lack of kickdown in normal driving mode (fine in sport mode). At around 75mph (i know, i know!), foot down, the engine becomes lumpy, it does still acclerate but no kickdown.... i know what this car SHOULD feel like, something has gone amiss.
I have changed all spark plugs and ignition coil packs. Car is currently with Jaguar for a diagnostic, as my obd reader not showing any fault codes and i'm not as yet confident to read fuel trims etc.
I wonder if you managed to resolve this situation, or if indeed anybody on this forum is able to provide any pointers?
Very many thanks.