So I've been driving the 4l XKR for a few days now and am starting to get to grips with its performance. However it seems to vary, one day it performs like a supercar and would pull the side of a house off, suck babies out of prams and tear tarmac from the road, other days it seems a little mediocre and I feel disappointed with the results of pushing the loud pedal into the plush carpet.

My mpg seems to vary as well, I drove home today foe 40 miles very sedately roof down enjoying the sun and returned only 20 mpg
Friday I drove sportingly to work and it delivered 22 mpg?

Is it just me? Is it something anybody else notices? Or do I need to start delving into the heart and spending lots of money?

I do have a small blow in the exhaust that needs the joint re sealing and clamping but I'd be suppressed if it could have such a dramatic impact.

Just interested to know othe people's views.

Thanks

 

Take note of several things:

-Is your sport mode engaged?

-This car has modest power off the line, but vast power at high speeds.

-The supercharger system is susceptible to heat soak... drive it agrressively and you need to give the supercharger a chance to cool down or you will have less power next time around. It will also be notociably more powerful the cooler it is outside. There are aftermarket solutions to help this problem.

-Your throttle cable may be in need of adjustment to get 100% throttle.

-The car is adaptive...drive it agressively and it will continue to behave more agressively. Drive it softly and it will tend to behave more softly. Keep changing your driving style and it may not feel as responsive.

 

Thanks White
I dip in and out of sports mode quite a bit so am mindful of it being on.
I found the throttle cable was a vet loose fit on the adjuster and it looks to have slipped a bit, temporary zip tie used to hold it in place.
I also found the none genuine footwell mat was hindering the full throttle position, so that's been trimmed to clear.
I'd noticed a drop off in power that returned after a few gentle miles so would think this is the heat soak issue, presumably water injection and inter cooler spraying would help with that?
It now goes like a bat out of hell again, I think the biggest issue was the floor mat, it just goes to show, start with the simple stuff ��

Thanks again

 

Intercooler pump failure is also a common issue with these cars.

Does not usually give any fault codes or lights! Just drop in performance during use. Can also cause pre-ignition/pinking under hard acceleration

Check the pump fuse for your model/year.

It would help, for future reference, if you could add the full year/model information to your sig.

 

Thanks stumpy I'll have a look at the manual and check the fuses, can you hear it running or verify that it is operating at all other than a DVM onto the loom?

Signature noted and added ��

 

Yes, you can listen for the pump running.
It is below the air filter box, next to the alternator.
It runs all the time the ignition is on, so no need to start engine.

The fuse for your year is in the Engine Management Fusebox F2 20A

 

Thanks, I'll check that one tomorrow.
Much appreciated

 

Blue XK:

See this post. (particularly the last paragraph)

https://www.jaguarforums.com/forum/x...d-79384/page7/