Hi all
I have a 2001 XK8 that has developed a lumpy idle, particularly when hot (eg when driving and then stopped at lights). It pulls well and drives as before so the rough idle is the only symptom.
The cam tensioners are right - they are the later version and have been changed anyway.
Does this sound like an air flow meter problem.
Your thoughts before I take it into the workshop please????

thanks
jd

 

An air leak or a misfire or plenty of others can cause that.

 

I would definitely monitor your live short term and long term fuel trims...at idle upon start, idle upon being warmed up, and at varying RPMs (1500, 2500 are what I use to compare)

If your trims are +8 or higher, you definitely have air leak(s) happening post-MAF sensor. They are easy to find with some basic DIY investigative skills. Any check engine lights during this rough idle?

 

I had experienced similar symptoms about two months ago. It began as irregular idle after engine warm up only at the red light or stop signs. I was able to smooth it out by shifting into N (alleviating the load), but that stopped helping as time progressed. I HAD NO CODES WHATSOEVER.
Then I pulled all the plugs to see if they're fouled of whether there was oil in wells....Neither. To my surprise, the car went back to smooth after reinstalling. Only for a couple days though .
Then it started getting worse and I finally got a code stating misfire on 2nd cylinder.
Without the code I'd have only guess work to do, but it actually was a spark plug coil. After replacing the coil as it appeared to be the easiest thing to do (besides spark plug itself which was fine), the car purrs just like new again.
Hope this helps