Hi All,

My XJ8 is running great as a general, but I have an uneven idle when the AC and the fan is on full boost. My idle is without AC and Fan steady 650-700rpm (hard to read the exact number) and it is also even when turning the steering wheel standing still. When I apply the AC alone the idle is unchanged. If I apply the Fan alone full boost the idle is unchanged as well. When I apply the AC and the fan together full boost my idle speed will bounce around, from 450 – 1000rpm - the car is just about to stall before the car increases the idle speed. Has anyone experience this and/or knows what courses this?
Thank you in advance
MTW

 

This actually only happens when the weather is upward of 90-95F otherwise it is fine - my jag simple does not like hot weather.
I am thinking it is a dirty throttle body - is it recommended to clean the throttle body your self?
I just replaced the engine air filter and it helped no doubt - now the idle is just jumping 50rpm up and down.
Hope some one has an idea
Thanks

 

I had similar problem, not AC related. Turns out the clamp that connects the air hose to the throttle body was a bit loose and it was sucking some air from there. It was happening in hot days when the engine is rather hot. Mine actually stalled a few times.

Dealer replaced the clamp and re-flashed the ECU according to some TSB.

 

Thanks Veffremov,
I thought about a leak somewhere and checked the intake hose but did not find anything to be lose, but it can still be leaking - I will take it all apart and assembly it again - if that does not work then I will take it to the dealer.
Thanks for sharing your experience
MTW