So after having gone to the dealer multiple times with my new '08 XJR for rough cold idle issues ( 2-3 second smimmy ) and having the EGR, spark plugs and O-rings replaced, it appears that the problem may have been fuel-related...After the EGR was replaced, I started using BP gasoline ( just because I moved and the Station was closer to my home). Everything was great, until I filled up at a Mobil on the interstate...the following morning the shimmy came back...it continued until I refilled the car with BP fuel and the problem was gone....I called my dealer...they told me that Jaguar recommends BP..?!?!?!?...Does that make any sense? Can the car be this sensitive? I mean, Mobil is Tier 1 company...I had an '06 E55 prior to this and it didn't matter what brand gas i put in it...

Interestingly, the first time this shimmy ever happened I had filled up with Phillips 66 fuel ( again, switching from BP )

 

Greetings,

Good to hear that your XJR is running properly now. I expect that, with the engine performance problems gone, your exhaust smells a fair bit better as well. I transferred your post onto the "XKR smells" thread, I'd appreciate any comment you can add to that thread about any odors in your car now.