My mechanic seems a bit stumped on it right now, so thought I'd see if I might be able to find some forum magic for help.

Have an 02 XKR that has been in the shop most of my ownership. Less than a week after purchase and road trip home, got hit with the tensioners. After replacement and valve work, now have a problem with idle. Particularly when it's just started and hasn't warmed up much. Getting quite a bit of shudder early on, though after a bit of steady city driving it seems to calm down but still there. Idles fairly steady at around 650 RPM, though CEL is on and getting lean errors. Would occasionally get restricted performance when stuck at a light, but after we opened it up again this last time haven't had that again.

Have gone through all the plugs and coil packs, no issues there. Was thinking it might be something with the exhaust since it was getting very hot with some popping. But pulled the exhaust today and the cats seem ok on initial inspection. And not ready to upgrade them til after new year when I can do the nameless swap.

Car runs fine under load and acceleration seems fine. And it ran beautifully prior to the breakdown for the tensioners. Any input would be appreciated as I'm really looking forward to finally being able to enjoy it. Almost 5 months of ownership, and maybe 1/4 of that time driven. Been joking that my shop lets me borrow it now and then!

 

Try cleaning the connector to the MAF-IATS with Electrical Contact Cleaner.

Also, inspect the Accordion Folds in Intake Air Duct for Leaks.

 

Since presumably the heads were off for the valve work, I would be sure there isn't an issue with the head gasket(s). If there is a leak, it could run lean and theoretically could be worse when cold and as things warm up they expand and the leak may not be as bad once hot.

 

Possible vacuum leak? Not really a common problem on these, but some cars with plastic manifolds will leak at the manifold joints slightly whe cold, and then straighten up as the engine temp comes up. Easy enough to check by squirting a bit of water or ? in and around the intake when the issue is pronounced. If the engine straightens up temporarily, or falters temporarily when doing this, you may have found your problem.

 

Throttle body gasket and egr gaskets too could be suspect. Not supposed to reuse a tb gasket, spend $8 and change it. My 03improved greatly with those two maintenance items. Pull all your Norma connectors on the manifildsand replace the o-rings with viton ones...don't forget the Norma on thethrotthe body, and the boring on the dip stick too.all little leaks add up.

 

My 02 XKR does the same thing, usually if I try to go uphill in the first 200 yards or so. After that no issues. I just live with it and try to warm the car up beforehand.

 

Don't know if you had this fixed yet or not. I had an XJR in the shop yesterday with a cold idle issue. Ran well otherwise. I suspected an intake leak, so I used a smoke generator attached to the throttle body, and it showed a leak from a badly installed throttle body gasket. Once I replaced that gasket, it ran glass smooth. If you have access (by way of a service shop) to a smoke generator, this might show you the problem on your own car.

 

You may want to look @ the fuel trims when you are having the problem. The other thing to try is disconnect the vac line to the fuel pressure regulator & see if it smooths out.

 

Thanks for the suggestions. Going to talk with my mechanic on Monday and run a few things by them. As of Friday afternoon, according to my mechanic, Jag support is recommending opening it back up and checking the timing. They're thinking there's an issue with the new chain where it's not stepping down the way it should. So going to see what happens with that.

This will be the 4th time we've pulled the supercharger off it. May just have them send it off for a rebuild this time if we have to order another chain kit.

 

Put a bit more time into it this week. Everything was good on the timing but swapped out the chains again per Jag. Tried the smoke machine with it, no leaks showing with it. Tried testing the coil packs again, but no real change. Though did have some oil in two of the plug chambers when we pulled the coils. Ended up taking off the valve cover on that side and swapping out to another one just to see if maybe there was warping with the plastic cover. seems a little more stable after this last bit of tinkering but still rough.

Mechanic is wanting to have me bring it back in when I can spare it for a couple weeks again. Going to pull the heads again and see what we have on that side. And going to have him send over a copy of the codes it's throwing and/or the AutoLogic reports.

Though half tempted to take it on a road trip to the nearest Jag dealer and see if they can at least diagnose without an excessive wait time/breakdown.