XK8 a little lumpy on start up

[JonBrydges]

Hi all.

I have had my XK8 (97 P reg 4L Coupe)for about 2 weeks now and it seems to be a little lumpy when stationary when just started up and until warm. Once it has been going for 10 minutes, it is fine and purrs nicely.

Are they just like this?

If so, does this come and go, as it isn't always as bad as other times?

Also, it seems to have a tappity rattle coming from towards the top of the engine - this still exists when it is warm, and I'm sure I can hear it when putting on the power.

Like a tickatickatickatickaticka type of sound, but not like a reolving belt or anything.

[GavinPearson]

Seriously, get it checked with extreme urgency.

You may have a timing chain problem. High risk of losing an engine, so get it fixed immediately.

[JonBrydges]

Thanks. This morning was fine, and the tensioners have been changed.

Will get it looked at on Saturday morning.

[Shar2]

The ticking may be the VVT's or a leak in the EGR pipe, the later easily fixed. VVT replacement is around £220 ea x 2.

[JonBrydges]

Called garage and they said the same. It could be the coils or the VVT. Going to see them on Saturday.

Will keep you updated.

[Shar2]

Normally if a coil is failing/failed you will get a restricted performance warning and amber/red light.

[JonBrydges]

Hmmm. Not getting that. Bit of a mystery at the moment.

[JonBrydges]

Been to get it looked at and the ticking / clacking is the injectors and is a normal sound.

The spark plugs need to be changed as not been done yet, so gonna try that and see what happens.

[Trooper2]

Your lumpiness at start up, until warm and they enter closed loop, may be due to Jaguar tuning the V8s to run leaner than they maybe would have liked to, to meet emissions standards. S-Type V8s are known for setting mis-fire codes at start up due to running so lean, especially in cold weather. At least that is the case with the way they are tuned in the U.S.

[JonBrydges]

Thanks for that. I chnaged a pipe which had been sealed with tape and that helped a little, then changed spark plugs today.

Gonna see what it is like from cold tomorrow and let everyone know in case they experience the same thing.

Also, a mate of mine is a certified Jaguar Engineer ( I didn't previously know this) and he had a look over it and it seems to be OK and nothing too much to worry about.

Thanks to everyone who posted