XJR X308 starting issues

[andrewrob]

My father inlaw's XJR has recently developed a starting problem in which the car turns over and struggles to start until you press the accelorator down slightly.

It has stalled once recently whilst approaching a roundabout but apart from that it runs normaly.

Would this be a spark plug issue or something else?

The car was registered in November 99 and has Nikasil liners. It also idles at around 600rpm.

Thanks in advance

[Jaguar steve]

Does the car turn over at the normal speed when you try to start? if not the battery may be on it's way out.

The XJR should have plugs replaced every 30k, and not the 70k of the n/a cars. If this has not been done then this may well be the problem. The only other thing I can think of is the throttle body may need a clean out with carburettor cleaner. If there's a build up of contamination on the butterfly and body bore this may well affect starting and low speed running.

Check the battery is good, check the plugs are the correct type (NGK PFR501E with a 1.0mm gap IIRC) and take off the air intake trunking and have a clean round the butterfly valve. If it's excessively contaminated then an oil change may be overdue. Lift the oil filler cap slightly when the engine is hot and idling to see if there's excessive fuming or pressure.

I'd also take off the part load breather pipe - that's the black flexible pipe on the top of the LH cam cover towards the front - to see if the calibrated hole in the cam cover on the LH cam cover is clear. Use a 2.5mm drill bit turned by hand to clear it out if it's blocked.

Do this and then run it for a while and see how it goes. If problems persist you'll have to get a proper diagnostic and there's an outside chance you may need a new throttle body. There was a recall on all the earlier XJs for this if drivability problems were experienced but unfortunately that has oficially expired now.

[andrewrob]

I can see why you have that username now! The car is turning over at a normal speed.

I'll check everything else you have listed above and will fit new plugs as these have been in for at least 40k miles if not more.

Thanks for your help, I'll let you know how it goes

[Jaguar steve]

andrewrob said:

I can see why you have that username now! The car is turning over at a normal speed.

I'll check everything else you have listed above and will fit new plugs as these have been in for at least 40k miles if not more.

Thanks for your help, I'll let you know how it goes

You'd better check the plug number I gave you is the right one for the XJR - I'm not absolutely sure it is. Have a look on ebay for plugs rather than pay full price for them, you'll see why I said that when you start looking and see how much they are... Each...

Put the plugs in, change the oil for a 5W/40 full synthetic - Fusch Supersyn is the cheapest at about £16 for 4 litres (from GSF) and one of the best you can get, check the breather hoses and restrictor for blockages or leaks, give the throttle body a good clean then give in to the obligation to take it out for a sound thrashing.

That might be all it needs

[Markymark69]

andrewrob said:

I can see why you have that username now! The car is turning over at a normal speed.

I'll check everything else you have listed above and will fit new plugs as these have been in for at least 40k miles if not more.

Thanks for your help, I'll let you know how it goes

He should be called Saint Steve, the mans a gent.

Not only did he offer to help me out but was a wealth of info, top man.

[drummerboyXJR]

Steves right about ebay for plugs, theres a guy who lists jag-boxed ones 8 at a time, on auction. I managed to get a set for £47, a fair saving on dealer price.

[Tame Technician]

andrewrob said:

My father inlaw's XJR has recently developed a starting problem in which the car turns over and struggles to start until you press the accelorator down slightly.

It has stalled once recently whilst approaching a roundabout but apart from that it runs normaly.

Would this be a spark plug issue or something else?

The car was registered in November 99 and has Nikasil liners. It also idles at around 600rpm.

Thanks in advance

Sounds like the begging of a throttle body problem to me. Whip the inlet trunking off and give the throttle body a good clean with carb/inlet cleaner.

[andrewrob]

Jaguar steve said:

andrewrob said:

I can see why you have that username now! The car is turning over at a normal speed.

I'll check everything else you have listed above and will fit new plugs as these have been in for at least 40k miles if not more.

Thanks for your help, I'll let you know how it goes

You'd better check the plug number I gave you is the right one for the XJR - I'm not absolutely sure it is. Have a look on ebay for plugs rather than pay full price for them, you'll see why I said that when you start looking and see how much they are... Each...

Put the plugs in, change the oil for a 5W/40 full synthetic - Fusch Supersyn is the cheapest at about £16 for 4 litres (from GSF) and one of the best you can get, check the breather hoses and restrictor for blockages or leaks, give the throttle body a good clean then give in to the obligation to take it out for a sound thrashing.

That might be all it needs

A big thank you Jaguar Steve! Changed the plugs and it cured the starting problem straight away, cleaned the throttle body and butterfly and now it doesn't stall! It had got to a point where it was stalling every time you used kick down but hasn't done it once since cleaning out.

[Jaguar steve]

andrewrob said:

Jaguar steve said:

andrewrob said:

I can see why you have that username now! The car is turning over at a normal speed.

I'll check everything else you have listed above and will fit new plugs as these have been in for at least 40k miles if not more.

Thanks for your help, I'll let you know how it goes

You'd better check the plug number I gave you is the right one for the XJR - I'm not absolutely sure it is. Have a look on ebay for plugs rather than pay full price for them, you'll see why I said that when you start looking and see how much they are... Each...

Put the plugs in, change the oil for a 5W/40 full synthetic - Fusch Supersyn is the cheapest at about £16 for 4 litres (from GSF) and one of the best you can get, check the breather hoses and restrictor for blockages or leaks, give the throttle body a good clean then give in to the obligation to take it out for a sound thrashing.

That might be all it needs

A big thank you Jaguar Steve! Changed the plugs and it cured the starting problem straight away, cleaned the throttle body and butterfly and now it doesn't stall! It had got to a point where it was stalling every time you used kick down but hasn't done it once since cleaning out.

Mon Pleasure .. A sorted car for the price of a set of plugs and some carb cleaner can only be good news