If I use the car everyday there is no problem at all. If I leave it for a couple of days,then when idling it misfires on one or two cylinders,have checked coils and have just fitted new plugs.As soon as I drive away it is ok,no misfiring After about 30 minutes of driving the idling is fine Am I right in thinking it is the throttle body,maybe needs cleaning ? But why does it not misfire if i use it everyday ? Jaguar mystery that I need help in solving,all comments and suggestions appreciated

 

You can clean the throttle body but that not causing the misfiring. Its coils and theyre random on times they misfire and not caonstant till they become much worse

 

OUCH, an expensive fix.better wait till they get worse so I can tell which ones,or just start buying them now till I have 6 new ones.

 

If you think those are expensive. waiting can take out the catalytic convertors and theyre alot more expensive. I buy 2 and replace 2 coils numbering them and since you dont have misfires codes youll have to say replace the first 2 and see if it stops. If it is the same then put the old ones back in and move the new ones back 2 cylinders and repeat. This is what I did on my own personal Jag since it misfires too and no codes to let me know which ones. And you cant pull up a misfire counters on this yr model

 

That makes sense and an economical way of curing the problem,thanks

 

Inspect the plugs. If a coil is misfiring the plug will be carboned (black) or possibly just soaked in gas if the coil never fires enough. Another way is to unplug one fuel injector and run the motor if it doesn't change the misfire it's usually the cylinder that has a bad coil if it runs worse or won't even start that cylinder has a good coil. Test this after its sat a few days since the problem occurs after it sits. I'd worry more about the misfire burning a hole in the piston or breaking a connecting rod more than the cat

 

if its misfiring that much it will turn on a cel. The issue is useally that you can feel the misfires especially at idle. But its just not enough to set a cylinder misfire, and usually not even frequent enough to do what youre suggesting. another way if you have a IR temp gun,. Is to shoot each exhaust cylinder exhaust pipe when accessable looking for cooler operation.

 

FWIW...just rambling.....

I'm becoming a seasoned veteran of coil failures and, in my case, there are two symptoms.

1) The "Tokyo at night" warning light craziness together with the gauges needles going ape-sh*t. Meanwhile the engine runs great.

2) Rough idle but otherwise smooth running *except* when under a light throttle/heavy load...in which case it misfires like crazy



Also FWIW....and I know this has been mentioned before... the parameters Jaguar set for turning on the CEL are very narrow, it seems. I've never had a misfire code or CEL despite many misfire events.

Cheers
DD

 

Does the IR temp gun work when the exhaust manifold runs straight back from front to back and no cylinders have their own tube?

 

bought three coils and swapped them out,same problem,replaced the other three with the first three....problem solved.Now just got to mess around to find out which coil is no good. Thanks for everyones input.

 

Cool, good to see it was fixed