I only ask, as my car idles bang on 800rpm (Its an XJR) revs fine, and woudnt really make one think there is a problem....

But stand at the back of the car, and the woofle of the exhaust has a slight offbeat sound between the two tailpipes (like a car with lumpy cams - or a slight misfire)?

I also think i might have a very mild blow from my exhaust - a very light investigation makes me think it might be from the joint/olive where the downpipe meets the front section of the exhaust.

 

Out of curiosity does this occur ONLY when the gearshift is in 'Park", and then disappear when the transmission in put in gear?

If so, mine does the same and I've never been able to conclusively determine why. A few other X300 owners have commented about the same thing over the years. A few times I've thought I had the problem fixed...but I was wrong. I've pretty much given up the chase.

I've had various misfire and rough idle problems over the course of the years, some severe, others merely annoying. The car seems to enjoy tormenting me from time-to-time.

Cheers
DD

 

I don't think there's reason to worry over a woofle. I notice a woofle from my cars too. Also I think a misfire would be noticeable whilst driving, and would soon set a code.

Perhaps it is a characteristic of the exhaust system design, split to two tailpipes, with only six cylinders feeding through them?

I say enjoy the woofle. I do. It sounds deep and a little menacing!

 

Thanks for the feedback, perhaps it is nothing more than the curious 'incredibly slight' lumpiness (that you speak of Doug) when the car in put in park - I too have noticed that in pretty much every XJ i have had - Including X308/X300/XJ40.

 

My XJR tends to misfire every so often and have found my ignition coils on occasion throw a minor flash of lights when checked at night with the hood open and coil cover removed during a half hour watch.

I spoke with a mechanic about this and he was telling me the coil over boots sometimes are not efficient enough and the spark grounds to the walls of the spark plug inlets.

 

If the flashing is coming from inside the opaque-ish potting material at the top of the coil then you have a coil beginning to fail.

True, though, that the boots often fail as well

Cheers
DD

 

Hi Doug,

Yes you are right on. These are the new Prenco ignition coils I purchased. I'm keeping my eye on them to see if things will get worse. So far is intermitten and 98 percent of the time it runs great.

 

I think i may well have a failing coil - Well i am hoping so, as it would be the simplest solution!!

I noticed today that whilst the car performs fine whilst driving. The idle issue has become worse once the car is warm - with intermittent misfire that you can really feel in the car and visibly see the engine rock when looking at it.

Only happens at standstill (regardless of being in P/N/D)....

Thought i might by a new coil pack and change it over with the others 1 by 1
(i plan a plug change anyway).

Anyone bought one of these, from this seller? Price seems to good to be true?

JAGUAR XJ6 XJR X300 IGNITION COIL PACK LHE1510AB | eBay

 

Be wary!

Lot's of discussion here...with the 'green box' Lucas coils being mentioned in the last few postings:

https://www.jaguarforums.com/forum/x...0-coils-93966/

Cheers
DD

 

Both mine do the very same, kind of a low pop or hum out of sych with the opposite side. My series 3 does it to a certain extent too, most noticeable when you place your hands near the tail pipes. Sorry, not a very technical answer i know but just said i would let you know. Maybe your car is just fine. JJ.

 

One thing you can do before swapping coils is to take the cover off and start the car with the lights out, or after dark, and look for arcing. Also, a new set of Champions may solve the problem.