XJR 6 misfire

[oldDBS]

My 95 XJR 6 has developed an annoying intermitent misfire. Today's episode started on the return leg of a 160 mile round trip to work - came off the M4, sat at lights for a minute then set off. Sudden loss of power, car driveable but not happy. I've run a fuel system cleaner through & had my local specialist check fault codes, coil KV output & clean the throttle butterfly and assembly, all to no avail. Any ideas ?

Cheers, oldDBS.

[.richard]

Is the fuel filter ok? Should be changed at 60,000 miles.

[melhook]

Its probably a coil breaking down. remove coil cover, ( 3 torx screws), remove bolts holing coils in. start the engine, and lift each coil ( about 1 inch from top of plug ) one by one, you should hear a loud arcing as the coil shorts to earth, dont worry its safe as long as you dont totally remove coils from their holes. if you dont hear the coil arcing, then it will prbably be breaking down under load. they are quite a commom failure point, dont always show up as a misfire when you would expect them too. hope this helps, any more questions, or keep us posted.

[trooperiziz]

Mine does this every so often. A liberal coating of WD40 on the leads and plugs sorts it out for a month or two, then I do the same again.

Sure, it really needs some proper investigation into the electrical problem, by my way is a lot cheaper

[oldDBS]

Thanks guys, the car has just had a major service so new filters, coils been checked - all ok. I'm going to run some fuel system cleaner through again, the car's had very little use over the past 7 years (1500 per year, 50k total), I've done 2500 in it this month ! Keeping my fingers crossed for a slump in oil prices too.

DBS

[DrDeAtH]

coils take about 5 mins each to change and is an easy home fix, so saves on big bill at jag dealer.

buy them online at www.britishparts.co.uk for a good deal and quick delivery.
think i paid about 60 quid each plus vat

[oldDBS]

I think i've sorted it ! After much thought & asking around, I had the crankshaft speed sensor changed. I've done 1500 miles in the last 2 weeks & so far it's run perfectly.