Hi all i just purchased a 99 4.0 V8 S type two weeks ago and noticed an ever so slight miss in it. Figured it was just because it had not been driven in over a year till it started to get worse. And then it started to really miss fire and chug with a detonation type sound on light throttle. Changed the fuel filter and spark plugs, filter was filthy but no help. Then to mechanic for a diagnostic check where he said it needed new coil packs and platinum spark plugs. That did not work either and he did further checks to inform me that it's probably not the coil packs but rather some bent exhaust valves??? He says that it could have backfired at some stage which can disrupt the timing chain tension which will damage the valves.....?? Says it will be about $5000 in repairs. Anyone know about this problem???

 

oddly enough no warning lights. It did start to get progressively worse in steps to where it started to do the rattly detonation type of sound on light throttle. The jaguar dealer said it may just be carbon build up??? But my mechanic says bent valves.

 

Yeah i think he was saying that he did a normal compression test at first which didn't show it up because the leak is slight but then he did another type of compression test which i think involves the engine not turning over and it showed the pressure bleeding off.??

 

I'll keep an eye on it and watch what gets done...Jaguar dealer's service centre said it could be carbon build up ?? Would carbon build up be enough to cause a compression leak??