1997 XK8 running rough

The other day my XK8 made a funny noise and then intermittently ran rough. The dash information box said something along the lines of “engine fault”, and “reduced engine power”. It felt like it wasn’t hitting on all 8 cylinders. The car has 53000 miles on it. Any thoughts? Thanks!

You don’t say which year, but my first guess is the timing chain tensioners have failed and the timing chain has jumped a tooth. One tooth, bad running; two teeth, destroyed engine. Do not drive it until assessed.

  1. I had them replaced not that many miles ago. Plus it’s intermittent.

Most folks think the worst, right off the bat. I had the same problem, and it was caused by not driving the car on a regular basis. Mine showed the same symptoms, and one garage spent a day and could not find the problem. Yes, the had scanners and all the other high-tech goodies. Next shop had a scanner, and some knowledge. It took eight new spark plugs and two coils. Then they told me that I had to drive the car more often. Mine is a 2001 with 81,000 miles.

And I mean sometimes
If you started the car fast then parked it then restarted it you wash the cylinders with fuel loading up the engine
If you did the chains
Fill up with premium gas
Then drive it a good long time getting the revs up
Report back

I had a weird one this week. Like the others the car hadn’t been driven for a while and had a definite misfire. I put the diagnostic box on and it said No.8 cylinder misfire. I pulled the cover off and I could see water at the bottom of the tube. A wad of paper towel wrapped around a long screwdriver soaked most of the water up and off I set with still a bit of a miss which disappeared after a mile or so as the engine warmed up and evaporated the remaining moisture.


It turns out I had a bad alternator. Seems odd symptoms of such. Thanks for everyone’s advice!

Bad alternator=low voltage & computer controlled everything=bad things happening lol. I’ve seen it before on another car.