Took my XKR into a garage due to bad running/misfire, they diagnosed it needed the supercharger rebuilding. It got sent for rebuild and the rebuilder told me it was fine but I had it done anyway as it was with them. Picked the car up when the garage had refitted it and it went wrong again on the way home. This was last year and I packed it away as I’d fallen out with it and already spent lots on various other bits.

Got the car out again to tackle this, fault codes P0303 cyl 3 misfire, P0307 cyl 7 misfire, P0300 random misfire. Pulled the plugs, they were oily in the wells so I replaced the plug seals and cam cover seal. Fault codes gone and runs fine. Why the garage didn’t pull the plugs for a misfire I don’t know but it seems the seals were letting by.

 

You could have just blown out around the plugs with compressed air to clear it

 

Indeed. Leaky boss seals is a fairly common issue. A garage best avoided, IMO.

 

+1 . . . I agree with Michael.

If you are reliant on a workshop to diagnose, check and fix oiled plugs, it's high time to look elsewhere for your go-to garage. Perhaps I sense you know this already because I sense your frustration. Don't know your location, but others here may help with local knowledge if you advise.

OTOH, you have pulled out the tools, done yourself what any competent shop should have done . . . and you have fixed the problem. Good work on replacing the cam cover seal as well as all plug seals.

Cheers,

 

New plugs are so cheap, it is worth to check and see if that is the problem. For $60 bucks you either fix it or get more diagnostic information. Glad it worked.