since i have had it my xjs has had a unsmooth spot when idling, a bit like a misfire but i can' tell if thats what it is exactly. Putting octane boost, fuel cleaner, and premium doesn't seem to affect this but I just want to know what it is.

I was thinking maybe one of my injectors is dirtier than the rest since it seems to be at a specific spot? Or maybe one of the plugs is dirty ? Neither are exactly things i want to delve into when they aren't the real problem because it is a bit of work....

 

Both are plausible causes.

Sometimes it's difficult or even even impossible to pinpoint the exact cause of a subtle problem.

Sometimes there's a stack-up of problems contributing to the symptom.

Sometimes you just gotta go for it and hope you hit paydirt :-)

I've found that *professional* injector cleaning has helped the idle quality on all three of my Jags. By professional I mean either removing all the injectors and sending them to a specialist (best method) or having a shop use an injector flushing/cleaning machine/process to clean them on-the-car (next best). Although some fuel additives/cleaners are very good they can take much longer to work...if they work (third best, and not too expensive)

Others will chime in

Cheers
DD

 

compressor is out because i was cleaning some stuff checked 6 plugs...the ones i can get to obviously.

all 6 were at about 40 instead of 25. maybe when i get all of them done this will help. Need to replace plugs and wires obviously..