I have a beautiful 95 Jaguar XJR. Here we go, I started my car one morning on a fairly cold day and the idle was terrible from the get go, lots of on and off rough bogging. The engine was shaking with the bog.. then I also noticed the bag of rocks sound meaning my coupler went to crap too! Took off the SC belt and the bag of rocks sound went away but the rough idle was still at large. Noticed after the car got nice and warm the rough idle disappeared though! So days later I replaced the SC coupler and the idle problem on a cold start made the coupler go bad again!? I don't know where to start, hope I gave some decent info. Ask me questions! I need help!

 

So you rebuilt the supercharger, but still have the same issues?

 

So did the coupler get torn open by the rough idle? Sounds like a possible motor mount issue letting the engine move more than it should.

 

SC is rebuilt and yes, the stock coupler still came apart due to the idle. Threw in a solid coupler the other day and it has been going strong, but still the initial rough idle is there, especially when I am in drive at a stoplight/stop sign. The harsh bogging goes away after a half hour or so. The mounts are still good as well. I also noticed during this half hour of crap, my car fails to shift correctly when I am going about 50 mph, feels like the wheels are not syncing up making it shake unless I push on the kick down sensor or let off on the pedal a little. Again, all problems go away after the car is nice and warm. I've cleaned the MAF, changed spark plugs, coils look good, air filter looks good, etc. I know this isn't some major problem but I am stumped