Yesterday when I started up the XJR it seemed noticable louder. It almost is as if the supercharger is making a louder whine. It does increase with rpms, does not have to be in gear, does not sound like a belt or pulley issue and all the fluids are correct. AC on or off it still does it as well. Can't tell where it is coming from. Sounds pretty much the same from either side, front or back.

No codes except the pesky asc trac coming on when you start then goes away (but I cleaned the maf and throttle body sensor connections tonight and that seems to have gone away).

Ideas.

 

Mine is doing this too, any resolution?

 

Could be an idler pulley or the water pump. Might use a stethoscope to track the noise. Just be careful, things are spinning down there!

Good luck!

 

Yeah, resolution was a bad alternator. It was charging at 11.5 max voltage (hence the asc/trac light). Never had a charging light but replaced it and all was good.

 

its a bad alternator mines did this a while, back try to get one with a warranty cause mines ended up going out again. to test the theory get a volt test, put one on the pos and the other on the negative on the battery turn the car on, if the car battery read 14v your fine anything below its failing. swap it out to avoid problems along the road