sl 600 rough idle
 

hello to all,
i am new to this website and found it very informative. i just got a 1995 slo 600 with 62 k miles. my problem is the idle is rough during in neutral and less so in other gears. the tachometer swing aroung 700-800 and i can feel the car shake. the engine mount was just change when i bought it. i did some research on this forum and put techron additives in without much help(although i noticed the acceleration was slightly smoother) i have read about vacuum leak. my question is could this be due to vacuum leak? i noticed that the vacuum pump is working off and on every 10 minutes while i drive. i also noticed that when i unlock the car with the remote and heard a sound of air leaking near the passenger side area follow by the operation of the vacuum pump. any advice are graciously welcome.
thanks
mike

sl 600 rough idle vacuum leaks?
 

The door locking system on the sl 600 is not connected to the engine in any way. However, you do have a vacuum leak in the lock system and it needs to be fixed or the pump will wear out.

The wiring harnesses on these engines are often faulty and the wire insulation breaks down into dust. It is quite possible the top harness that goes to the fuel injectors is bad, causing weak current and thus low fuel flow to one or more cylinders. These V-12 engines are normally silky smooth. I've heard MBZ is encouraging Dealer to 'good will' replace the bad harnesses on cars up to 7 years old.

Otherwise, it's about $1000 to replace the top harness.