Rough Idle/Vibration - 99 SL2

During the last year my 1999 SL2 has developed a vibration/roughness at
idle. It also seems to idle faster than when new.

I tried new Bosch plugs, a new Bosch Oxygen sensor, new air cleaner. I
found a buildup in the throttle area, and cleaned that off. I've run about
12 bottles of injector cleaner through it (the kind you add to the gas
tank). None of these things affected the vibration/roughness.

I've listened for vacuum leaks, but I can't hear any.

I've changed the oil every 3000 miles.

Acceleration and performance at all other speeds is excellent--seems to be
like new.

I live about 70 miles from the nearest dealer, and it is hard for me to get
off work. I would like to resolve the problem myself if possible. (When I
bought it, they said a new dealership was going to open in my town.)

Any ideas or suggestions would be appreciated.

Thanks,
Dan

 

Dan,

Although impossible to diagnose without seeing the vehicle, this does sound
to me like a vacuum or intake manifold leak. Is it possible you loosened a
hose when you changed the oil, replaced an air filter, cleaned the throttle
body replaced the sensor, etc? Keep looking and maybe you will get lucky.

Bob

 

have you checked your mounts? worn motor mounts will cause vibrations at
idle.

Just a thought

Jeremiah

 

Worn mounts don't cause vibrations, they fail to damp the vibration that
is already there. If they caused vibrations salvage yards would have to
locate away from major tectonic faults. ;>)

 

ok, bad wording, just getting off work 10 hour night shift, maybe i should
take a nap before replying to posts

Jeremiah

 

Hi,

Did you get this resolved? My SL2 has just started doing this and I'd
like to get some idea of what might be wrong before sending it off to the
dealer.

Kirsty

 

Hi,

Did you get this resolved? My SL2 has just started doing this and I'd
like to get some idea of what might be wrong before sending it off to the
dealer.

Kirsty

 

I've had this problem ofr some time with my SL2, but I have been unable to
fix it.

Let me know if you find out anything.

Thanks,
Dan