Nissan Repair: Engine vibrates at low speed., air control valve, rubber bushings

Question
My friend has a car Infinity I 30 Model 90.
She say he car engines vibrates at low speed and runs smooth as speed is increased. Her mechanical is unable to trace the fault.
Any idea what are the possible causes for this problem.
Thanks!
AM


Answer
Asif,

The car could have a defective motor mount that would allow it to vibrate at low RPMs or the radiator bushings could be worn out.  The radiator is used to dampen front wheel drive engines and if the rubber bushings at the top mounts are worn out it will cause more vibration.  Lastly, if the engine is running rough, at idle check the idle air control valve and that the throttle body is clean.