The body and seats shake slowly when you are cranking the engine. This vibration occurs immediately upon cranking, and stops the moment the engine has started.
Main causes
Engine torque fluctuations
Body resonances
Mechanism
1.When the engine is cranked, pressure fluctuations in each cylinder cause the engine to shake around its roll axis.
2.An opposing force is generated in the body by way of the engine mounts.
3.This force then generates vibrations in the vehicle body.
If unusual sounds accompany these vibrations, you must check the engine mounts for proper alignment, and to see if the exhaust pipe is hitting the body anywhere.
Vibration at idle is likely to occur when the air conditioner is turned on, the blower motor is operating, the automatic transmission is except “N” or “P” range, the foot brake or parking brake are applied, and the vehicle is at a standstill.