The mileage is about 62 thousand km, and the 2011 TOYOTA Prado of 3 GR-FE engine is assembled. Customer response: after the 30s of the hot car, the engine appeared idle jitter, and the seat, backrest and sole felt jitter. Fault analysis: according to the customer's description, the workshop Technician compared the car to the trial drive. It does feel the jitter is more serious than the other vehicles in the reservoir, and the crew feels like sitting on the massage seat. The initial reason is that the fuel quality is bad, so the engine fuel system is cleaned, but the jitter remains unchanged. Therefore, the customer drove the vehicle to our company. After preliminary inspection, the data flow is normal, and there are red sediments on the terminals of the spark plug, and the rest is not found abnormal. Therefore, 6 spark plugs were replaced first, but the jitter of the engine did not improve. Check engine control system, there are two fault codes, namely P1603 engine stall history and P1605 idle speed instability. After the fault code is cleared, the fault code is no longer present. Troubleshooting: according to the instructions of the personnel in the technical room, all the sensors and actuator components involved in the two fault codes were examined in detail according to the maintenance manual. When the throttle body is cleaned and installed, the engine idling jitter still exists. Fault revelation: I hope the manufacturer will confirm the car's fault. Failure comment: later the manufacturer confirmed the fault on the spot, but the final conclusion is that all vehicles have this slight idling phenomenon. After inspection, the system has not found the exception. The cause of the jitter is the fluctuation of the engine's idle speed, which belongs to the normal range, because the measuring frequency of the vibration measuring instrument is about the same as that of the engine at idle speed. I have different views on this. First of all, the speed fluctuation of idle speed exists on any vehicle, and the speed range of idle speed of almost all models is almost the same. Since other cars, including the previous generation, are idle in this area, the new Prado is shaking, which makes no sense. Jitter is unavoidable from mechanical principle, but is there no countermeasure to mitigate jitter? I believe that it should be solved. For example, the material of the engine support mat is improved to reduce the vibration of the body, or to feel the vibration of the seat backrest of the customer. Is it possible to reduce the vibration by adding damping measures at the fixed part of the seat? For the fault code mentioned in the above fault, it was confirmed that the oil in the fuel tank was low in the test of the vehicle for the vehicle to carry out the ramp test, and it was not a fault.