According to the owner, the Honda Accord (Accord) sedan in the idle when there is engine vibration failure, and thus lead to the steering wheel kept vibration. In fact, at this time the engine is not fire, so to determine the root causes of the vibration may exist in the engine suspension.
    1990 ~ 1997 annual production Honda Accord automatic transmission of the engine suspension with a new type of vacuum device, then the suspension also has an electronic control function. Although the Honda Accord engine rear suspension system does not have automatic fault diagnosis function (ie, no fault code), but the diagnosis of the system failure is extremely convenient. The specific principles and methods are as follows.
    1. Failure analysis
    The rear suspension has both hard and soft operating modes. At an idle speed of less than about 850r / min, the electronic control module ECM sets the suspension in a soft mode to achieve a smooth idling speed; when the speed is raised, the suspension enters the hard mode. Among them, the engine speed is ECM control suspension mode of the main input parameters. In addition, the solid blue wire on the distributor is the channel of the speed signal input ECM (for the Honda 2.2L engine as an example).
    The rear suspension includes two hydraulic chambers and a rotary valve. The ECM switches the soft and hard operating modes by changing the phase of the valve. Close to the rear suspension of the small device, exactly like the old-fashioned US engine commonly used hot-rise film. The device is the engine rear suspension drive device. In the idle conditions, the solenoid valve connected to conduction. Vacuum through the solenoid valve to reach the drive device. When the diaphragm of the drive is moved in vacuum, the diaphragm pulls the connecting rod, thereby changing the phase of the internal rotary valve of the suspension, i.e., switching the suspension to the soft mode. When the speed exceeds the idle speed, ECM will be the solenoid valve grounding, that is, the vacuum within the drive device, so the suspension re-enter the hard mode.
    If the rear suspension is stuck in the soft mode, the range of deformation of the suspension is large and may seriously affect or interfere with the other suspension of the engine. However, when this failure occurs, the driver is usually not immediately aware of.
    And once the rear suspension is stuck in the hard mode state, the driver is usually able to feel the above-mentioned idling shaking, and this vibration is more intense when the air conditioner is turned on. In this case, the most obvious symptom is the vibration of the steering wheel. In addition, improper engine installation can also produce such as in the brake when the "click" or "crack" sound.
    Before making a final judgment, it is necessary to carefully analyze the detailed history of the faulty vehicle and the many factors associated with it. For example, damage to the front torsion bar of the engine can also cause steering wheel vibration. The best way to check the torsion bar is to remove the upper and lower bolts and pivots of the torsion bar and remove it. If the bushing has been damaged (especially the upper bushing), the torsion bar must be replaced. If the torsion bar bushing is in good condition, do not install it immediately, wait until the following maintenance steps are completed.
    Ignition system fire and throttle coke will also cause the steering wheel to vibrate when braking. In addition, the idle speed too high will lead to steering wheel vibration failure. This is because the idling is too high to cause the engine to be idle in idle mode.
    Replace the timing belt, if the balance axis timing phase improper, there will be the above idle and acceleration when the steering wheel vibration phenomenon, but this time the vibration will be more serious.