What are the symptoms of a faulty idle motor?
3 Answers
The symptoms of a faulty idle motor are: the car sometimes fails to start, but at other times it may start, and after starting, it can drive normally when accelerating. When the car shifts to neutral after releasing the throttle, it may stall or have an excessively high idle speed (above 2,000 RPM), failing to return to the normal range of around 900 RPM. It may require pressing the throttle to start and move. More details are as follows: 1. Unstable idle speed, idle shaking, high engine RPM, and similar phenomena are all caused by a faulty idle motor. Since the idle motor is a small electric motor that controls idle speed by adjusting its position via electric current, it regulates the idle air flow. Consequently, the idle motor is highly susceptible to dirt from dust carried by the air entering the engine, which affects its precise control. Excessive dust entering the idle motor can cause it to jam or fail. 2. Symptoms of a jammed idle motor Due to excessive dust entering the idle motor, it may get stuck in a certain position and fail to rotate. This can lead to incorrect control of the engine idle speed, potentially causing excessively high idle RPM. Even after the engine warms up, the idle speed may remain around 900 to 1,000 RPM and fail to stabilize normally. If the idle motor is stuck in the closed position, it may prevent the normal intake of air during idle. 3. This may result in the engine stalling after startup due to an inability to maintain stable idle speed, or the idle speed may drop too low (around 500 RPM), causing severe engine shaking. Therefore, it is essential to regularly replace the air filter and avoid using excessively dirty air filters for extended periods. Otherwise, excessive dust entering the idle motor can lead to its failure.
When the idle speed motor is faulty, driving becomes particularly uncomfortable. The most obvious symptom is the unstable fluctuation of the tachometer at idle, as if it's dancing, especially noticeable when in neutral at a red light. Sometimes the RPM suddenly drops to the lowest point, almost stalling. Cold starts are even more troublesome, with the engine shaking violently, making the whole car vibrate. Last month, I experienced this issue—after warming up, the idle speed fluctuated even more severely and fuel consumption increased. If not addressed promptly, these problems may escalate and even trigger other faults. If you notice similar signs, it's recommended to visit a professional repair shop immediately to avoid compromising driving safety. A simple cleaning or replacement can solve the issue, which is much better than costly repairs later on.
Common symptoms of idle motor failure include significant idle speed fluctuations, engine shaking after startup, and a tendency to stall. During actual driving, you may notice that the vehicle's idle speed constantly changes, making it very unstable; the shaking is more severe during cold starts. During inspection, you can test the engine behavior in neutral, such as observing the RPM surge from 800 to 1200 and then drop back down. Carbon buildup is often the main cause, and spraying throttle cleaner may provide temporary relief. However, if the issue persists, it's best to diagnose the circuit or sensors. Regular maintenance checks on the air system can extend its lifespan and prevent more serious problems.
