What are the causes of idle stop failure?
2 Answers
The causes of idle stop failure are: 1. Sparking phenomena in high-voltage coils, high-voltage wires, distributor caps, cylinder wires, or spark plugs, resulting in reduced ignition energy provided to the cylinders by the spark plugs, causing engine idle vibration; 2. Incorrect ignition timing of the distributor. The engine speed at idle is called the idle speed, which can be adjusted by modifying the throttle size and other methods. Solutions for unstable idle and vibration: 1. Clean carbon deposits from the engine and idle motor; 2. Clean the fuel system; 3. Replace spark plugs, high-voltage wires, and ignition coils; 4. Clean the air filter and throttle; 5. Replace aging engine components.
As a seasoned mechanic with over a decade of experience, I've found that the most common issue with idle stop failures is sensor malfunctions. That battery charge monitoring sensor is particularly finicky—it stops working at the slightest voltage fluctuation. Then there's the start-stop button's poor contact; it might just be a small button, but if the metal contacts inside oxidize, the system won't receive the signal. Once, while inspecting a car, I discovered cracked engine mount bushings causing excessive vibration, which led the system to completely lock out the stop-start function. Oh, and nowadays many vehicles rely on brake vacuum levels to determine activation—if you press the brake lightly or there's a vacuum hose leak, the system won't engage at all. These scenarios aren't actual faults, but owners often mistake them for system failures.