What Are the Causes of Unstable Car Idling?

[VanKaden]

There are several reasons for unstable car idling: 1. Air, gasoline vapor, or exhaust gases entering the intake manifold, causing the air-fuel mixture to be too rich or too lean, leading to unstable idling; 2. Excessive carbon buildup in the throttle body and surrounding intake passages, altering the cross-sectional area of the air passage, making it difficult for the control unit to precisely regulate the idle air intake, resulting in an overly rich or lean mixture and unstable idling; 3. Malfunction or damage of the engine intake system's actuators; 4. Issues such as clogged fuel injectors, blocked fuel filters, obstructed fuel pump screens, faulty fuel pressure regulators, or clogged return fuel lines, leading to an overly rich or lean mixture and unstable idling; 5. Faulty ignition modules, incorrect spark plug gaps, eroded or damaged spark plug electrodes, or excessive resistance in high-voltage wires.