What Causes Engine Idle Stability but Car Vibration?

[DelIker]

Reasons for engine idle stability but car vibration: 1. Clogged fuel injectors: Due to gum deposits in gasoline blocking the injector nozzles, causing inconsistent fuel injection among injectors, leading to uneven cylinder operation and engine vibration; 2. Abnormal water temperature: The vibration may be caused by insufficient coolant, thermostat failure, non-functioning fan, or inaccurate temperature switch; 3. Low idle speed: The engine idle speed is preset in the ECU. When the RPM drops below a certain threshold, the car computer will automatically adjust. If the idle is too low causing vibration, it indicates the condition is beyond the ECU's control range. Some vehicles have an idle adjustment screw on the throttle body, while others don't. For non-adjustable models, check the idle control valve, throttle body, air flow meter, vacuum sensor, and adjust ignition timing to increase idle speed.