What Causes Cold Idle Shaking?

[Gregory]

Cold idle shaking occurs due to the following reasons: Poor combustion in the cylinders: The fundamental cause of cold idle shaking is poor combustion in the cylinders. Insufficient combustion leads to inadequate power output, resulting in vehicle shaking. Insufficient engine temperature: When the engine temperature is too low, both fuel and lubricating oil fail to reach optimal temperatures. Therefore, during a cold start, more fuel is injected to meet power demands. Larger spark plug gaps result in weaker ignition energy. Poor fuel atomization at low temperatures: At low temperatures, fuel atomization is less effective, requiring higher ignition energy. Over time, spark plug gaps tend to widen, reducing ignition energy and consequently affecting power output, which leads to vehicle shaking.