Why is the car idling unstable?

[StJoy]

There are two main reasons for unstable car idling: 1. Excessive carbon buildup in the throttle body and air flow meter. The throttle body and air flow meter are prone to dirt accumulation. Most modern cars use electronic throttle bodies, where even slight carbon buildup can affect performance. Excessive carbon in the throttle body can cause throttle hesitation, severe power loss, and unstable idling. A dirty air flow meter leads to incorrect air flow signals, and since intake air volume determines fuel injection quantity, this directly results in inaccurate fuel injection, causing both increased fuel consumption and severe power deficiency. 2. Excessive carbon deposits in cylinder combustion chambers and pistons. Too much carbon in the combustion chambers can absorb gasoline to some extent, causing delayed ignition during startup. Moreover, excessive carbon deposits, mostly forming on valves and piston rings, indirectly leads to insufficient cylinder pressure, making cold starts prone to unstable idling.