RC car engines have a property called idle that describes the number of rotations of the engine (rpm) when no throttle is being applied. The engine is on, it is burning nitro, but it is idling, so the car should not be moving at all.
If the idle rpm is set too low, the engine is likely to die, and it will have a delayed response when you apply throttle
If the idle rpm is set too high, the engine will generate less power.
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