What Causes High Idle Speed When the Engine is Warm?
1 Answers
Causes of high idle speed in a warm car are as follows: 1. High idle speed during startup is a normal phenomenon. 1.1 The car requires higher RPM to allow the engine to quickly reach normal operating conditions, necessitating a richer air-fuel mixture. Consequently, both air intake and fuel injection increase, leading to higher RPM. 1.2 Increased oil viscosity during cold starts: During a cold start, the idle stepper motor automatically adjusts to increase air intake, allowing more air into the cylinders, which naturally results in higher idle speed. 2. Excessive carbon buildup. Timely cleaning of the throttle body and idle speed control valve can generally resolve this issue.