What are the causes of unstable idle speed when the engine is warm?

1 Answers
VanPeyton
07/29/25 1:41pm
The following are the main reasons for unstable idle speed when the engine is warm: 1. Poor performance of spark plugs. 2. Faulty throttle position sensor. 3. Air leakage in the intake system. 4. Vacuum tube leakage. 5. Malfunction of the idle stepper motor and idle control valve warning light. Here are some solutions to these issues: If unstable engine idle speed is detected, the first step is to adjust the idle speed. If the problem persists after adjustment, check whether the idle jet and idle air jet are clogged. If clogging is found, clean them with gasoline or acetone and then use compressed air to blow them clear. If no clogging is found, inspect the intake manifold or carburetor for air leaks. If leaks are present, tighten the screws to secure them.
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