What Causes High Idle Speed in Cars?

[LeSadie]

The reasons for high idle speed in cars are: 1. Intake pipe leakage; 2. Faulty idle control valve; 3. Idle switch not closing; 4. Incorrect valve timing; 5. Fuel injector dripping or clogging; 6. Partial blockage in the three-way catalytic converter due to carbon buildup or breakage, increasing exhaust resistance; 7. EGR valve opening during engine idle, allowing exhaust gases to enter the combustion chamber. Solutions for high idle speed: 1. Adjust or replace the throttle position sensor; 2. Clean or replace the idle control valve and use a special decoder for basic idle speed setting; 3. Locate the leakage point, reseal or replace related components; 4. Check timing marks and readjust valve timing according to standards.