How to Diagnose and Troubleshoot Unstable Engine Idle?
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Methods for diagnosing and troubleshooting unstable engine idle include: 1. Check for air leaks in the intake pipe, PVC valve hose, and oil dipstick area; 2. Inspect whether the air filter element is excessively dirty; 3. Verify the proper functioning of the cold start injector and temperature-time control switch; 4. Check if the fuel system pressure is too low; 5. Examine the injector spray pattern; 6. Inspect cylinder pressure and valve clearance; 7. Check the ECU. When the engine operates normally at medium to high speeds but exhibits unstable idle or even stalls at idle or near-idle speeds, this indicates an idle malfunction.