What Are the Causes of Low Engine Idle Speed?
2 Answers
Engine idling too low can be caused by the following factors: 1. Oil accumulation and carbon deposits in the throttle body, or a dirty intake manifold: As the vehicle ages, the intake manifold may become clogged, and carbon deposits or oil in the throttle body can lead to unstable idling or even low idle speed. 2. Carbon deposits in the throttle body affecting air intake: The vehicle may experience low idle speed during cold starts. It is recommended that owners clean the throttle body and intake manifold to prevent abnormal idling. 3. Weak spark due to faulty spark plugs: Over time, spark plugs can also accumulate carbon deposits. Severe carbon buildup can cause weak sparks in individual cylinders, affecting vehicle performance and resulting in low idle speed. Timely cleaning or replacement of spark plugs is advised.
My old car has been idling extremely low recently, the tachometer almost drops below 500 RPM. It often stalls when I hit the brakes while driving, which really startled me. After checking for a long time, it turned out the throttle body was completely filthy - sludge was blocking the ports, preventing air intake and causing the RPM to stay low. Another possibility is a faulty idle control valve; when that little component fails to regulate RPM accurately, problems arise. Vacuum leaks are also a common cause - aged or cracked tubes under the hood can leak air, destabilizing pressure and lowering idle. The ignition system can be troublesome too - heavily carbon-fouled spark plugs or faulty ignition coils may cause misfires and RPM drops. Don't push your luck with such issues - get to a repair shop immediately for throttle body cleaning or part replacements, safety comes first. Regular maintenance is key - inspect the air filter every six months to avoid roadside breakdowns.
