What are the reasons for low car idle speed?
2 Answers
The reasons for low car idle speed are: 1. Oil accumulation or carbon buildup in the throttle valve; 2. Dirty intake manifold; 3. Weak spark due to faulty spark plugs; 4. Malfunctioning idle control valve; 5. Poor atomization or clogging of the fuel injector; 6. Changes in oil viscosity. The solutions for low car idle speed are: 1. Check for oil accumulation or carbon buildup in the throttle valve; 2. Clean the intake manifold; 3. Inspect the working condition of the spark plugs; 4. Check if the idle control valve is malfunctioning; 5. Examine the fuel injector for any issues; 6. Replace the engine oil promptly. The reasons for high car idle speed are: 1. Idle switch not closing; 2. Faulty idle control valve; 3. Air leakage in the intake pipe; 4. Incorrect valve timing; 5. Fuel injector dripping or clogging; 6. Blocked exhaust system; 7. EGR valve opening during idle conditions.
Low idle speed is one of the most annoying issues I've encountered while driving. My car used to have this problem too, with RPM consistently dropping below 700, causing severe engine vibration. The main causes are: first, carbon buildup or sticking in the idle control valve, preventing air from entering the engine; aging vacuum hoses with leaks are common – cracks in the tubing allow excess air to seep in; dirty or faulty sensors like the throttle position sensor can cause the ECU to miscalculate fuel injection; ignition system issues such as worn spark plugs or unstable ignition coils may fail to ignite the fuel; fuel system problems like clogged fuel injectors result in insufficient fuel delivery, naturally lowering RPM. If left unrepaired, low idle speed can lead to stalling and engine damage. I recommend first checking simple fixes like cleaning the idle valve, and if that doesn't work, take it to a repair shop to read fault codes with a diagnostic tool – don't let the problem escalate. Regularly replacing air filters and spark plugs can prevent such faults.
