Why is the car idling low?
2 Answers
The reasons for low car idle speed are: 1. Uneven fuel injection quantity or poor atomization from the injectors, causing an imbalance in power output among cylinders, resulting in unstable idle speed when the engine is cold. 2. Fuel pressure is too low, leading to poor atomization or linear fuel spray from the injectors, and in severe cases, only fuel droplets are sprayed. Reduced fuel injection quantity makes the air-fuel mixture too lean, causing unstable idle speed when the engine is cold. 3. Temperature sensors, oxygen sensors, or their circuits fail to respond promptly, causing the control unit to issue incorrect commands. This results in incorrect fuel injection quantity, making the air-fuel mixture too rich or too lean, leading to unstable idle speed when the engine is cold.
Idle speed too low? I've encountered this issue several times, and it seems quite common. Usually, it's caused by a dirty throttle body or sludge buildup, restricting air intake into the engine and causing unstable RPM. A faulty mass airflow sensor can also mislead the ECU into incorrectly reducing idle speed. Additionally, leaks in the intake system, such as vacuum hoses, can draw in excess air and lower the RPM. Worn spark plugs or ignition system failures affecting combustion efficiency are also contributing factors. When I handle this myself, I first check the throttle body and give it a quick clean with carburetor cleaner. If that doesn’t help, I’ll inspect sensor voltages or oxygen sensor signals. Low idle speed doesn’t just affect engine smoothness—it can increase fuel consumption or even lead to stalling, posing safety risks. Regular maintenance, like cleaning the throttle body every 10,000 km, helps prevent it. If you notice abnormalities, don’t delay—address them early for peace of mind and safety.
