What are the causes of unstable idle speed and stalling in cars?
2 Answers
The causes of unstable idle speed and stalling in cars include: air intake system leaks, low fuel pressure, clogged air filters, fuel injector atomization leaks, improper idle speed adjustment, faulty spark plugs, and air flow meter malfunctions. Under normal circumstances, the intake air volume must be strictly controlled. If there is a leak in the intake pipe, the air flow sensor cannot accurately measure the actual intake air volume, causing the electronic control unit to inaccurately control the air intake and resulting in unstable idle speed. Fuel injector dripping, clogging, or circuit malfunctions can affect the quantity and quality of fuel injection, preventing it from following the electronic control unit's instructions. This leads to an excessively rich or lean air-fuel mixture, causing poor performance in individual cylinders and unstable idle speed.
I've also encountered issues with unstable car idling or even stalling, let me share the common causes. Unstable idling mostly stems from carbon buildup inside the engine, especially when the throttle body gets dirty and affects air intake, leading to improper air-fuel mixture ratio and causing stalling. Another common point is ignition system failure, such as aging spark plugs or faulty ignition coils - unstable ignition can easily make the idle speed fluctuate. There are also intake system problems, like a clogged air filter preventing proper air intake which affects fuel combustion and causes stalling. Vacuum hose leaks frequently occur too, as old rubber hoses are prone to cracking and air leakage. Finally, don't forget about engine sensors - a faulty crankshaft position sensor causing control inaccuracy can also affect idling. I recommend regular throttle body cleaning and air filter replacement, which can prevent most problems, being both cost-effective and safe.
