What Causes Unstable Idle Speed After a Major Overhaul of the Ford Kuga?

[Noelle]

This situation is most commonly caused by excessive carbon buildup inside the throttle body. The idle speed control valve fails to regulate the idle properly. Take the vehicle to a repair shop and have a technician clean the throttle body and idle speed control valve. Below are the reasons for low idle speed: Throttle Body Carbon Buildup: As the vehicle ages, the intake passages can become clogged. Carbon deposits or oil inside the throttle body can lead to unstable idle speed or even low idle. Spark Plug Carbon Buildup: Over time, carbon can also accumulate on the spark plugs. Severe carbon buildup can weaken the spark on some cylinders, affecting vehicle performance and causing low idle speed. Clogged Fuel Injectors: When the fuel injectors become clogged, the fuel supply pressure and atomization deteriorate, resulting in unstable or low idle speed.