What are the symptoms of a bad throttle body?
2 Answers
The symptoms of a bad throttle body include: 1. Unstable engine idle speed, high idle speed that does not drop, and difficulty starting the engine; 2. Unstable engine idle speed or no idle speed; 3. Insufficient engine power, poor acceleration performance, and unstable operation; 4. Black smoke from the car's exhaust pipe. The throttle body is a controllable valve that regulates the air entering the engine. After the air enters the intake pipe, it mixes with gasoline to form a combustible mixture, which then burns to create power. It connects to the air filter at the top and the engine block at the bottom, and is known as the throat of the car engine. There are two types of throttle bodies: traditional cable-operated and electronic. The traditional engine throttle body operates through a cable (soft steel wire) or rod, with one end connected to the accelerator pedal and the other end connected to the throttle linkage plate.
Having driven for over a decade, the most obvious sign of a faulty throttle body is unstable idling. When waiting at a red light, the tachometer needle jumps up and down erratically, like having a fever, and the steering wheel shakes along with it. Pressing the accelerator hard actually feels weak, as if the engine is struggling to breathe. If you accelerate sharply, black smoke may even puff out from the rear. Once on the highway, my engine warning light suddenly came on, and the idle speed dropped straight to 500 RPM, nearly stalling—scared me enough to pull over immediately. The mechanic said these symptoms are 80% likely a stuck throttle body, either from excessive carbon buildup or a jammed throttle plate. Regular cleaning can prevent it, but if it's truly broken, replacement is the only fix.
