
A faulty throttle body can cause the following problems in a car: unstable engine idle speed, persistently high idle speed, difficulty in engine starting, unstable engine idle speed, and no idle speed. The throttle body is a controllable valve that regulates the air entering the engine. After the air enters the intake manifold, it mixes with gasoline to form a combustible mixture, which burns to produce power. It is connected to the air filter at the top and the engine block at the bottom, and is referred to as the throat of the car engine. There are two types of throttle bodies: the traditional cable-operated type and the electronic throttle body. In traditional engines, the throttle body operates through a cable or linkage, with one end connected to the accelerator pedal and the other to the throttle linkage plate. The electronic throttle body primarily uses a throttle position sensor to control the throttle opening angle based on the engine's required power, thereby regulating the amount of air intake.

Last time my friend's car had a throttle body failure, it was quite troublesome. The most obvious symptom was the tachometer needle jumping erratically at idle, with the car body shaking like a phone on vibrate mode. Accelerating required extra effort on the gas pedal, feeling like someone was holding the car back. Cold starts needed keeping the throttle pressed to fire up, and fuel consumption suddenly increased by 20-30%. Even more annoying was the constant engine warning light and the transmission acting up during gear shifts. These issues ultimately stem from uncontrolled air intake, confusing the ECU about proper fuel delivery. If this happens on highways, it's extremely dangerous - I'd recommend calling roadside assistance for towing to a professional repair shop immediately.

My old car had throttle body issues last year. It was particularly difficult to start in the morning, requiring multiple ignition attempts. At red lights, the shaking was so severe that the rearview mirror vibrated, and the steering wheel trembled too. On the highway, acceleration was sluggish, requiring triple the usual distance for overtaking. The engine warning light on the dashboard kept illuminating, and fuel consumption was absurdly high, burning an extra 4 liters per 100 kilometers. The mechanic later explained that the throttle plate was stuck, causing insufficient air intake and throwing the ECU programming into chaos. Such faults should never be neglected, as they can cause collateral damage to the oxygen sensor and catalytic converter, leading to even costlier repairs.

Throttle failure manifests quite noticeably. At idle, the vehicle exhibits abnormal shaking with fluctuating RPMs. During driving, pressing the accelerator results in sluggish power output, akin to having the exhaust pipe blocked. Cold starts become difficult, requiring simultaneous throttle input to ignite. Fuel consumption spikes noticeably in the short term, with the engine warning light remaining illuminated on the dashboard. These symptoms stem from the throttle's inability to precisely regulate air intake, compromising air-fuel mixture accuracy. In severe cases, it may even cause jerky automatic transmission shifts and engine overheating leading to protective shutdown. Immediate inspection is recommended upon observing two or more symptoms.

When the throttle body fails, the vehicle may experience a series of interconnected issues. Initially, the idle becomes unstable, with noticeable vibrations in the steering wheel and seats. Subsequently, acceleration performance deteriorates, especially when climbing hills, where power loss is severe. Fuel consumption increases significantly, leading to a sharp drop in driving range. Cold starts may require continuous ignition for seven to eight seconds before the engine fires up. More troublesome is that after the malfunction indicator light comes on, some electronic assistance systems may become restricted. These problems all stem from a faulty throttle position sensor or a stuck throttle valve. It is recommended to clean the throttle body as soon as possible. Also, remember to check the intake manifold's sealing, otherwise, the cleaning effect may be compromised.


