Hardlymoving writes about do-it-yourself automobile maintenance on various makes and models.
Rough and shaky engine idle? Uneven and jerky engine acceleration? Could be excessive carbon buildup on your throttle body's throttle plate and idle air control valve.
This article, via video, will show you how to clean the throttle body and idle air control valve on Toyota's 5SFE engine.
Toyota's robust 4 cylinder 5SFE engines, deployed in the millions over ten years in various model vehicles, are still chugging around the world. If you own a vehicle with one of these engines, cleaning the throttle body every 50,000 miles or so will keep you engine running smooth for years on end.
The main component of the throttle body that accumulates carbon buildup is the throttle plate. The accumulation is caused by a combination of EGR (exhaust gas recirculation) fumes combined with PCV (positive crankcase ventilation) oily blow-by gases backing up against the throttle plate. Excessive carbon accumulation can prevent the even flow of filtered air past the throttle plate as well as hamper the movement of the throttle plate itself, which is controlled by the throttle cable and the throttle body's throttle plate spring.
Smooth engine idle is also controlled by the IAC (idle air control valve). The IAC behaves like a mini-throttle body or "choke" controlling the minute amounts of air that enters the engine's intake during a cold engine's start and warmup. When the IAC becomes gummed up with excessive carbon, the stuck IAC valve may make the engine idle run too high at normal engine temperatures or too low when the engine is warm. On the 5SFE engine, the IAC is attached to the bottom of the throttle body.
Video: Cleaning the Toyota 5SFE Engine Throttle Body and Idle Air Control Valve
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
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