Have you noticed that your engine is sounding a little rough or maybe idling high, especially after a wide-open run? There’s no need to panic; the cause may be as simple as a clogged idle air control valve. Although Parker valves may have a slightly different design than other branded idle air control valves, they all basically work the same way.
What does it do?
The idle control valve is a butterfly-shaped air intake port that sits atop the throttle bore of the engine; some models have two air ports and a separate coolant port. These valves control the air flow volume in the engine and are sealed to prevent leakage. Because an extreme amount of air passes through these ports, a condition called cooking can develop.
Cooking has become an issue since the introduction of direct injection (DI) engine. It can cause problems with how the valve operates, leading to erratic operation and even stalling. You may also experience problems without triggering the check engine light. Often the only symptom is high idle speeds and rough motor operation.
The reason for this phenomenon has to do with how DI engines work. With older fuel-injected engines, the fuel passed directly through the intake valve, where petrol treated with detergents keeps the valve clean and free of clogs. With DI engines, the treated fuel never touches the intake valve, so there is nothing to prevent choking. Other benefits of DI engines include fuel delivery of 2,000-3,000 PSI and higher compression ratios, which allows consumers to use lower octane fuel while gaining better economy.
How to Fix It?
Idle speeds cannot be adjusted on contemporary cars and trucks, so cleaning is the only answer. This is a common issue in modern DI engines, and the solution is fairly simple. The first step is preventative maintenance, which means getting the valve checked and cleaned whenever you have your vehicle serviced. You can perform your own tune-ups or have them taken care of at your local garage. When the valves are cleaned, the vacuum lines should also be inspected for cracks or other damage and replaced at the same time.
The best way to ensure that your car runs at peak performance is through regular vehicle maintenance and replacement of wearable parts. All service should be performed on the manufacturer’s recommended schedule for your car’s engine type. This information should be listed in your owner’s manual, in an online specification guide for your make and model year or you can take it to a certified mechanic. Your car gets you where you need to be, so take good care of it for years of optimal functioning.