Idle Speed

While the engine is cold, the Idle Speed Control By-Pass Air (ISC-BPA) valve increases idle speed to warm the engine quickly. At engine temperatures less than 140°F (60°C), the valve is open. As the engine warms, the valve begins to close. The valve is fully closed at engine temperatures greater than 140°F (60°C). Idle speed is also affected by various switches, sensors, and load on the engine.