Symptoms

- Engine Light ON (or Service Engine Soon Warning Light) - Engine hard to start - Rough or erratic idle speed

Possible Causes

- Dirty throttle body - Electric throttle control actuator misadjusted or damaged - Faulty Electric throttle control actuator - Intake air leak - Poor electrical connection to the Intake Air Control (IAC) valve

When Detected

The idle speed is less than the target idle speed by 100 rpm or more.

Tech Notes

There is a service bulletin for Ford vehicles: 2004-2006 Ford F-150 P0506 Ford Service Bulletin Ford: 2005-2007 Ford Crown Victoria 2006 Ford Mustang, Mustang 2004-2006 Ford F-150 2005-2006 Ford E-350, Ford E-450, Ford F-Super Duty 2006-2007 Ford Explorer Sport Trac, Ford Explorer LINCOLN: 2005-2007 Town Car 2006 Mark LT MERCURY: 2005-2007 Grand Marquis 2006-2007 Mountaineer P0505/P0506 Ford Service Bulletin

Description

The ECM controls the engine idle speed to a specified level through the fine adjustment of the air, which is let into the intake manifold, by operating the electric throttle control actuator. The operating of the throttle valve is varied to allow for optimum control of the engine idling speed. The ECM calculates the actual engine speed from signals of crankshaft position sensor (POS) and camshaft position sensor. The ECM controls the electric throttle control actuator so that the engine speed coincides with the target value memorized in the ECM. The target engine speed is the lowest speed at which the engine can operate steadily. The optimum value stored in the ECM is determined by taking into consideration various engine conditions, such as during warming up, deceleration, and engine load (air conditioner, power steering and cooling fan operation, etc.)