Q: How to serve the knock sensor in the Ford Excursion?
A: The 2005 and 2006 models use two knock sensors. The service procedure is the same. The knock sensor is located under the intake manifold. The knock control system is designed to reduce spark knock during periods of heavy detonation. This allows the engine to use optimal spark advance to improve driveability. The knock sensor detects abnormal vibration in the engine and produces a voltage output that increases with the severity of the knock. The voltage signal is monitored by the PCM, which retards ignition timing until the detonation ceases. A problem in the knock sensor circuit will set a diagnostic trouble code. Make sure the ignition key is in the OFF position. Drain the cooling system. Remove the intake manifold. Disconnect the electrical connector and remove the knock sensor. If you're going to reuse the old sensor, coat the threads with thread sealant. New sensors are pre-coated with thread sealant; do not apply any additional sealant or the operation of the sensor may be affected. Install the knock sensor and tighten it securely. Don't overtighten the sensor or damage may occur. Plug in the electrical connector, refill the cooling system, and check for leaks. Installation is the reverse of removal.