How to Bypass the Knock Sensor on a 1990 Ford F150by Alibaster Smith
The knock sensor on your 1990 Ford F150 helps to protect the engine from engine knock. Engine knock---or "knocking"---is the result of improper combustion in the combustion chamber of your truck. Usually this is the result of improper timing and ignition. Knocking, if left unchecked, can damage your F150's engine. However, if you are experienced in engine tuning, you can bypass the knocker sensor quite easily.
Disconnect the cable running to the negative battery terminal with a socket wrench. Loosen the nut on the cable clamp and pull the clamp off the negative terminal.
Open the hood and locate the knock sensor. The sensor is located under the engine intake manifold. Normally, it can be reached without removing other components, but it is a tight fit to get your hand underneath there. Make sure the engine is completely cool before reaching down to access the knock sensor.
Squeeze the release tab on the electrical connector running to the knock sensor and pull the knock sensor off. Since the truck will run without the sensor active, this is all that is necessary to bypass the sensor. However, you may wish to remove the sensor if you want to avoid having an unplugged sensor in your engine bay.
Turn the center bolt on the knock sensor counterclockwise to remove and pull the sensor off the engine block. It's a tight fit to remove the center bolt, but it can be done.