How to Replace a Mercury Villager Knock Sensorby Cayden Conor
The knock sensor on the 1993 through 1998 Mercury Villager 3.0-liter engine is located under the intake manifold. It checks for pre-ignition, otherwise known as spark knock. If it senses spark knock, it sends a signal to the programmable control module (PCM), which is the engine's computer. The knock sensor works by sensing the vibrations in the engine, caused by spark knock. The pressure caused by vibrations from spark knock is converted to a voltage signal. This is the signal that the PCM reads. The PCM adjusts the ignition timing and the fuel timing until it does not sense spark knock.
Open the relay box, located near the driver's-side fender well. Read the underside of the cover to determine which relay is the fuel pump relay. Pull the fuel pump relay out of the box using the needle-nose pliers. Crank the engine over three or four times to relieve the fuel pressure. The Villager will not start. Disconnect the negative battery cable using the appropriate wrench.
Place the drain pan under the radiator petcock. Loosen the petcock and allow the antifreeze mixture to drain into the drain pan. If the drain pan is clean, you can reuse the antifreeze mixture, unless the mixture is several years old. If the drain pan is dirty or the antifreeze mixture is several years old, use new antifreeze when you refill the radiator.
Disconnect the air breather tube, the EGR solenoid vent hose and the bypass air inlet hose from the air cleaner-to-intake manifold hose, using the appropriate sockets. Loosen the hose clamps on the air cleaner-to-intake manifold hose clamps, using the appropriate socket, screwdriver or pliers, depending on the type of clamp.
Disconnect the air intake resonator tube from the air cleaner-to-intake manifold hose using the appropriate socket. Pull the air cleaner-to-intake manifold hose off the engine. Disconnect the two electrical connectors on the throttle body, then slide the wiring harness from its bracket. Unclamp and remove the coolant hose from the throttle body. Unplug the EGR solenoid wiring harness connector from the EGR solenoid.
Disconnect the evaporative emission canister vacuum hose from the intake manifold. Disconnect the EVAP canister-to-throttle body hose. Remove the vacuum hose from the fuel pressure regulator to the upper intake manifold.
Mark the spark plug wires, so you know where they go when you put the engine back together. Pull the wires off the spark plugs, then remove the two spark plug wire bracket bolts and the brackets from the upper intake manifold using the appropriate sockets.
Remove the distributor dust cover using the appropriate socket, then loosen the distributor cap screws using a screwdriver. Remove the cap and set it aside (leave the spark plug wires attached to the cap). Disconnect the rear heater valve vacuum hose from the upper intake manifold. Remove both wiring harness bracket bolts and the bracket from the upper intake manifold. Set it out of the way. Disconnect the speed control actuator on the throttle lever, then disconnect the accelerator cable from the throttle lever. If the Villager has a speed control actuator, which would be attached to the bracket, remove it.
Remove the accelerator cable from its bracket on the top of the upper intake manifold. Loosen the locknut on the accelerator cable, then pull the cable out of its bracket on the top of the upper intake manifold. If the Villager has a speed control actuator, loosen the locknut, then remove the actuator from its bracket on the top of the upper intake manifold. Set it aside.
Disconnect the brake booster hose from the power brake booster's check valve. Remove the back pressure transducer valve tube from the EGR valve, then unbolt and remove the EGR valve-to-manifold tube from the EGR valve. Unplug the fast idle control solenoid electrical connector.
Disconnect the engine's wiring harness clips from the breather tube bracket, then remove the two ground wire bolts from the upper intake manifold. Move the ground wires and the harness aside, so that it is not in your way.
Unbolt and remove the two left breather tube bracket bolts from the upper intake manifold. Disconnect the left breather hose from the left valve cover. Remove the bolt from the fuel tube mounting bracket. Loosen the clamp on the coolant hose for the thermostat housing on the upper intake manifold. Unplug the wiring harness connector from the EGR temperature sensor, the connector for the bypass valve, and the idle air control electrical connector. Pull the PCV hose from the upper intake manifold. Remove the five Allen bolts from the upper intake manifold--these bolts hold the upper and lower intake manifold together. Separate the two manifolds, then clean the gasket mating surface of all gasket material.
Unplug the electrical connectors on the six fuel injectors. Pull the right breather hose off the right valve cover. Loosen the clamps on the crossover breather tube and remove the breather tube and the bracket from the upper engine front cover. Unbolt the four fuel injection rail bolts. Move the fuel injector rail and the insulators out of the way. Unplug the engine coolant temperature sensor's wiring harness connector. Unplug the coolant temperature sending unit wiring harness connector.
Loosen the clamps on the upper radiator hose using the appropriate socket, screwdriver or pliers. Pull the radiator hose off the intake manifold. Remove the upper radiator hose bracket using the appropriate socket. Loosen the clamps on the bypass hose on the intake manifold water outlet, then remove the hose. Unbolt and remove the water outlet from the front cover. Remove the heater hose from the top heater core pipe. Using the Allen wrench and the appropriate sequence (see picture in References), remove the lower intake manifold bolts. Remove the four manifold nuts.
Remove the lower intake manifold washers, then lift the intake manifold from the engine. Clean the gasket mating surfaces of all gasket material.
Work the coolant crossover tube back and forth and pull it off the engine. Disconnect the knock sensor's electrical connector. Unbolt and remove the knock sensor using the appropriate socket. Install the new sensor and tighten the bolt firmly. Plug the new sensor's electrical connector in. Reinstall the coolant crossover tube.
Lay the new lower intake manifold gaskets on the cylinder heads, then position the lower intake manifold on the engine. Reinstall the lower intake manifold washers, then install the bolts and nuts. Using the picture in Reference 1, tighten the bolts and nuts in sequence to 30 inch-pounds of torque. On the second go-around, tighten the nuts to 18 foot-pounds of torque, then tighten the bolts to 10 foot-pounds of torque. On the third go-around, tighten the nuts to 18 foot-pounds of torque, then tighten the bolts to 10 foot-pounds of torque, still following the sequence.
Reinstall the components on the lower intake manifold in reverse order of removal. Place the upper intake gaskets on the lower intake manifold, then set the upper intake manifold on the gasket. Tighten the five Allen head bolts to 14 foot-pounds of torque. Reinstall the hoses, plug the sensors in and reinstall the cables on the throttle body. Adjust the cables as necessary. Tighten the radiator petcock. Refill the cooling system. Plug the fuel pump relay in. Connect the negative battery cable. Start the Villager and check for leaks.
Things You'll Need
- Needle-nose pliers
- Drain pan
- Set of sockets
- Set of wrenches
- Allen wrench
- Torque wrench
Cayden Conor has been writing since 1996. She has been published on several websites and in the winter 1996 issue of "QECE." Conor specializes in home and garden, dogs, legal, automotive and business subjects, with years of hands-on experience in these areas. She has an Associate of Science (paralegal) from Manchester Community College and studied computer science, criminology and education at University of Tampa.