How to Put a Crankshaft Sensor on a 1994 Mercury Tracer

The 1999 Mercury Tracer came in two trim levels: base and LTS. The base model came with an 88-horsepower, 1.9-liter four-cylinder engine, and the LTS came with a 127-horsepower, 1.8-liter engine. Both engines utilized a crankshaft position sensor to aid the vehicle's computer in calculating the engine speed and timing the other electrical components of the engine. The 1.9-liter engine used a standalone crankshaft position sensor that sat above the crankshaft pulley. The 1.8-liter's crankshaft position sensor was part of the distributor assembly. Replacing the 1.8-liter's crankshaft position sensor requires replacing the distributor and adjusting the ignition timing.

Instructions

Replacing a Crankshaft Position Sensor on a 1.9-Liter Engine

1

Loosen the negative battery cable, using a combination wrench, and pull it from the battery. Position the cable away from the battery to prevent accidental connection.

2

Loosen, but don't remove, the passenger-side front wheel lug nuts, using a ratchet and socket. Raise the front of the Tracer, using a floor jack, and position jack stands under the Mercury's subframe. Lower the Tracer onto the jack stands. Remove the lug nuts and pull the wheel from the vehicle.

3

Remove the bolts securing the splash guard inside the wheel well, using a ratchet and socket, and pull the splash guard from the Tracer.

4

Locate the crankshaft position senor at roughly the 11 o'clock position relative to the crankshaft pulley. Unplug the crankshaft position sensor wiring harness by lifting up on the locking tab and pulling the harness from the sensor.

5

Remove the crankshaft position sensor bolts, using a ratchet and socket, and pull the sensor from the engine.

6

Set the new crankshaft position sensor on the engine and tighten its bolts to 3 to 5 foot-pounds, using a torque wrench and socket. Plug the wiring harness into the sensor.

7

Reinstall the wheel well splash guard and tighten its bolts with a ratchet and socket. Install the front wheel and hand-tighten the lug nuts.

8

Raise the Tracer from the jack stands, using a floor jack, and pull the stands from under the Mercury. Lower the vehicle to the ground. Apply 90 foot-pounds of torque to the lug nuts, in a crisscross pattern, using a torque wrench and socket.

9

Reconnect the negative battery cable and tighten it to 11 foot-pounds, using a torque wrench and socket.

Replacing a Crankshaft Position Sensor on a 1.8-Liter Engine

10

Loosen the negative battery cable, using a combination wrench, and pull it from the battery. Position the cable away from the battery to prevent accidental contact.

11

Remove the coil wire -- the center wire -- from the distributor cap, by pulling upward with a slight twisting motion. Loosen the two distributor cap screws, using a Phillips screwdriver, and pull the distributor cap from the distributor unit. Replace the distributor cap, if needed, by transferring the spark plug wires to a new cap. Transfer the wires one at a time to retain the correct firing order.

12

Create a match mark on the ignition rotor, using white marking paint. Make another match mark on the distributor housing, in line with the mark on the rotor. Pull the distributor rotor from the distributor assembly. Inspect the rotor for any burning or significant aging and replace it as needed.

13

Matchmark the distributor to the cylinder head, with the white marking paint. This creates a general reference point for installing the new distributor. Unplug the wiring harness from the distributor by pulling up on the locking tabs and pulling the harness from the distributor.

14

Remove the distributor-to-cylinder head mounting bolts, using a ratchet and socket, and pull the distributor from the cylinder head. Do not disturb the engine in any way after removing the distributor.

15

Set the old distributor next to the new one and make a match mark on the new distributor in approximately the same areas as the match marks on the old distributor. You cannot be exact here, but this will get the initial ignition timing close.

16

Install a new O-ring -- included with the distributor -- on the new distributor, if not installed already. Set the O-ring on the engine side on the distributor and roll it toward the top of the distributor until it seats in the groove.

17

Install the new distributor on the cylinder head, making certain the tabs on the engine side of the distributor insert into the slots in the cylinder head. Do not force the distributor in place; it slides in easily when positioned correctly.

18

Rotate the distributor until the match mark on it lines up with the match mark on the cylinder head. Tighten the distributor bolts to 14 to 19 foot-pounds, using a torque wrench and socket. Plug the wiring harness into the distributor.

19

Press the rotor onto the distributor in a position where the match mark on the rotor points toward the match mark on the distributor housing. Set the distributor cap on the distributor and tighten the screws, using a Phillips screwdriver. Press the coil wire onto the center receptacle on the cap; feel for it to "click" into place.

20

Reconnect the negative battery cable and tighten it to 11 foot-pounds, using a torque wrench and socket. Proceed to the section titled "Checking and Adjusting the Timing on a 1.8-Liter Engine" to check and adjust the timing, as needed.

Checking and Adjusting the Timing on a 1.8-Liter Engine

21

Locate the yellow timing mark on the crankshaft pulley and the timing reference tab just above the crankshaft pulley. Clean both of these components, using parts cleaner and a shop cloth.

22

Place the Mercury in "Park" or "Neutral" and engage the vehicle's parking brake. Start the engine and allow it to reach operating temperature. Turn off all unnecessary loads, such as: headlights, radio, air conditioning, turn signals and windshield wipers.

23

Connect a timing light to the Mercury. The exact instructions vary, depending on the light, so refer to the timing light's instruction manual for specific directions.

24

Locate the diagnostic link connector just behind the Mercury's battery (see resources). Open the DLC lid by pressing the locking tab and pulling the lid upward.

25

Insert a jumper wire between the ground terminal and terminal 10 on the DLC (see resources for diagram).

26

Connect the "Input" or positive wire on a tachometer to the "IG" terminal in the DLC (see resources for diagram) and connect the "Ground" wire to the negative battery terminal.

27

Aim the timing light at the timing reference tab above the crankshaft pulley and pull the trigger. Each time the light flashes check where the yellow timing mark on the crankshaft is relative to the timing reference tab (see resources). At 700 to 800 rpm, the timing mark should be at 10 degrees before top dead center.

28

Loosen the distributor mounting bolts, using a ratchet and socket, and turn the distributor to adjust the timing until it meets the specification listed in Step 7.

29

Tighten the distributor mounting bolts to 14 to 19 foot-pounds, using a torque wrench and socket, once you correctly set the engine's timing.

30

Remove the jumper wire and tachometer wire from the DLC and close the DLC lid. Remove the timing light and disconnect the tachometer ground. Close the Mercury's hood.