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S54 Camshaft Sensor Testing
 
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Pelican Technical Article:

S54 Camshaft Sensor Testing

Nick Czerula

Time:

3 hours3 hrs

Tab:

$150

Talent:

****

Tools:

Set of sockets 5mm Allen bit, wrenches, DVOM

Applicable Models:

BMW E46 M3 Coupe/Conv (2001-06)
BMW Z4 Coupe/Conv (2006-08)

Parts Required:

Intake or Exhaust camshaft sensor, sealing O-rings, fasteners, blue Loctite

Hot Tip:

Work with a cool engine

Performance Gain:

Car will run well

Complementary Modification:

Replace sensors in pairs

The digital motor electronics (DME) engine management system in BMW Z4 vehicles with an S54 engine uses the engine control module (ECM) to control fuel injection, ignition and other important drivetrain functions. The ECM sequentially triggers the fuel injectors to spray fuel into the throttle body ports and then, a split-second later, triggers the ignition coils to fire the spark plugs. This sequence of events is timed by using crankshaft position information. Using the signal from the crankshaft sensor, the ECM "knows" which cylinder is ready for fuel intake and then, later, for ignition.

However, in addition to the crankshaft position signal, the ECM needs a signal to distinguish the crankshaft valve-overlap top-dead-center (TDC) position from the TDC just prior to the power stroke. This signal is provided by camshaft position sensors which help synchronize fuel injection and ignition. In addition, camshaft sensors serve as feedback devices for VANOS (variable camshaft timing) control.

When a camshaft sensor fails, the check engine light will illuminate and a fault code will be stored. I have seen faulty sensors cause engine stalling and poor engine drivability. If you have a camshaft sensor fault code and your engine isn't running right, I suggest replacing the sensor before digging too deep. In this article, I'll go over the steps involved with replacing the intake and exhaust camshaft position sensors. The procedures are different, so they will be described separately. BMW suggests replacing the sensor fasteners when removing. This is due to Loctite used at the factory. If you do not want to replace the fasteners, be sure to apply a small amount of blue Loctite on the fastener threads.

Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability.

Vehicle models change and evolve as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

Depending on which camshaft sensor you are replacing, the procedure varies. For intake sensors, the intake manifold has to be removed, along with the fuel injector harness detached. This allows access to the fastener and wiring harness. Exhaust sensors can be accessed or removed simply by removing the engine cover to make room for the wiring harness to move around.

On Z4 models with a S54 6-cylinder engine, the intake (inlet) camshaft sensor is located behind the cylinder head on the left side of the engine (red arrow).
Figure 1

On Z4 models with a S54 6-cylinder engine, the intake (inlet) camshaft sensor is located behind the cylinder head on the left side of the engine (red arrow). The exhaust (outlet) camshaft sensor is located at the right rear of the cylinder head (green arrow). See our tech article on camshaft sensor replacing for accessing the sensors.

Locate the sensor with the fault code.
Figure 2

Locate the sensor with the fault code. In our case, a fault showed up with the exhaust sensor. Terminal 1 is the sensor supply voltage (red arrow). Terminal 2 is the sensor reference voltage / signal wire (yellow arrow). Terminal 3 is the ground for the sensor provided by the DME (brown arrow). The wiring color and DME terminal locations may vary. Check your model against a wiring diagram. Turn the Key ON, but do not start the engine. Connect your DVOM black lead to battery negative. Place the DVOM on D/C volts. The red lead will be used to probe the electrical connector. Pin 1: 12 (battery) volts. Pin 2, sensor signal, zero or 5 volts. Pin 3 Ground, around zero volts.

It doesn't matter where you start testing, as long you test all the wires.
Figure 3

It doesn't matter where you start testing, as long you test all the wires. Here I began with the supply voltage (red arrow) on Pin 1.

Then I moved to the reference (signal) voltage on Pin 2.
Figure 4

Then I moved to the reference (signal) voltage on Pin 2. If this is tested with the sensor plugged in, it could read zero, if the sensor is excited. By lifting and lowering the sensor once it was unbolted, voltage should be about 5 volts. This shows the Hall-effect switch if the sensor is functioning and it is creating a good signal. Once you test the three sensor voltages, next rotate the engine by hand to see if the sensor is producing a signal.

Finally, terminal 3, ground.
Figure 5

Finally, terminal 3, ground.

Raise and support your vehicle.
Figure 6

Raise and support your vehicle. Rotate the engine clockwise by hand using a 32mm socket (or the BMW crankshaft rotating socket) and ratchet (red arrow) on the crankshaft pulley bolt. Backprobe the connector at terminal 2. Monitor the DVOM for voltage to fluctuate from 5 volts to zero volts as the engine rotates. If voltage stays at 5 volts or 0 volts while you rotate the engine, and does not fluctuate, the sensor is faulty.

Testing with sensor removed: You can also test the sensor with it removed from the engine.
Figure 7

Testing with sensor removed: You can also test the sensor with it removed from the engine. Turn the Key ON, but do not start the engine. Remove the sensor from the engine. See our tech article on camshaft sensor replacing. Connect your DVOM black lead to battery negative and place the DVOM on D/C volts. The red lead will be used to probe the electrical connector. Connect the camshaft position sensor electrical connector. Insert a backprobe into terminal 2. Then connect the red lead of your DVOM to backprobe. Hold the sensor while moving a wrench across the tip. Monitor the DVOM. The voltage should fluctuate just as it should when rotating the engine by hand. In this photo the wrench (blue arrow) is away from the sensor (red arrow), so the DVOM reads 5 volts. When the wrench (yellow arrow) is close to the sensor (red arrow), so the DVOM reads 0 volts.

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Page last updated: Sat 12/3/2016 03:08:45 AM