Attention! Disconnecting and removing the ignition system sensors can cause damage that will be recorded in the memory of the electronic control unit. Some faults stored in the memory may cause the system to switch to a special mode of operation, which may affect the mode of operation of the ignition system. It is advisable to contact a service station after any repair of the ignition system in order to erase the recorded damage from the memory of the electronic unit.
Crankshaft speed sensor
Removing
1. Remove the ground wire from the battery.
2. Disconnect the electrical connector from the crankshaft speed sensor located in the engine compartment behind the battery.
3. On models with HFM engine management, remove the starter from the clutch housing to improve access to the sensor.
4. Unscrew the bolt and remove the sensor from the clutch housing. Remove the gasket.
Installation
1. The crankshaft speed sensor is installed in the reverse order of removal.
Camshaft position sensor
Removing
Location of the camshaft position sensor
1. The camshaft position sensor is located at the front of the cylinder head to the left of the drive chain sprocket cover (see fig. Location of the camshaft position sensor). Check that the ignition is off and disconnect the electrical connector from the camshaft position sensor.
2. Remove the screws and remove the camshaft position sensor.
3. Remove the O-ring and shims.
Installation
1. Installation is made in sequence, return to removal. If necessary, install a new O-ring and shims of the required thickness.
Attention! The shims determine the distance from the sensor to the lip on the camshaft sprocket that controls the intake valves. If the thickness of the shims is less than acceptable, then the protrusion on the camshaft sprocket may hit the camshaft position sensor. To check the clearance, remove the cylinder head cover, then rotate the engine until the projection on the camshaft sprocket is aligned with the camshaft position sensor. Using a feeler blade, check that the clearance between the camshaft sprocket lug and the camshaft position sensor is 0.4 - 0.6 mm. If necessary, adjust the clearance by changing the thickness of the shims under the camshaft position sensor.
Knock sensors
Removing
1. Knock sensors are installed on the left side of the engine block. Since the sensors share a common wiring harness, they can only be removed as an assembly.
2. Check that the ignition is OFF and disconnect the knock sensor harness electrical connector from the control unit.
3. Remove the knock sensor wiring harness from the mounting brackets. On models with HFM engine management, remove the starter to improve access.
4. Unscrew the mounting bolts and remove the knock sensors from the cylinder block.
Installation
1. Installation is made in sequence, return to removal. Tighten the knock sensor mounting bolts to the required torque.
Electronic control device
EZL ignition system
Removing
The location of the electronic control device ECU control the ignition system EZL
1. The electronic control device of the ignition control system is installed on the left side of the engine compartment on the top of the wheel arch (see fig. The location of the electronic control device ECU control the ignition system EZL).
2. Remove the ground wire from the battery.
3. Disconnect the electrical connectors for the crankshaft position sensor and knock sensor. Label and disconnect the two multi-pin connectors from the electronic control device.
4. Disconnect the intake manifold vacuum hose from the electronic control device and close the hole with a plug.
5. Unscrew the nuts and remove the electronic control device from the engine compartment.
Attention! To improve heat dissipation from the electronic control device, its lower surface is covered with a special heat-conducting paste.
Installation
1. Installation is made in sequence, return to removal. If the thermal paste layer is dirty or hardened, purchase fresh paste from your Mercedes-Benz dealer and replace it.
HFM engine management system
See relevant information in subsection 11.12.
Coolant temperature sensor
Location of coolant temperature sensor
Typically, the ignition system and the fuel injection system have one common coolant temperature sensor.
Throttle limit switch
The ignition system and the fuel injection system are controlled by one common throttle limit switch. The throttle position switch can only be removed with the throttle body removed. The switch must only be installed at a service station.
Intake air temperature sensor
Removing
1. The air intake temperature sensor is located on the side of the air filter housing.
2. Check that the ignition is off, then disconnect the electrical connector from the sensor.
3. Turn the sensor a quarter of a turn and remove it from the air filter housing. Remove the gasket.
Installation
1. Installation is made in sequence, return to removal.
Top dead center sensor
The TDC sensor is mounted on a bracket above the vibration damper on the front side of the engine. The position of the top dead center sensor is very important for setting the ignition timing, so the replacement of the top dead center sensor must be done at a service station.