The crankshaft position sensor (CKP sensor M50)

The crankshaft position sensor (CKP sensor M50)On fuel injected engines are equipped with a management system Motronic one of the most important elements is the crankshaft position sensor (CKP sensor). It can answer for what the engine will start to fall at a certain speed from time to time. But don't despair. For such behavior may respond to a bunch of different other sensors or problems: sensor mass air flow (MAF), spark plugs, high voltage wire, very bad gasoline or a lot of things different. But now let's talk about CKP sensor, as in the case of problems it is necessary to check first.

Camshaft position sensor symptoms

Failure CKP sensor does not always correctly interpreted by the control system and can be adopted for the error of the camshaft position sensor (DCV) or for the error of the flow meter (MAF) or other systems. The sensor readings are used to determine the rotational speed of the engine, the relay of the fuel pump, ignition control and fuel injection. Thus the result of a refusal or false sensor reading will be interruptions in the systems of fuel injection and ignition.

The crankshaft position sensor (CKP sensor M50)

In practice (in one case) floating CKP sensor failure led to the following problems:
  • Difficulty starting the engine (takes about 10 attempts).
  • Unstable idling, the engine was regularly stalling when going into idle mode.
  • Unstable operation at low and medium engine speeds, while in those moments when the reading sensor reads fine, but mostly it happened at high rpm, the engine runs in normal mode, the maximum speed and acceleration dynamics remained almost normal
  • Strange rpm readings when engine braking, for example when driving downhill - rpm arrow "jump" from 2500 rpm up to 2000 and back, thus changing the speed felt, but not as significant, it is most likely that the jerks due to a complete disconnection of fuel supply in moments of failure of the sensor, and tachometer readings - a consequence of false sensor readings.

Testing CKP sensor:

To check CKP sensor you need to remove the chip connector and measure the resistance between pin 1 and pin 2, which should be 1280 Ohms +-10% (see figure). Hand sensor Bosch you can check any metal object like a screwdriver. Defective sensor well enough magnets.

Replacement CKP sensor

On the M50 motor CKP sensor is located at the front of the engine and detects the passage of teeth of the crankshaft pulley (see photo). For easy access to the sensor, it is necessary to remove the impeller or the right inlet of the cooler (after draining the coolant). Before installing the new sensor, it is desirable to strip the site for the correct positioning of the sensor is the gap between the sensor and the teeth of the pulley should be 1 +-0.3 mm.

On the M50 engine fit some models CKP sensor by Bosch which cost several times less. The only drawback is the slightly shorter length of wire, which, however does not prevent its use.

Position sensor engine crankshaft (CKP sensor) – induction type, is a coil with a magnetic core, the winding resistance is 880-900 Ohms. For normal operation of the control system it is necessary that the clearance between the sensor and the teeth of the disk was 0.5 – 1.0 mm. the sensor Cable must be firmly secured to prevent damage to the rotating parts of the engine and generator. At malfunction CKP sensor operation of the engine impossible.