Chrysler Front Wheel Drive Cars 4-CYL 1981-1995 Repair Information

Camshaft Position Sensor (CPS)

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OPERATION



Chrysler Multi-Point Fuel Injection (MFI) System

The MFI system is used on 2.2L and 2.5L turbocharged and flex fuel engines.

2.2L TURBO III ENGINE

See Figures 1, 2 and 3



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Fig. Fig. 1: The Camshaft Position Sensor (CPS)-using a new paper spacer during installation is a must



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Fig. Fig. 2: The camshaft gear is equipped with specifically positioned holes, which activate the CPS and inform the PCM of engine timing



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Fig. Fig. 3: The CPS is mounted onto the cylinder head, next to the fuel rail and fuel supply lines

The CPS provides cylinder identification to the PCM. The sensor generates pulses as groups of notches on the camshaft sprocket pass underneath it. The PCM keeps track of the crankshaft rotation and identifies each cylinder by the pulses generated by the notches on the camshaft sprocket. Four crankshaft pulses follow each group of camshaft pulses.

When the PCM receives two camshaft pulses followed by the long flat spot on the camshaft sprocket, it knows that the crankshaft timing marks for cylinder one are next (on the drive plate). When the PCM receives one camshaft pulse after the long flat spot on the sprocket, cylinder No. 2 crankshaft timing marks are next. After three camshaft pulses, the PCM knows cylinder four crankshaft timing marks follow. One camshaft pulse after the three pulses indicates cylinder five. The two camshaft pulses after cylinder No. 5 signals cylinder No. 6. The PCM can synchronize on cylinders No. 1 or No. 4.

When metal aligns with the sensor, voltage goes low (less than 0.5 volts). When a notch aligns with the sensor, voltage spikes high (5.0 volts). As a groups of notches pass under the sensor, the voltage switches from low to high then back to low again. The number of notches determine the amount of pulses. If available, an oscilloscope can display the square wave patterns of each timing event.

Top Dead Center (TDC) does not occur when notches on the camshaft sprocket pass below the sensor. TDC occurs after the camshaft pulse (or pulses) and after the 4 crankshaft pulses associated with the particular cylinder. The arrows and cylinder call in the illustration represent which cylinder the flat spot and notches identify, they do not indicate the TDC position.

The camshaft position sensor is mounted to the top of the timing case cover. The bottom of the sensor is positioned above the camshaft sprocket.

The distance between the bottom of sensor and the camshaft sprocket is critical to the operation of the system.

2.5L ENGINES

The 2.5L engines with MFI utilize distributor reference signals, like the Chrysler EFI system, to keep track of the camshaft and crankshaft positions. The 2.5L Flex Fuel engines do not use separate CPS or CKPS sensors.

TESTING



Chrysler Multi-Point Fuel Injection (MFI) System
2.2L TURBO III ENGINE
  1. With ignition ON and engine OFF , measure voltage between terminals 1 and 2 of the camshaft position sensor harness connector. If the voltage reading is about 8V, the power circuit to the sensor is OK.
  2.  
  3. While varying the engine rpm, measure the voltage between terminals 3 and 2 of the CMP sensor with a DVOM on AC scale (to monitor less than 5.0V). If the reading varies more than 0.1V AC, the sensor is OK.
  4.  

REMOVAL & INSTALLATION

Chrysler Multi-Point Fuel Injection (MFI) System
2.2L TURBO III ENGINE
  1. Disconnect the negative battery cable.
  2.  
  3. Unplug the camshaft position sensor electrical connector from the wiring harness.
  4.  
  5. Loosen the camshaft position sensor retaining bolt enough to allow the slot in the sensor to slide past the bolt.
  6.  
  7. Pull the sensor up and out of the chain case cover. Do not pull on the sensor wires. There is an O-ring on the sensor case and may make the removal slightly difficult. A light tap on the top of the senor prior to removal may reduce the force needed for removal.
  8.  

To install:
  1. If installing the original sensor, clean off the old spacer on the sensor face. A new spacer must be attached to the face before installation. Inspect the O-ring for damage (cuts, tears, etc.), replace with a new O-ring if any damage is found. If the sensor is being replaced with a new one, confirm that the paper spacer is attached to the face and O-ring is positioned in the groove of the new sensor.
  2.  
  3. Apply a couple drops of clean engine oil to the O-ring prior to installation. Install the sensor into the chain case cover and push the sensor down until contact is made with the camshaft gear. While holding the sensor in this position, install and tighten the retaining bolt to 108 inch lbs. (12 Nm).
  4.  
  5. Plug the sensor's connector back into the engine wiring harness. Position the connector away from the accessory drive belt.
  6.  
  7. Connect the negative battery cable.
  8.  

 
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