CTS 2006-2007, CTS-V 2005-2007, DTS 2006-2007

Mass Air Flow Sensor

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Operation



The Mass Air Flow (MAF) sensor is integrated with the Intake Air Temperature (IAT) sensor. The MAF sensor is an air flow meter that measures the amount of air entering the engine. The Engine Control Module (ECM) uses the MAF sensor signal to provide the correct fuel delivery for all engine speeds and loads. A small quantity of air entering the engine indicates a deceleration or idle condition. A large quantity of air entering the engine indicates an acceleration or high load condition. The MAF/IAT sensor has the following circuits:



An ignition 1 voltage circuit
 
A ground circuit
 
A MAF sensor signal circuit
 
An IAT sensor signal circuit
 
A low reference circuit
 

The ECM applies 5 volts to the MAF sensor on the MAF sensor signal circuit. The sensor uses the voltage to produce a frequency based on the inlet air flow through the sensor bore. The frequency varies within a range of near 1,700 Hertz at idle to near 9,500 Hertz at maximum engine load.

Removal & Installation



2.8L, 3.6L & 4.6L Engines
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Turn the ignition OFF.
  4.  
  5. Remove the Mass Air Flow (MAF) electrical connector.
  6.  
  7. Remove the air cleaner intake duct.
  8.  
  9. Remove the MAF sensor fasteners.
  10.  
  11. Remove the MAF sensor and the MAF sensor seal.
  12.  
  13. Discard the MAF sensor seal.

    Click image to see an enlarged view

    Fig. Mass Air Flow (MAF) Sensor removal

  14.  

To install:

  1. Install the new MAF sensor seal and the MAF sensor.
  2.  
  3. Install the MAF sensor screws.
  4.  
  5. Tighten the MAF sensor screws to 35 inch lbs. (4 Nm).
  6.  
  7. Install the air cleaner intake duct.
  8.  
  9. Install the MAF electrical connector.
  10.  

5.7L & 6.0L Engines
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove the fuel injector sight shield.
  4.  
  5. Disconnect the MAF/IAT sensor electrical connector.
  6.  
  7. Remove the air cleaner outlet duct assembly.
  8.  
  9. Loosen the MAF/IAT clamp.
  10.  
  11. Remove the MAF/IAT sensor from the air cleaner outlet duct. Note the position of the MAF/IAT sensor.
  12.  

To install:

  1. Carefully install the MAF/IAT sensor to the air cleaner outlet duct. Ensure that sensor is clocked properly.
  2.  
  3. Tighten the air cleaner outlet duct clamp.
  4.  
  5. Tighten the air cleaner outlet duct clamp to 27 inch lbs. (3 Nm)
  6.  
  7. Loosely install the air cleaner outlet duct assembly to the vehicle.
  8.  
  9. Connect the MAF/IAT sensor electrical connector.
  10.  
  11. Install the air cleaner outlet duct assembly.
  12.  
  13. Install the fuel injector sight shield.
  14.  

Testing



To determine if the ECM can properly process the MAF sensor frequency signal, connect the J 38522 Variable Signal Generator to the vehicle as follows:

  1. Ignition OFF, connect the battery voltage supply and ground the black lead.
  2.  
  3. Connect the red lead to the signal circuit of the MAF sensor.
  4.  
  5. Set the Duty Cycle switch to Normal.
  6.  
  7. Set the Frequency switch to 5 K.
  8.  
  9. Set the Signal switch to 5 V.
  10.  
  11. Engine running, observe the MAF Sensor parameter for the correct range of 4,950-5,025 Hz.
  12.  
  13. If the MAF Sensor parameter is not within the specified range, replace the ECM.
  14.  
  15. If the MAF Sensor parameter is within the specified range, replace the MAF sensor.
  16.  

 
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