Mazda Trucks 1987-1993 Repair Guide

Air Injection System

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OPERATION



The function of this system is to burn more completely the spent exhaust gases while they are still in the exhaust system. This is accomplished by injecting fresh air into the exhaust port or main converter. the system is comprised of reed valves, air control valves and an Air Control Valve (ACV) solenoid which is controlled by the engine control unit.

SERVICE



Reed Valve
  1. Run the engine until normal operating temperature is reached. Shut off the engine. Remove the air cleaner cover and filter element.
  2.  
  3. Start and run engine at idle speed. Place a piece of paper over the intake ports B and C of the reed valve. Air should be sucked into the valve.
  4.  
  5. Increase speed to 1,500 rpm to verify that air is being sucked in.
  6.  
  7. Increase the engine speed to about 3000 rpm and verify that no exhaust gas is leaking from the air inlet port. Replace the reed valve if not as specified.
  8.  
  9. Disconnect the vacuum line from the No.2 air control valve and plug it.
  10.  
  11. Place a thin piece of paper over inlet port D of the reed valve. Increase the engine speed to about 1500 rpm and verify that air is being pulled in. If not, inspect No. 1 control valve.
  12.  
  13. Disconnect the vacuum line from the No.1 air control valve and plug it.
  14.  
  15. Using a hand vacuum pump apply 3.54 in Hg of vacuum to the No. 2 control valve.
  16.  
  17. Place a thin piece of paper over port E and increase the engine speed to about 1500 rpm. Verify that air is being pulled in. If not as specified, inspect No.2 air control valve and check the reed valve.
  18.  
  19. Turn the ignition switch OFF and disconnect the water temperature switch connector. Start the engine and verify that there is no vacuum at the No. 2 air control vacuum valve hose. Increase the engine speed to 1500 rpm and verify that vacuum is present at the hose.
  20.  
  21. If not as specified, ACV solenoid valve operation should be suspect..
  22.  

Air Control Valve Solenoid

  1. Disconnect the vacuum hoses from solenoid after labeling them for installation reference.
  2.  
  3. Blow air through the solenoid inlet closest to the wire connector and verify that air comes out of the valve air filter.
  4.  
  5. Disconnect the solenoid wire connector and apply battery voltage across the terminals.
  6.  
  7. Blow air through the solenoid inlet closest to the wire connector and verify the air comes out the other vacuum port.
  8.  
  9. If the valve does not operate as specified, replace it.
  10.  

No.1 Air Control Valve

  1. Remove the valve. Connect a vacuum pump to the valve.
  2.  
  3. Blow air into port A and verify that the air does not come out port B .
  4.  
  5. Apply 15.7 in. Hg of vacuum to the valve.
  6.  
  7. Blow air into port A and verify that air does come out port B .
  8.  
  9. If not as specified, replace the valve.
  10.  

No.2 Air Control Valve

  1. Remove the valve. Connect a vacuum pump to the valve.
  2.  
  3. Apply vacuum gradually and verify that the stem of the valve starts to move at approximately 1.97 in. Hg of vacuum and stops at about 3.54 in. Hg vacuum.
  4.  
  5. If not as specified, replace the valve.
  6.  

 
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