Acura Coupes and Sedans 1986-1993 Repair Guide

Exhaust Gas Recirculation (EGR) System

Print

The EGR valve is not simply open or closed but is modulated by controlling the amount of engine vacuum to the valve diaphragm, up to a maximum of 8 in. Hg of vacuum. The EGR valve has a sensor in the top of the valve that reports valve lift to the ECU. The ECU modulates the position of the control solenoid valve to control the EGR valve lift according to an internal program.

TESTING



If the red self-diagnosis LED indicator blinks 12 times, indicating trouble Code 12, there is most likely a problem in the EGR system.

Integra

See Figure 1



Click image to see an enlarged view

Fig. Fig. 1: EGR system-Integra

  1. If trouble Code 12 flashes or the Check Engine light has come on, check that all of the connectors between the EGR valve sensor and the PGM-FI ECU are secure.
  2.  
  3. Warm the engine to normal operating temperature or until the cooling fan comes on.
  4.  
  5. Disconnect the No. 16 hose from the EGR valve.
  6.  
  7. Connect a vacuum pump to the disconnected hose and apply vacuum. If there is vacuum, proceed to Step a. If there is no vacuum, skip to Step 5.
    1. Disconnect the 4-pin connector from the control box and again check the No. 16 hose for vacuum.
    2.  
    3. If vacuum is present, check EGR system vacuum hose routing. If hose routing checks out OK, replace the EGR control solenoid valve.
    4.  
    5. If vacuum is not present, inspect for a short or opening in the Red wire between the ECU and the EGR control solenoid valve. If the wire checks out OK, replace the ECU with a known-good unit and retest.
    6.  

  8.  
  9. Move the vacuum pump/gauge to the EGR valve and apply 8 in. Hg of vacuum to the EGR valve. If the engine does not stall and the EGR valve does not hold vacuum, replace the EGR valve.
  10.  
  11. If the engine stalls and the EGR holds vacuum, disconnect the 4-pin connector from the control box and measure the voltage between the Black/Yellow (+) terminal on the main wire harness and the body ground.
  12.  
  13. If voltage is not present, check for a short in the wiring in Black/Yellow wire between the solenoid valve and the No. 24 fuse. If there is voltage present, reconnect the vacuum hose No. 16 to the vacuum pump/gauge and start the engine and allow it to idle.
  14.  
  15. Connect the positive battery terminal to the B terminal of the 4 pin connector and connect the negative battery terminal to the D terminal. Watch the vacuum gauge. There should be approximately 6 in. Hg of vacuum within 1 second. If there is the specified amount, skip to Step 9 and if not, proceed to Step a.
    1. Turn the ignition switch OFF and inspect the No. 16 and No. 20 hoses for leaks, restrictions or misrouting.
    2.  
    3. If the hoses check to be OK, check the EGR control solenoid valve by connecting a vacuum gauge to the lower hose. Start the engine and allow it to idle and check the amount of vacuum present.
    4.  
    5. If there is not approximately 8 in. Hg of vacuum present, replace the CVC valve. If there is approximately 8 in. Hg of vacuum present, replace the EGR control solenoid valve.
    6.  

  16.  
  17. Turn the ignition switch OFF and reconnect the 4-pin connector. Connect the test harness between the EGR valve lift sensor and the engine wire harness. Turn the ignition switch ON and measure the voltage between the Red (+) and Green (-) terminals. If there is not approximately 5 volts, check for a short in the Yellow/White or the Green wiring between the EGR valve and the ECU.
  18.  
  19. If there is approximately 5 volts present, measure the voltage between the White (+) and Green (-) terminal. There should be approximately 1.2 volts. If prescribed voltage is not present, replace the EGR valve, check for short in Green/Red wire between the ECU and the EGR valve lift sensor and substitute a known-good ECU and recheck.
  20.  
  21. Apply 8 in. Hg of vacuum to the EGR valve and watch the voltmeter. Repeat this several times, making sure to completely release all vacuum in between steps. Measure the voltage between the White (+) and Green (-) terminals. The voltage should be approximately 4 volts. If the voltage is not correct, replace the EGR valve.
  22.  
  23. If the voltage is correct, watch the voltage as vacuum increases and decreases. Voltage should consistently increase and decrease also. If it does not, replace the EGR valve. If it does increase and decrease consistently, reconnect the No. 16 hose to the EGR valve.
  24.  
  25. Turn the ignition switch OFF and connect the PGM-FI test harness between the ECU and the connector. Start the engine and allow it to idle.
  26.  
  27. Measure the voltage between the C8 (+) and the C12 (-) terminals, there should be approximately 1.2 volts present. If voltage is not present, repair the open or short in the Green/Red wire between the ECU (C8) terminal and the sensor.
  28.  
  29. If the voltage is present, connect the A8 terminal to the A18 terminal with a jumper wire. If the engine does not stall or run rough, repair the open or short in the Red wire between the ECU (C8) and the EGR control solenoid valve.
  30.  
  31. If the engine stalls or runs rough, substitute a known-good ECU and recheck.
  32.  

Legend

See Figure 2



Click image to see an enlarged view

Fig. Fig. 2: EGR system-Legend

  1. If trouble Code 12 flashes or the Check Engine light comes ON, check that all of the connectors between the EGR valve sensor and the PGM-FI ECU are secure.
  2.  
  3. Start the engine and allow it to reach the normal operating temperature or until the cooling fan comes on.
  4.  
  5. Disconnect the No. 11 hose from the EGR valve.
  6.  
  7. Connect a vacuum pump to the disconnected hose and apply vacuum. If there is vacuum present, proceed to Step a. If there is no vacuum present, skip ahead to Step 5.
    1. Disconnect the 4-pin connector from the control box and again check the No. 11 hose for vacuum presence.
    2.  
    3. If there is vacuum present, check the EGR system vacuum hose routing. If the hose routing checks out to be OK, replace the EGR control solenoid valve.
    4.  
    5. If there is no vacuum present, inspect for a short or opening in the white wire of the 4-pin connector. If the wire checks out OK and continuity exists, replace the ECU with a known-good unit and retest.
    6.  

  8.  
  9. Move the vacuum pump/gauge to the EGR valve and apply 8 in. Hg of vacuum to the EGR valve. If the engine does not stall and the EGR valve does not hold vacuum, replace the EGR valve.
  10.  
  11. If the engine stalls and the EGR holds vacuum, disconnect the 4-pin electrical connector from the control box and measure the voltage between the Black/Yellow (+) terminal on the main wire harness and the body ground.
  12.  
  13. If there is no voltage present, check for a short in the wiring in Black/Yellow wire between the solenoid valve and the No. 22 fuse. If there is voltage present, reconnect the No. 11 vacuum hose to the vacuum pump/gauge and start the engine and allow it to idle.
  14.  
  15. Connect the positive battery terminal to the A terminal of the 4 pin connector and connect the negative battery terminal to the B terminal. Watch the vacuum gauge. There should be approximately 8 in. Hg of vacuum within 1 second. If there is the specified amount of vacuum, skip to Step 9. If there is not the specified amount of vacuum, proceed with Step a.
    1. Turn the ignition switch OFF and inspect the No. 11 and No. 5 hoses for leaks, restrictions or misrouting.
    2.  
    3. If the hoses check to be OK, check the EGR control solenoid valve by connecting a vacuum gauge to the lower hose. Start the engine and allow it to idle and check the amount of vacuum present.
    4.  
    5. If there is not approximately 8 in. Hg of vacuum, replace the CVC valve. If there is approximately 8 in. Hg of vacuum, replace the EGR control solenoid valve.
    6.  

  16.  
  17. Turn the ignition switch OFF and reconnect the 4-pin connector. Connect the test harness between the EGR valve lift sensor and the engine wire harness. Turn the ignition switch ON and measure the voltage between the Red (+) and Green (-) terminals. If there is not approximately 5 volts, check for a short in the Yellow/White or the Green/White wiring between the EGR valve and the ECU.
  18.  
  19. If there is approximately 5 volts present, measure the voltage between the White (+) and Green (-) terminals; there should be approximately 1.2 volts. If the prescribed voltage is not present, replace the EGR valve, check for short in Black/White wire between the ECU and the EGR valve lift sensor and substitute a known-good ECU and recheck.
  20.  
  21. Apply 8 in. Hg of vacuum to the EGR valve and watch the voltmeter. Repeat this several times, making sure to completely release all vacuum in between steps. Measure the voltage between the White (+) and Green (-) terminals. The voltage should be approximately 4 volts. If the voltage is not correct, replace the EGR valve.
  22.  
  23. If the voltage is correct, watch the voltage as vacuum increases and decreases. Voltage should consistently increase and decrease also. If it does not, replace the EGR valve. If it does increase and decrease consistently, reconnect the No. 11 hose to the EGR valve.
  24.  
  25. Turn the ignition switch OFF and connect the test harness between the ECU and the connector. Start the engine and allow it to idle.
  26.  
  27. Measure the voltage between the D12 (+) and the D22 (-) terminals, there should be approximately 1.2 volts present. If voltage is not present, repair the open or short in the Black/White wire between the ECU (D12) and the sensor.
  28.  
  29. If the voltage is present, connect the A11 terminal to the A26 terminal with a jumper wire. If the engine does not stall, repair the open or short in the White wire between the ECU (A11) and the EGR control solenoid valve.
  30.  
  31. If the engine stalls substitute a known-good ECU and recheck.
  32.  

Vigor

See Figure 3



Click image to see an enlarged view

Fig. Fig. 3: EGR system-Vigor

  1. If trouble Code 12 flashes or the Check Engine light has come ON, check that all connectors between the EGR valve sensor and the PGM-FI ECU are secure.
  2.  
  3. Warm the engine to normal operating temperature or until the cooling fan comes ON.
  4.  
  5. Disconnect the No. 1 hose from the EGR valve.
  6.  
  7. Connect a vacuum pump to the disconnected hose and apply vacuum. If there is vacuum, proceed to Step a. If there is no vacuum, skip to Step 5.
    1. Disconnect the 4-pin connector from the control box and again check the No. 1 hose for vacuum.
    2.  
    3. If vacuum is present, check EGR system vacuum hose routing. If hose routing checks out OK, replace the EGR control solenoid valve.
    4.  
    5. If vacuum is not present, turn the ignition switch OFF and disconnect the A connector from the ECU. Check for continuity to the ground in the Red wire of the 4-pin connector. If continuity does not exist, replace the ECU with a known-good unit and retest.
    6.  

  8.  
  9. Move the vacuum pump/gauge to the EGR valve and apply 8 in. Hg of vacuum to the EGR valve. If the engine does not stall and the EGR valve does not hold vacuum, replace the EGR valve.
  10.  
  11. If the engine does stall and the EGR holds vacuum, disconnect the 4-pin connector from the control box and measure voltage between the Black/Yellow (+) terminal on the main wire harness and the body ground.
  12.  
  13. If voltage is not present, check for short in wiring in Black/Yellow wire between the solenoid valve and the No. 2 fuse. If voltage is present, reconnect the vacuum hose No. 1 to the vacuum pump/gauge and start the engine and allow it to idle.
  14.  
  15. Connect the positive battery terminal to the B terminal of the of the 4 pin connector and connect the negative battery terminal to the D terminal. Watch the vacuum gauge. There should be approximately 8 in. Hg of vacuum within 1 second. If there is the specified amount, skip to Step 9. If there is not the specified amount, proceed to Step a.
    1. Turn the ignition switch OFF and inspect the No. 1 and No. 2 hoses for leaks, restrictions or misrouting.
    2.  
    3. If the hoses check to be OK, check the EGR control solenoid valve by connecting a vacuum gauge to the lower hose. Start the engine and allow it to idle and check the amount of vacuum present.
    4.  
    5. If there isn't approximately 8 in. Hg of vacuum, replace the CVC valve. If there is approximately 8 in. Hg of vacuum, replace the EGR control solenoid valve.
    6.  

  16.  
  17. Turn the ignition switch OFF and reconnect the 4-pin connector. Disconnect the 3 pin connector from the EGR valve and turn the ignition switch ON . Measure the voltage between the Yellow/White (+) and Green/White (-) terminals. If there is not approximately 5 volts, check for a short in the Yellow/White or the Green/White wiring between the EGR valve and the ECU.
  18.  
  19. If there is approximately 5 volts present, skip to Step 11.If there is no voltage, proceed to Step a.
    1. Measure the voltage between the Yellow/White (+) terminal and the body ground. If there is approximately. 5 volts, repair the open in the Green/White wire between the EGR valve and the ECU.
    2.  
    3. If the prescribed voltage is not present, connect the test harness D connector to the ECU only and not to the main wire harness.
    4.  
    5. Measure the voltage between the D20 (+) and D22 (-) terminals. If there is approximately. 5 volts, repair the short in the Yellow/White wiring between the EGR valve and the ECU. If there is not the prescribed voltage present, substitute a known-good ECU and recheck.
    6.  

  20.  
  21. Turn the ignition switch OFF and reconnect the 3-pin connector to the EGR valve. Connect the test harness between the ECU and the connector.
  22.  
  23. Turn the ignition switch ON and measure the voltage between the D12 (+) and D22 (-) terminals. There should be approximately 1.2 volts with no vacuum and 4.3 volts with 8 in. Hg of vacuum applied. If not, inspect the White/Black wire for a short. If wire checks out OK, replace the EGR valve.
  24.  
  25. The voltage should consistently increase and decrease as the vacuum increases and decreases. If it does not, replace the EGR valve. If voltage does increase and decrease consistently, reconnect the No. 1 hose to the EGR valve.
  26.  
  27. Start the engine and allow it to idle. Connect a jumper wire between terminals A11 and A26.
  28.  
  29. If the engine stalls, substitute a known-good ECU and recheck. If the engine does not stall, repair the short in the Red wire between the ECU (A11) and the EGR control solenoid valve.
  30.  

 
label.common.footer.alt.autozoneLogo