Home ReviewsRefund
Home/Acura/MDX/Acura MDX II (2006-2010)/Repair manual/Mechanical/Intake Air System
Contents Wiring diagrams Section: Mechanical All sections

Intake Air System Acura MDX II

Mechanical 23 illustrations ~3004 words

Scheme 1

Scheme 1: Component Location Index
Scheme 1: Component Location Index

DTC P1077: IMT Valve Stuck in High RPM Position

Note. Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information (see GENERAL TROUBLESHOOTING INFORMATION ).

Scheme 2

Scheme 2: DTC P1077: IMT Valve Stuck in High RPM Position
Scheme 2: DTC P1077: IMT Valve Stuck in High RPM Position

Scheme 3

Scheme 3
Scheme 3

Scheme 4

Scheme 4
Scheme 4

Scheme 5

Scheme 5
Scheme 5

Scheme 6

Scheme 6
Scheme 6

Scheme 7

Scheme 7
Scheme 7

Scheme 8

Scheme 8
Scheme 8

Scheme 9

Scheme 9
Scheme 9
  1. Turn the ignition switch ON (II).
  2. Clear the DTC with the HDS.
  3. Start the engine, and then let it idle without load (in Park or neutral) until the radiator fan comes on.
  4. Start the engine, and hold the engine speed above 3,800 rpm.
  5. Check the IMT VALVE CMD in the DATA LIST with the HDS. Is OPEN indicated? YES - Go to step 6. NO - Go to step 35 .
  6. Check the IMT VALVE SW in the DATA LIST with the HDS. Is CLOSE indicated? YES - Go to step 7. NO - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the IMT actuator and the PCM.
  7. Let the engine idle, then turn the ignition switch OFF.
  8. Disconnect the IMT actuator 5P connector.
  9. Turn the ignition switch ON (II).
  10. Measure voltage between IMT actuator 5P connector terminal No. 1 and body ground. Is there about 5 V? YES - Go to step 11. NO - Repair open in the wire between the PCM (C11) and the IMT actuator, then go to step 26 .
  11. Measure voltage between IMT actuator 5P connector terminal No. 3 and body ground. Is there about 5 V? YES - Go to step 12. NO - Go to step 16 .
  12. Turn the ignition switch OFF.
  13. Jump the SCS line with the HDS.
  14. Disconnect PCM connector C (49P).
  15. Check for continuity between PCM connector terminal C16 and IMT actuator 5P connector terminal No. 2. Is there continuity? YES - Go to step 20 . NO - Repair open in the wire between the PCM (C16) and the IMT actuator, then go to step 26 .
  16. Turn the ignition switch OFF.
  17. Jump the SCS line with the HDS.
  18. Disconnect PCM connector B (49P).
  19. Check for continuity between PCM connector terminal B19 and IMT actuator 5P connector terminal No. 3. Is there continuity? YES - Go to step 34 . NO - Repair open in the wire between the PCM (B19) and the IMT actuator, then go to step 26 .
  20. Check for continuity between PCM connector terminal C48 and body ground. Is there continuity? YES - Repair short in the wire between the PCM (C48) and the IMT actuator, then go to step 26 . NO - Go to step 21.
  21. Check for continuity between PCM connector terminal C48 and IMT actuator 5P connector terminal No. 5. Is there continuity? YES - Go to step 22. NO - Repair open in the wire between the PCM (C48) and the IMT actuator, then go to step 26 .
  22. Check for continuity between PCM connector terminal C49 and body ground. Is there continuity? YES - Repair short in the wire between the PCM (C49) and the IMT actuator, then go to step 26 . NO - Go to step 23.
  23. Check for continuity between PCM connector terminal C49 and IMT actuator 5P connector terminal No. 4. Is there continuity? YES - Go to step 24. NO - Repair open in the wire between the PCM (C49) and the IMT actuator, then go to step 26 .
  24. Remove the IMT actuator (see «IMT ACTUATOR REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/mechanical/#intake-air-system) ).
  25. Move the IMT valve by hand. Does it move smoothly? YES - Substitute a known-good IMT actuator (see «IMT ACTUATOR REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/mechanical/#intake-air-system) ), then go to step 26 and recheck. If DTC P1078 is not indicated, replace the IMT actuator (see «IMT ACTUATOR REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/mechanical/#intake-air-system) ), then go to step 26. If DTC P1078 is indicated, go to step 35 . NO - Remove the engine cover (see step 1 on «INTAKE MANIFOLD REMOVAL AND INSTALLATION»(/acura/mdx/ii-2006-2010/remont/exhaust/#intake-manifold-and-exhaust-system) ), and repair the stuck valve. If necessary, replace the intake manifold (see «INTAKE MANIFOLD REMOVAL AND INSTALLATION»(/acura/mdx/ii-2006-2010/remont/exhaust/#intake-manifold-and-exhaust-system) ), then go to step 26.
  26. Reconnect all connectors.
  27. Turn the ignition switch ON (II).
  28. Reset the PCM with the HDS.
  29. Do the PCM idle learn procedure (see «PCM IDLE LEARN PROCEDURE»(/acura/mdx/ii-2006-2010/remont/engine-control-systems/#idle-control-system__pcm-idle-learn-procedure) ).
  30. Start the engine, and then let it idle without load (in Park or neutral) until the radiator fan comes on.
  31. Start the engine, and hold the engine speed at 3,800 rpm for 10 seconds, then let it idle.
  32. Check for Temporary DTCs or DTCs with the HDS. Is DTC P1077 indicated? YES - Check for poor connections or loose terminals at the IMT actuator and the PCM, then go to step 1 . NO - Go to step 33.
  33. Monitor the OBD STATUS for DTC P1077 in the DTCs MENU with the HDS. Does the screen indicate PASSED? YES - Troubleshooting is complete. If any other Temporary DTCs or DTCs were indicated in step 32 , go to . NO - If the screen indicates FAILED, check for poor connections or loose terminals at the IMT actuator and the PCM, then go to step 1 . If the screen indicates NOT COMPLETED, go to step 31 .
  34. Reconnect all connectors.
  35. Update the PCM if it does not have the latest software (see «PCM UPDATE»(/acura/mdx/ii-2006-2010/remont/testing-diagnostics/#pgm-fi-system__pcm-update) ), or substitute a known-good PCM (see «SUBSTITUTING THE PCM»(/acura/mdx/ii-2006-2010/remont/testing-diagnostics/#fuel-and-emissions-systems__substituting-the-pcm) ).
  36. Start the engine, and then let it idle without load (in Park or neutral) until the radiator fan comes on.
  37. Start the engine, and hold the engine speed at 3,800 rpm for 10 seconds, then let it idle.
  38. Check for Temporary DTCs or DTCs with the HDS. Is DTC P1077 indicated? YES - Check for poor connections or loose terminals at the IMT actuator and the PCM. If the PCM was updated, substitute a known-good PCM (see «SUBSTITUTING THE PCM»(/acura/mdx/ii-2006-2010/remont/testing-diagnostics/#fuel-and-emissions-systems__substituting-the-pcm) ), then go to step 37 . If the PCM was substituted, go to step 1 . NO - Go to step 39.
  39. Monitor the OBD STATUS for DTC P1077 in the DTCs MENU with the HDS. Does the screen indicate PASSED? YES - If the PCM was updated, troubleshooting is complete. If the PCM was substituted, replace the original PCM (see «PCM REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/testing-diagnostics/#pgm-fi-system__pcm-replacement) ). If any other Temporary DTCs or DTCs were indicated in step 38 , go to the indicated DTCs troubleshooting. NO - If the screen indicates FAILED, check for poor connections or loose terminals at the IMT actuator and the PCM. If the PCM was updated, substitute a known-good PCM (see «SUBSTITUTING THE PCM»(/acura/mdx/ii-2006-2010/remont/testing-diagnostics/#fuel-and-emissions-systems__substituting-the-pcm) ), then go to step 37 . If the PCM was substituted, go to step 1 . If the screen indicates NOT COMPLETED, go to step 37 .

DTC P1078: IMT Valve Stuck in Low RPM Position

Note. Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information (see GENERAL TROUBLESHOOTING INFORMATION ).

Scheme 10

Scheme 10: DTC P1078: IMT Valve Stuck in Low RPM Position
Scheme 10: DTC P1078: IMT Valve Stuck in Low RPM Position

Scheme 11

Scheme 11
Scheme 11

Scheme 12

Scheme 12
Scheme 12

Scheme 13

Scheme 13
Scheme 13

Scheme 14

Scheme 14
Scheme 14
  1. Turn the ignition switch ON (II).
  2. Clear the DTC with the HDS.
  3. Start the engine, and let it idle.
  4. Check the IMT VALVE CMD in the DATA LIST with the HDS. Is CLOSE indicated? YES - Go to step 5. NO - Go to step 29 .
  5. Check the IMT VALVE SW in the DATA LIST with the HDS. Is OPEN indicated? YES - Go to step 6. NO - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the IMT actuator and the PCM.
  6. Turn the ignition switch OFF.
  7. Disconnect the IMT actuator 5P connector.
  8. Turn the ignition switch ON (II).
  9. Check the IMT VALVE SW in the DATA LIST with the HDS. Is CLOSE indicated? YES - Go to step 14 . NO - Go to step 10.
  10. Turn the ignition switch OFF.
  11. Jump the SCS line with the HDS.
  12. Disconnect PCM connector B (49P).
  13. Check for continuity between PCM connector terminal B19 and body ground. Is there continuity? YES - Repair short in the wire between the PCM (B19) and the IMT actuator, then go to step 23 . NO - Go to step 30 .
  14. Turn the ignition switch OFF.
  15. Jump the SCS line with the HDS.
  16. Disconnect PCM connector C (49P).
  17. Check for continuity between PCM connector terminal C48 and body ground. Is there continuity? YES - Repair short in the wire between the PCM (C48) and the IMT actuator, then go to step 23 . NO - Go to step 18.
  18. Check for continuity between PCM connector terminal C48 and IMT actuator 5P connector terminal No. 5. Is there continuity? YES - Go to step 19. NO - Repair open in the wire between the PCM (C48) and the IMT actuator, then go to step 23 .
  19. Check for continuity between PCM connector terminal C49 and body ground. Is there continuity? YES - Repair short in the wire between the PCM (C49) and the IMT actuator, then go to step 23 . NO - Go to step 20.
  20. Check for continuity between PCM connector terminal C49 and IMT actuator 5P connector terminal No. 4. Is there continuity? YES - Go to step 21. NO - Repair open in the wire between the PCM (C49) and the IMT actuator, then go to step 23 .
  21. Remove the IMT actuator (see «IMT ACTUATOR REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/mechanical/#intake-air-system) ).
  22. Move the IMT valve by hand. Does it move smoothly? YES - Substitute a known-good IMT actuator (see «IMT ACTUATOR REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/mechanical/#intake-air-system) ), then go to step 23 and recheck. If DTC P1077 is not indicated, replace the IMT actuator (see «IMT ACTUATOR REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/mechanical/#intake-air-system) ), then go to step 23. If DTC P1077 is indicated, go to step 31 . NO - Remove the engine cover (see step 1 on «INTAKE MANIFOLD REMOVAL AND INSTALLATION»(/acura/mdx/ii-2006-2010/remont/exhaust/#intake-manifold-and-exhaust-system) ), and repair the stuck valve. If necessary, replace the intake manifold (see «INTAKE MANIFOLD REMOVAL AND INSTALLATION»(/acura/mdx/ii-2006-2010/remont/exhaust/#intake-manifold-and-exhaust-system) ), then go to step 23.
  23. Reconnect all connectors.
  24. Turn the ignition switch ON (II).
  25. Reset the PCM with the HDS.
  26. Do the PCM idle learn procedure (see «PCM IDLE LEARN PROCEDURE»(/acura/mdx/ii-2006-2010/remont/engine-control-systems/#idle-control-system__pcm-idle-learn-procedure) ).
  27. Check for Temporary DTCs or DTCs with the HDS. Is DTC P1077 indicated? YES - Check for poor connections or loose terminals at the IMT actuator and the PCM. If the PCM was updated, substitute a known-good PCM (see «SUBSTITUTING THE PCM»(/acura/mdx/ii-2006-2010/remont/testing-diagnostics/#fuel-and-emissions-systems__substituting-the-pcm) ), then recheck. If the PCM was substituted, go to step 1 . NO - Go to step 28.
  28. Monitor the OBD STATUS for DTC P1078 in the DTCs MENU with the HDS. Does the screen indicate PASSED? YES - If the PCM was updated, troubleshooting is complete. If the PCM was substituted, replace the original PCM (see «PCM REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/testing-diagnostics/#pgm-fi-system__pcm-replacement) ). If any other Temporary DTCs or DTCs were indicated in step 27 , go to the indicated DTCs troubleshooting. NO - If the screen indicates FAILED, check for poor connections or loose terminals at the IMT actuator and the PCM. If the PCM was updated, substitute a known-good PCM (see «SUBSTITUTING THE PCM»(/acura/mdx/ii-2006-2010/remont/testing-diagnostics/#fuel-and-emissions-systems__substituting-the-pcm) ), then recheck. If the PCM was substituted, go to step 1 . If the screen indicates NOT COMPLETED, keep idling until a result comes on.
  29. Turn the ignition switch OFF.
  30. Reconnect all connectors.
  31. Update the PCM if it does not have the latest software (see «PCM UPDATE»(/acura/mdx/ii-2006-2010/remont/testing-diagnostics/#pgm-fi-system__pcm-update) ), or substitute a known-good PCM (see «SUBSTITUTING THE PCM»(/acura/mdx/ii-2006-2010/remont/testing-diagnostics/#fuel-and-emissions-systems__substituting-the-pcm) ).
  32. Check for Temporary DTCs or DTCs with the HDS. Is DTC P1078 indicated? YES - Check for poor connections or loose terminals at the IMT actuator and the PCM. If the PCM was updated, substitute a known-good PCM (see «SUBSTITUTING THE PCM»(/acura/mdx/ii-2006-2010/remont/testing-diagnostics/#fuel-and-emissions-systems__substituting-the-pcm) ), then recheck. If the PCM was substituted, go to step 1 . NO - Go to step 33.
  33. Monitor the OBD STATUS for DTC P1078 in the DTCs MENU with the HDS. Does the screen indicate PASSED? YES - If the PCM was updated, troubleshooting is complete. If the PCM was substituted, replace the original PCM (see «PCM REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/testing-diagnostics/#pgm-fi-system__pcm-replacement) ). If any other Temporary DTCs or DTCs were indicated in step 32 , go to the indicated DTCs troubleshooting. NO - If the screen indicates FAILED, check for poor connections or loose terminals at the IMT actuator and the PCM. If the PCM was updated, substitute a known-good PCM (see «SUBSTITUTING THE PCM»(/acura/mdx/ii-2006-2010/remont/testing-diagnostics/#fuel-and-emissions-systems__substituting-the-pcm) ), then recheck. If the PCM was substituted, go to step 1 . If the screen indicates NOT COMPLETED, keep idling until a result comes on.

Carbon Accumulation Check

Note. If the malfunction indicator lamp (MIL) has been reported on, check for diagnostic trouble codes (DTCs).

Scheme 15

Scheme 15: Carbon Accumulation Check
Scheme 15: Carbon Accumulation Check
  1. Connect the HDS to the data link connector (DLC) (A) located under the driver's side of the dashboard.
  2. Turn the ignition switch ON (II).
  3. Make sure the HDS communicates with the PCM. If it doesn't, go to the DLC circuit troubleshooting (see «DLC CIRCUIT TROUBLESHOOTING»(/acura/mdx/ii-2006-2010/remont/testing-diagnostics/#pgm-fi-system__dlc-circuit-troubleshooting) ).
  4. Start the engine. Hold the engine speed at 3,000 rpm without load (in Park or neutral) until the radiator fan comes on, then let it idle.
  5. Check the REL TP SENSOR in the DATA LIST with the HDS. The reading should be below 4.3 deg. If it is not, clean the throttle body (see «THROTTLE BODY CLEANING»(/acura/mdx/ii-2006-2010/remont/mechanical/#intake-air-system__throttle-body-cleaning) ).

Throttle Position Learning Check

Note. If the malfunction indicator lamp (MIL) has been reported on, check for diagnostic trouble codes (DTCs).

Scheme 16

Scheme 16: Throttle Position Learning Check
Scheme 16: Throttle Position Learning Check
  1. Connect the HDS to the data link connector (DLC) (A) located under the driver's side of the dashboard.
  2. Turn the ignition switch ON (II).
  3. Make sure the HDS communicates with the PCM. If it doesn't, go to the DLC circuit troubleshooting (see «DLC CIRCUIT TROUBLESHOOTING»(/acura/mdx/ii-2006-2010/remont/testing-diagnostics/#pgm-fi-system__dlc-circuit-troubleshooting) ).
  4. Select the INSPECTION MENU with the HDS.
  5. Do the TP POSITION CHECK in the ETCS TEST. If needed, clean the throttle body (see «THROTTLE BODY CLEANING»(/acura/mdx/ii-2006-2010/remont/mechanical/#intake-air-system__throttle-body-cleaning) ).

Throttle Body Cleaning

CAUTIONDo not insert your fingers into the installed throttle body when you turn the ignition switch ON (II) or while the ignition switch is ON (II). If you do, you will seriously injure your fingers if the throttle valve is activated.

Scheme 17

Scheme 17
Scheme 17

Scheme 18

Scheme 18
Scheme 18
  1. Make sure the ignition switch is turned OFF.
  2. Check for damage to the air cleaner. If the air cleaner is damaged, replace it (see «AIR CLEANER ELEMENT INSPECTION/ REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/mechanical/#intake-air-system) ).
  3. Remove the throttle body (see «THROTTLE BODY REMOVAL/INSTALLATION»(/acura/mdx/ii-2006-2010/remont/mechanical/#intake-air-system__throttle-body-removalinstallation) ).
  4. Clean off the carbon from the throttle valve and inside the throttle body with a paper towel soaked in throttle plate and induction cleaner. NOTE: Remove the throttle body to clean it. Be careful not to pinch your fingers. To avoid removing the molybdenum coating, do not clean the bearing area of the throttle shaft (A). Do not spray throttle plate and induction cleaner directly on the throttle body. Use Acura genuine throttle plate and induction cleaner.
  5. Install the throttle body (see «THROTTLE BODY REMOVAL/INSTALLATION»(/acura/mdx/ii-2006-2010/remont/mechanical/#intake-air-system__throttle-body-removalinstallation) ).
  6. Connect the HDS to the data link connector (DLC) (A) located under the driver's side of the dashboard.
  7. Turn the ignition switch ON (II).
  8. Make sure the HDS communicates with the PCM. If it doesn't, go to the DLC circuit troubleshooting (see «DLC CIRCUIT TROUBLESHOOTING»(/acura/mdx/ii-2006-2010/remont/testing-diagnostics/#pgm-fi-system__dlc-circuit-troubleshooting) ).
  9. Reset the PCM with the HDS.
  10. Select the ETCS TEST in the INSPECTION MENU with the HDS.
  11. Select the TP POSITION CHECK and clear the throttle position (TP) learned value.
  12. Turn the ignition switch OFF.
  13. Turn the ignition switch ON (II), and wait 2 seconds without pressing the accelerator pedal.

Scheme 19

Scheme 19: Air Cleaner Removal/Installation
Scheme 19: Air Cleaner Removal/Installation
  1. Disconnect the MAF sensor/IAT sensor connector (A).
  2. Remove the bolts (B).
  3. Remove the air cleaner (C).
  4. Install the parts in the reverse order of removal.

Scheme 20

Scheme 20: Air Cleaner Element Inspection/ Replacement
Scheme 20: Air Cleaner Element Inspection/ Replacement
  1. Open the air cleaner housing cover (A).
  2. Remove the air cleaner element (B) from the air cleaner housing (C).
  3. Check the air cleaner element for damage or clogging. If there is damage or clogging, replace the air cleaner element. NOTE: Do not use compressed air to clean the air cleaner element.
  4. Clean and remove any debris from inside the air cleaner housing.
  5. Install the parts in the reverse order of removal.
  1. If you did not replace the air cleaner element, this procedure is complete.
  2. If the maintenance minder required to the air cleaner element, reset the maintenance minde(See «RESETTING THE MAINTENANCE INFORMATION DISPLAY»(/acura/mdx/ii-2006-2010/remont/reset-procedures/#maintenance) .
  3. If you replace the air cleaner element, reset the PCM with the HDS, and do the PCM idle learn procedure(See «PCM IDLE LEARN PROCEDURE»(/acura/mdx/ii-2006-2010/remont/engine-control-systems/#idle-control-system__pcm-idle-learn-procedure) ).

Scheme 21

Scheme 21: Resonator Removal/Installation
Scheme 21: Resonator Removal/Installation
  1. Remove the air cleaner.
  2. Do the battery terminal disconnection procedure.(See «DISCONNECTION»(/acura/mdx/ii-2006-2010/remont/body-electrical/#battery__disconnection) ).
  3. Remove the battery.
  4. Remove the front bumper (see «FRONT BUMPER REMOVAL/INSTALLATION»(/acura/mdx/ii-2006-2010/remont/exterior-body-panels/#bumpers__front-bumper-removalinstallation) ).
  5. Remove the left side headlight (see «HEADLIGHT REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/exterior-lights/#exterior-lights) ).
  6. Remove the clips (A) and cover (B).
  7. Remove the bolts (C), and resonator (D).
  8. Install the parts in the reverse order of removal.
  9. Do the battery terminal reconnection procedure(See «RECONNECTION»(/acura/mdx/ii-2006-2010/remont/body-electrical/#battery__reconnection)
  10. Adjust the headlight to local requirements (see «HEADLIGHT ADJUSTMENT»(/acura/mdx/ii-2006-2010/remont/exterior-lights/#exterior-lights__headlight-adjustment) ).

Scheme 22

Scheme 22: IMT Actuator Replacement
Scheme 22: IMT Actuator Replacement
  1. Remove the engine cover (see step 1 «INTAKE MANIFOLD REMOVAL AND INSTALLATION»(/acura/mdx/ii-2006-2010/remont/exhaust/#intake-manifold-and-exhaust-system) ).
  2. Disconnect the IMT actuator connector (A).
  3. Remove the bolts (B) and the IMT actuator (C).
  4. Install the parts in the reverse order of removal with a new O-ring (D).

Throttle Body Removal/Installation

CAUTIONDo not insert your fingers into the installed throttle body when you turn the ignition switch ON (II) or while the ignition switch is ON (II). If you do, you will seriously injure your fingers if the throttle valve is activated.

Note. If you are replacing the throttle body, begin at step 1 . If you are removing the throttle body temporarily, begin at step 5 .

Scheme 23

Scheme 23
Scheme 23
  1. Connect the HDS while the engine is stopped.
  2. Select the INSPECTION MENU with the HDS.
  3. Do the TP POSITION CHECK in the ETCS TEST.
  4. Turn the ignition switch OFF.
  5. Disconnect the MAP sensor connector (A).
  6. Remove the intake air duct (B).
  7. Disconnect the throttle body connector (C).
  8. Disconnect and plug the water bypass hoses (D).
  9. Remove the throttle body (E).
  10. Install the parts in the reverse order of removal with a new gasket (F). NOTE: Do the PCM idle learn procedure after the throttle body has been replaced (see «PCM IDLE LEARN PROCEDURE»(/acura/mdx/ii-2006-2010/remont/engine-control-systems/#idle-control-system__pcm-idle-learn-procedure) ). Refill the radiator with engine coolant (see «COOLANT CHECK»(/acura/mdx/ii-2006-2010/remont/cooling-system-mechanical/#cooling-system) ).

More articles — Engine