P1078 code

67108877

MEMBER
2005 HONDA CRV
2.4L
4 CYL
4WD
AUTOMATIC
104,000 MILES

Hi, I had a check engine light with error code P1077. Mechanic did some troubleshooting and we ended up replacing the IMRC actuator assembly (Part number 17120-PPA-A01 $285.00) and the bypass control solenoid valve assembly (Part number 36163-PND-A01 $120.00). All was great for a day.

But, after about twenty five miles, I now get the P1078 code!

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1 Reply

ASEMASTER6371

MECHANIC
52,797 POSTS

Good evening.

I attached possible failures and a flow chart for the code. When I got these codes, I replaced the intake manifold complete. The issue is usually the inside of the intake gets carbon-ed up.

Roy

P1077
Item Description
Symptom/DTC P1077
Descriptor
Probable Causes
Engine Control Module (ECM)/Powertrain Control Module (PCM)
Engine Control Module (ECM)/Powertrain Control Module (PCM) Update Needed
Intake Manifold
Intake Manifold Tuning (IMT) Solenoid Valve
Intake Manifold Tuning (IMT) Valve
Poor Connections or Loose Terminals At Intake Manifold Tuning (IMT) Solenoid Valve and Engine Control Module (ECM)/Powertrain Control Module (PCM)
Vacuum Leak Between Intake Manifold Tuning (IMT) Actuator and Intake Manifold Tuning (IMT) Solenoid Valve
Vacuum Leak Between Intake Manifold and Intake Manifold Tuning (IMT) Solenoid Valve
Wire Between Intake Manifold Tuning (IMT) Solenoid Valve and Engine Control Module (ECM)/Powertrain Control Module (PCM) A11 Shorted

flow chart for the code to be checked

DTC P1077: IMT System Malfunction (Low rpm) Stuck Short

Special Tools Required
Vacuum pump/gauge, 0-30 in. Hg, Snap-on YA4000A or equivalent, commercially available

1. Start the engine. Hold the engine speed at 3,000 rpm without load (in Park neutral) until the radiator fan comes on, then let it idle.
2. Do the IMT TEST in the INSPECTION MENU with the HDS.

Is the result OK?

YES - Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the IMT solenoid valve and the ECM/PCM.

NO - Go to step 3.

3. Turn the ignition switch OFF.
4. Check the vacuum hose and the hose connectors between the IMT actuator and IMT solenoid valve.

Are the vacuum hose and the hose connectors OK?

YES - Go to step 5.

NO - Repair the blockage or vacuum leak between the IMT actuator and IMT solenoid valve, then go to step 27.

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5. Disconnect the vacuum hose (A) from the joint (B), and connect a vacuum pump/gauge, 0-30 in. Hg, to the hose.
6. Start the engine.
7. Measure the vacuum.

Is there vacuum?

YES - Go to step 8.

NO - Go to step 13.

8. Turn the ignition switch OFF.
9. Connect the vacuum hose to the IMT actuator.

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10. Disconnect the vacuum hose (A) from the joint (B), and connect a vacuum pump/gauge, 0-30 in. Hg, to the hose.

Does the IMT actuator hold vacuum?

YES - Go to step 11.

NO - Replace the IMT valve, then go to step 27.

11. Do the POS TEST in the INSPECTION MENU with the HDS.
12. Apply vacuum to the hose 28 kPa (8.27 in. Hg, 210 mmHg).

Dose the reading on the HDS change?

YES - Go to step 34.

NO - Replace the IMT valve, then go to step 27.

13. Turn the ignition switch OFF.
14. Connect the vacuum hose to the IMT actuator.

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15. Disconnect the lower vacuum hose (A) from the IMT solenoid valve (B), and connect a vacuum pump/gauge, 0-30 in. Hg, to the hose.
16. Start the engine.
17. Measure the vacuum.

Is there vacuum?

YES - Go to step 20.

NO - Go to step 18.

18. Turn the ignition switch OFF.
19. Check the vacuum hose and the hose connections between intake manifold and IMT solenoid valve.

Are the vacuum hose and the hose connections OK?

YES - Replace the intake manifold, then go to step 27.

NO - Repair the blockage or vacuum leak between the intake manifold and IMT solenoid valve, then go to step 27.

20. Turn the ignition switch OFF.
21. Disconnect the IMT solenoid valve 2P connector.

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22. Check for continuity between IMT solenoid valve 2P connector terminal No.2 and body ground.

Is there continuity?

YES - Go to step 23.

NO - Replace the IMT solenoid valve, then go to step 27.

23. Turn the ignition switch OFF.
24. Jump the SCS line with the HDS.
25. Disconnect ECM/PCM connector A (31 P).

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26. Check for continuity between IMT solenoid valve 2P connector terminal No.2 and body ground.

Is there continuity?

YES - Repair short in the wire between the IMT solenoid valve and the ECM/PCM (A11), then go to step 27.

NO - Go to step 34.

27. Reconnect all connectors.
28. Turn the ignition switch ON (II).
29. Reset the ECM/PCM with the HDS.
30. Do the ECM/PCM idle learn procedure.
31. Do the IMT TEST in the INSPECTION MENU with the HDS.
32. Check for Temporary DTCs or DTCs with the HDS.

Are any Temporary DTCs or DTCs indicated?

YES - If DTC P1077 is indicated, check for poor connections or loose terminals at the IMT solenoid valve and the ECM/PCM, then go to step 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.

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.

NO - If the screen indicates FAILED, check for poor connections or loose terminals at the IMT solenoid valve and the ECM/PCM, then go to step 1. If the screen indicates NOT COMPLETED, go to step 30 and recheck.

34. Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM.
35. Check for Temporary DTCs or DTCs with the HDS.

Are any Temporary DTCs or DTCs indicated?

YES - If DTC P1077 is indicated, check for poor connections or loose terminals at the IMT solenoid valve and the ECM/PCM, then go to step 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.

NO - If the ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM.

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