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DTC P1077: Intake Manifold Runner Control System Malfunction (Low Rpm)

WARNING: This page is about a different car, the 2003 Acura RSX. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform ECM/PCM reset procedure. See ECM/PCM RESET PROCEDURE/CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM.
  2. Start engine and hold at 3000 RPM, with no load (in park or neutral), until cooling fan comes on. Using scan tool, check engine speed at idle with no load. If DTC P1077 is set, go to next step. If DTC is not set, problem is intermittent. System is okay at this time. Check for poor connection(s) or loose wire(s) at Intake Manifold Runner Control (IMRC) solenoid valve 2-pin harness connector and ECM/PCM 24-pin "B" harness connector. See Figure .
  3. Disconnect vacuum hose from IMRC valve and connect to vacuum gauge. See Fig 1 . If vacuum is not present, go to next step. If vacuum is present, go to step  8 .
    Fig 1: Testing IMRC Solenoid Valve
    G00110167Courtesy of AMERICAN HONDA MOTOR CO., INC.
  4. Check vacuum hose between IMRC valve and IMRC solenoid valve. If vacuum hose is okay, go to next step. If vacuum hose is faulty, repair or replace as necessary.
  5. Disconnect lower vacuum hose from IMRC solenoid valve and connect to vacuum gauge. See Fig 2 . If vacuum is present, go to next step. If vacuum is not present, repair blockage or leak between intake manifold and IMRC solenoid valve.
    Fig 2: Checking IMRC Solenoid Valve Vacuum Source
    G00110168Courtesy of AMERICAN HONDA MOTOR CO., INC.
  6. Reconnect lower vacuum hose to IMRC solenoid valve. Disconnect IMRC valve vacuum hose and connect to vacuum gauge. See Fig 1 . Disconnect IMRC solenoid valve 2-pin harness connector. If vacuum is present, go to next step. If vacuum is not present, replace IMRC solenoid valve.
  7. Turn ignition switch off. Disconnect ECM/PCM 24-pin "B" harness connector. See Figure . Check for continuity between ground and IMRC solenoid valve 2-pin harness connector terminal No. 2 (Red/Blue wire). If continuity is present, repair short in Red/Blue wire between ECM/PCM 24-pin "B" harness connector terminal No. 22 and IMRC solenoid valve. If continuity is not present, update ECM/PCM or substitute with known-good ECM/PCM. If symptom or indication goes away, replace original ECM/PCM.
  8. Turn ignition switch off. Connect vacuum pump to IMRC valve and apply vacuum. See Fig 3 . If IMRC valve holds vacuum, go to next step. If IMRC valve does not hold vacuum, replace IMRC valve assembly.
    Fig 3: Testing IMRC Valve
    G00110169Courtesy of AMERICAN HONDA MOTOR CO., INC.
  9. Disconnect IMRC valve position sensor 3-pin harness connector. Measure resistance between IMRC valve position sensor 3-pin connector terminals No. 2 and 3 while applying vacuum to IMRC valve. If about 9500 ohms is present, update ECM/PCM or substitute with known-good ECM/PCM. If symptom or indication goes away, replace original ECM/PCM. If resistance is not as specified, replace IMRC valve assembly.
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