A 2004 Honda CRV with 278,974 miles arrived with an intermittent Check Engine Light (MIL) and a stored P1077 diagnostic trouble code (DTC), indicating an Intake Manifold Control Runner (IMRC) valve malfunction. The owner had previously ignored the issue, but the illuminated MIL prevented the vehicle from passing state inspection. This article details the diagnostic and repair process for this common problem.
Initial Inspection and Diagnosis of the Honda CRV IMRC
The initial inspection focused on visual checks of the intake manifold, ensuring the vacuum hose was connected and receiving vacuum. The intake runner sensor connection and voltage were also checked. All visual checks appeared normal. A vacuum pump was then used to apply vacuum to the intake manifold diaphragm while monitoring the sensor voltage with a scan tool. Repeated tests revealed inconsistent sensor readings, suggesting a problem with either the IMRC actuator or the sensor itself. A Technical Service Bulletin (TSB 05-052) related to this DTC described a sticking vacuum control solenoid valve, but this vehicle did not exhibit that specific issue.
Isolating the Problem with the 2004 Honda CRV IMRC
To pinpoint the faulty component, the sensor was removed and manually actuated through its full range of motion. The sensor operated correctly, eliminating it as the cause. The next step involved removing the vacuum diaphragm assembly. Upon removal, oil was discovered within the manifold, indicating a potential internal issue. A video of the IMRC actuator’s movement was captured, revealing a delayed response, further confirming a problem with the actuator itself. Video of IMRC Actuator With the intake manifold removed, the intake ports were inspected and found to be carboned up. These were subsequently cleaned.
Replacing the 2004 Honda CRV IMRC
Due to potential warpage of the intake manifold, which could cause binding of a new IMRC actuator, a complete intake manifold assembly (including the runner, diaphragm, and sensor) was recommended. After obtaining owner approval, the new manifold was installed. A test drive allowed the OBD II monitors to reset, ensuring readiness for inspection.
Conclusion
The replacement of the intake manifold assembly resolved the P1077 code and the intermittent MIL issue on this high-mileage 2004 Honda CRV. Ensuring all OBD II monitors are “Ready” is crucial for passing emissions inspections. This repair restored the vehicle to proper running condition and eliminated the Check Engine Light.
