P1077
Intake Manifold Runner Control System Malfunction (Low RPM)
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The P1077 code is a Honda manufacturer-specific code indicating that the Intake Manifold Runner Control (IMRC) system is not functioning correctly at low engine speeds. The IMRC system uses a set of butterfly valves inside the intake manifold to change the length or volume of the intake path, optimizing airflow and torque at different RPM ranges. At low RPM, the runners are typically kept long to improve low-end torque and fuel efficiency.
When the ECM detects that the IMRC valve is not reaching its expected position at low RPM, it stores this code. Common culprits include vacuum leaks in the lines that operate the valve actuator, a stuck butterfly valve due to carbon buildup, or a failed IMRC solenoid. The issue generally does not create an unsafe driving condition, but you may notice rougher idle and slightly reduced power.
Start by inspecting the vacuum lines running to the IMRC actuator for cracks or disconnections — this is the most common and cheapest fix. If the lines are intact, check the runner valve itself for binding or carbon deposits. Cleaning the intake manifold runners and replacing the solenoid are straightforward repairs for a moderately experienced DIYer.
Severity
Symptoms
- •Rough or unstable idle
- •Slight loss of low-end power
- •Check Engine light illuminated
- •Engine hesitation at low RPM
- •Marginally reduced fuel economy
- •Occasional stalling at idle
Likely Causes
Carbon buildup or mechanical wear can cause the IMRC butterfly valve to stick in one position, preventing it from opening properly at low RPM.
The solenoid that controls vacuum to the runner valve can fail electrically or mechanically, preventing actuation at low engine speeds.
The IMRC system is vacuum-operated on many Honda engines. A cracked, loose, or disconnected vacuum hose prevents proper valve operation.
Corroded connectors, damaged wiring, or poor ground connections between the ECM and the IMRC solenoid can trigger this code.
Estimated Cost
Professional Repair
Includes parts + labor
Common Fixes
- Inspect and replace cracked or disconnected vacuum lines to IMRC actuator
- Clean or replace stuck intake manifold runner valve
- Replace faulty IMRC solenoid valve
- Clean carbon deposits from intake manifold runner butterfly