IMRC system – How it works and its impact on your truck.

Understanding the IMRC System in Late Model F150 5.0L Trucks

The Intake Manifold Runner Control (IMRC) system plays a crucial role in optimizing engine performance and efficiency in late-model Ford F150 trucks equipped with the 5.0L V8 engine. Let’s dive into the details of how the IMRC system works and its impact on your truck:

What Is the IMRC System?

1. Purpose: The IMRC system is designed to enhance low-end torque and fuel economy by adjusting the airflow within the intake manifold. It achieves this by varying the length of the intake runners.
2. How It Works:
   • The IMRC system consists of flaps/valves located in the intake manifold.
   • These flaps can open or close, altering the path of incoming air by the use of solenoids actuated by vacuum.
   • At low RPMs, the flaps are closed, creating longer intake runners. This promotes better torque.
   • At higher RPMs, the flaps open, allowing shorter intake runners for improved power.
3. Control Mechanism:
   • The powertrain control module (PCM) monitors various sensors (such as throttle position, engine speed, and load).
   • Based on sensor inputs, the PCM adjusts the position of the IMRC flaps.

Common IMRC Issue:

1. Stuck Flaps:
   • The IMRC flaps can get stuck (most common in the Gen2's 2015-2017). Rarely due to carbon buildup but the majority of the time it is because of mechanical issues like solenoid or sensor failure, also the actuator arms can fail and break as well.
   • The IMRC codes that can come up are:
     P2004 IMRC is stuck open on bank 1
     P2005 IMRC is stuck open on bank 2
     P2006 IMRC is stuck closed on bank 1
     P2007 IMRC is stuck closed on bank 2
   • A stuck flap can affect engine performance, leading to reduced power and efficiency.

Tuning and Solutions:

1. IMRC Delete:
   • Some truck owners choose to disable the IMRC system by locking the flaps open physically by means of lockout kits that secure them from moving. (There are no performance benefits to this with a fully functional IMRC system though).
   • This can be done through custom tuning too if there are not any system failures and everything is functioning properly. (This is common with forced induction power adders).
   • NOTE: After the delete, the truck’s performance may change, but it won’t harm the engine.
2. Custom Tuning:
   • To perform an IMRC delete, you’ll need a tuning device and a custom tune from a reputable tuning company like Oz Tuning.
   • The tuner will reprogram the PCM to keep the flaps open permanently.
   • After tuning, the truck should run normally without any check engine lights (CEL).
   • NOTE: if there is a failure in the IMRC system, tuning cannot control it.
3. Sensor Functionality:
   • If one side’s IMRC sensor is still functional, the truck should run reasonably well.
   • Expect reduced power and a CEL until the custom tune is applied.
4. Physical Lockout:
   • Physically locking out the flaps is an alternative, but it’s not always necessary.
   • A remote tune can achieve the same result without removing the intake manifold.

Conclusion:

Understanding the IMRC system helps you make informed decisions about maintenance, tuning, and modifications for your late-model F150 5.0L truck. Whether you choose to delete the IMRC or keep it operational, consult with a professional tuner to ensure optimal performance.