How To Install a HKS FCD in a Mitsubishi Evolution

How To Install a HKS FCD in a Mitsubishi Evolution


Meant to combat fuel cut in factory turbocharged vehicles, the HKS FCD is one of the best known fuel cut piggyback devices on the market. While support has sagged since the early to mid 90s for this piggyback device, this part still enjoys a large following for people looking to circumvent fuel cut.

When you are modifying your stock turbocharged vehicle, one of the biggest byproducts of increasing flow is the accompanying increase in boost. If the fuel and spark is raised appropriately, the engine produces more horsepower and torque. Unfortunately many customers modify their vehicles and raise boost without the required fuel modifications.


This causes your injector duty cycle to climb, as your factory turbocharged ECU attempts to deliver more fuel to match the increase in boost. If fuel injector duty cycle continues to climb, the factory ECU will cut the party short by cutting fuel delivery to the engine in order to prevent engine damage. This is known as fuel cut and that’s exactly what the HKS Fuel Cut Defencer was designed to combat.


Today I’ll be showing you how to install a HKS FCD in a 2004 Mitsubishi Evolution VIII, to reduce the ECU’s ability to cut the fuel delivery to the engine. Be aware however you are inherently installing a device that prohibits your vehicle’s standard failsafe mechanism. Installation of this unit can run the risk of overboosting your vehicle and causing serious detonation if you aren’t aware of what you are doing.

In other words, proceed at your own risk. This How To Install a HKS FCD in a Mitsubishi Evolution Guide is meant for enthusiasts who are comfortable tuning their own vehicle.

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The unit we are installing today is HKS part number 4501-RM003 and it’s a Type K3 device that we’ll be splicing into the ECU. Like most other piggyback devices, the HKS FCD installs easily and can be done using vampire clips, although soldering is recommended. The HKS FCD is also recommended to operate inline with a HKS VPC or the F-CON unit, check here for more information.

The ECU on this Evolution is located behind the glovebox and requires you to slide out the plastic clips inside. Open your glove box and gently push on the stopper pin located on side towards the driver. Once this pin is pushed out you can slide the glove box to the left gently so that it can be pulled down and removed.


Once your glovebox has been swung down and removed from the dashboard, you can undo the 10mm bolts that hold the ECU in place. There are a total of three bolts that hold the bracket and ECU, undo these and slide your ECU out towards you.

Face the ECU towards you, with the wiring harnesses pointed in your direction. Notice the orientation of the ECU and plugs, and now we can get started.

To kick off our How To Install a HKS FCD in a Mitsubishi Evolution Guide, you will be teeing in the power wires for the HKS FCD unit. Take the red wire from the HKS FCD and tee this wire into your switched power on PIN 25 for voltage supplied with the key set to the “ON” position.

Next we’ll be wiring in the low reference or ground signal wire for the HKS FCD, take the black wire and tee this wire into PIN 26 on the Evo ECU.


Because our Mitsubishi Evolution uses a airflow reading instead of manifold pressure, RPM is required. Typically for all Type K3 FCD units, this RPM wire is needed so that the FCD can determine engine speed. The RPM wire we’ll need to hook up is the GREEN HKS FCD wire which is the RPM signal. This goes to the 4G63 Tach output wire, which is PIN 58.

The last wire is the MAF signal wire, which is PIN 90 on the Mitsubishi ECU. You will need to cut this wire and connect to different wires on the HKS FCD wiring connector. Cut this wire but leave enough slack on either end so that you can work comfortably. Connect the YELLOW HKS FCD wire to the ECU side of the harness, and the WHITE HKS FCD wire heads to the engine harness and your mass air flow (MAF) connector.

Congratulations, you have now completed our How To Install a HKS FCD in a Mitsubishi Evolution Guide.