2011-2021 Subaru WRX STI EJ25 Link G4X Plugin ECU

FREE Link ECU Tuning Cable — $70 Value

Every ECU includes a compatible Link ECU USB tuning cable at no additional cost. You will have what you need to connect your laptop, configure the ECU and begin tuning.

Easy to Install. Powerful. Reliable.

Take full control of your 2011-2021 Subaru WRX STI EJ25 with the Link G4X PlugIn ECU.

This ECU is designed to install directly into the factory ECU enclosure and connect to the original wiring harness with no major rewiring required for supported applications.

You keep the factory-style installation while gaining the power, flexibility, and motorsport features of a modern standalone ECU.

Whether your STI is:

• Stock

• Full Bolt-On

• Built Engine

• Big Turbo

• Flex Fuel

• E85

• Street Driven

• Track Driven

• Drag Raced

the Link G4X gives you the control needed to properly tune and protect your EJ25.

Supported Vehicles

This Link G4X PlugIn ECU supports the following North American / USDM Subaru WRX STI models:

2011-2014 Subaru WRX STI

• GR / GV Chassis

• Hatchback

• Sedan

• EJ25 Engine

• Manual Transmission Only

2015-2021 Subaru WRX STI

• VA Chassis

• EJ-Series Engine

• Manual Transmission Only

Important

FA20-powered WRX models are NOT supported.

This product is specifically for compatible EJ-Series WRX STI applications.

2010 and earlier WRX STI models use a different ECU pinout and require a different Link PlugIn ECU.

Why Upgrade to Link G4X?

The factory Subaru ECU works well for a stock vehicle, but once you start adding serious performance modifications, you quickly reach the point where greater control becomes valuable.

The Link G4X gives your tuner direct control over critical engine functions while adding advanced safety strategies and motorsport features that are difficult or impossible to implement with the factory ECU.

Control areas include:

• Fuel

• Ignition Timing

• Boost

• AVCS / Cam Control

• Flex Fuel

• Knock Control

• Launch Control

• Anti-Lag

• Flat Shift

• Individual Cylinder Corrections

• Engine Protection Strategies

• Auxiliary Inputs and Outputs

• Advanced Datalogging

This makes the G4X an excellent solution for everything from a responsive street STI to a high-horsepower competition build.

Retains Major Factory Features

One of the biggest advantages of this PlugIn ECU is that you don't have to sacrifice many of the factory systems that make the STI enjoyable to drive.

Supported factory functionality includes:

• Factory DCCD System

• SI-Drive

• MFD Display

• Trip Computer

• Gear Display

• ABS

• Stability Control

• Hill Start Assist

• Factory Dash Gauges

• Factory Warning Lamps

• Cruise Control

• Factory Cam Control

• Wheel Speed Data

• Brake Pressure Data

• Steering Wheel Position

• Handbrake Status

• Trac Mode

• Differential Mode

• Rear Demister Status

• Additional CAN Data

SI-Drive can also be repurposed within the ECU to control different tuning strategies or functions depending on your setup.

The Check Engine Light can also be configured for custom warnings such as:

• Knock Warning

• Shift Light

• Engine Protection Alert

• Other ECU-Defined Warnings

Perfect for Modified EJ25 Builds

The Link G4X is an excellent choice for WRX STI combinations using:

• Larger Turbochargers

• Upgraded Injectors

• Upgraded Fuel Pumps

• Flex Fuel

• E85

• External Wastegates

• Electronic Boost Control

• Intake Manifolds

• Front-Mount Intercoolers

• Rotated Turbo Kits

• Built EJ25 Engines

• Upgraded Camshafts

• Additional Sensors

• Fuel Pressure Sensors

• Oil Pressure Sensors

• Exhaust Backpressure Sensors

• Motorsport Electronics

Because the ECU has multiple available inputs and outputs, additional sensors and control strategies can be added as your build evolves.

Advanced Engine Protection

Making power is only part of the equation.

The Link G4X allows your tuner to build advanced safety strategies around the sensors installed on your vehicle.

Depending on your configuration, protection strategies can be created for:

• Low Fuel Pressure

• Low Oil Pressure

• High Coolant Temperature

• High Intake Air Temperature

• Lean Air/Fuel Ratio

• Excessive Boost

• Knock

• Sensor Failure

• Other Critical Engine Conditions

Instead of simply logging a problem after damage occurs, the ECU can be configured to actively respond by reducing boost, limiting RPM, cutting power, or taking other protective action.

For high-performance EJ25 builds, this level of control can be extremely valuable.

Link G4X PlugIn Features

Depending on the application and configuration, G4X features include:

• Up to 6D Fuel Mapping

• Up to 6D Ignition Mapping

• Precision Closed-Loop Cam Control

• Independent Four-Cam Control

• Sequential Fuel Injection

• OEM Trigger Pattern Support

• Factory Idle Control Support

• Advanced Boost Control

• Three Switchable Boost Tables

• Launch Control

• Anti-Lag

• Flat Shift

• Individual Cylinder Fuel Correction

• Individual Cylinder Ignition Correction

• Gear-Based Compensations

• Speed-Based Compensations

• Throttle-Based Boost Control

• Dual Fuel Maps

• Dual Ignition Maps

• Dual Boost Maps

• Staged Injection

• Advanced Knock Control

• Barometric Pressure Compensation

• CAN Communication

• QuickTune Automated Fuel Tuning

• USB Tuning Connection

• Onboard Statistics Recording

• High-Speed Datalogging

512MB Onboard Datalogging

The G4X platform includes substantial onboard logging capability.

This allows your tuner to record important engine data without requiring a laptop to remain connected at all times.

Logging can be extremely useful for:

• Street Tuning

• Drag Racing

• Road Racing

• Diagnosing Problems

• Reviewing Boost Control

• Monitoring Knock

• Checking Fuel Pressure

• Evaluating Engine Protection Events

• Reviewing Track Sessions

Expansion Inputs & Outputs

The Link G4X PlugIn provides additional expansion connections for adding sensors, switches, auxiliary outputs, or other functionality.

Expansion Connector 1

• Pin 1 — Ground

• Pin 2 — +5V

• Pin 3 — Analog Temperature 4

• Pin 4 — Analog Temperature 3

• Pin 5 — Analog Voltage 4

• Pin 6 — Analog Voltage 5

• Pin 7 — Analog Voltage 6

• Pin 8 — Analog Voltage 7

Expansion Connector 2

• Pin 1 — Ground

• Pin 2 — +5V

• Pin 3 — Knock 2

• Pin 4 — Digital Input 11

• Pin 5 — Injector 5

• Pin 6 — Injector 6

• Pin 7 — Injector 7

• Pin 8 — Injector 8

These additional I/O channels allow the ECU to grow with your build instead of forcing you to replace the engine management system later.

CAN Communication

This PlugIn ECU uses the newer 4-pin powered CAN connection.

It does not use the older CANPCB cable.

For connecting compatible CAN devices, use:

Link CANJST4 — Part Number 101-0198

The 4-pin CAN connector provides:

• CAN Communication

• Protected 12V Power

• Ground

The power supply is protected by a self-resetting fuse rated for approximately 3A continuous current.

This makes it easier to connect compatible CAN devices without needing a separate power source.

Important Installation Notes

Before ordering, please verify the following:

• Your vehicle matches one of the supported models listed above

• Your vehicle has an EJ-Series engine

• Your vehicle has a manual transmission

• Your factory ECU connector matches the connector shown in the product photos

• Your wiring harness is in good condition

An intake air temperature sensor is highly recommended, especially for modified, front-mount intercooler, speed-density, or high-performance applications.

Plug-In Installation

The Link G4X processing board installs inside the factory ECU enclosure.

This allows you to retain an OEM-style installation without building an entirely new standalone ECU harness.

For the supported vehicles, installation does not require major modification of the factory wiring loom.

Once installed, the ECU can be connected to a laptop through USB and configured using Link's PCLink software.

FREE Startup Support Included

When you purchase your Link G4X PlugIn ECU from Kugan Tuning, you are not left alone after the ECU arrives.

We include startup and setup support to help you get the system configured correctly.

Support can include assistance with:

• Initial ECU Connection

• PCLink Setup

• Base Calibration Selection

• Injector Configuration

• MAP Sensor Configuration

• Fuel Type Setup

• Trigger Verification

• Sensor Verification

• First Startup

• Idle Setup

• Initial Datalog Review

• Basic Troubleshooting

Our goal is to help get your STI communicating, starting, and operating correctly so you can move forward with tuning.

Professional Tuning Recommended

The Link G4X is a fully programmable standalone engine management system.

A proper calibration is required before the vehicle should be operated under load or boost.

A basemap should only be treated as a starting point.

For best performance, drivability, and engine protection, the ECU should be professionally tuned for your exact:

• Engine

• Turbo

• Injectors

• Fuel System

• Fuel Type

• Boost Level

• Sensors

• Modifications

Remote tuning and dyno tuning services are available separately.

Download the Link ECU Manual

For complete wiring, setup, pinout, and configuration information, refer to the official Link ECU documentation for the WRX11 PlugIn ECU.

Give Your EJ25 the Engine Management It Deserves

If you're building a serious WRX STI, the ECU shouldn't be the limitation.

The Link G4X gives you:

• Full Standalone ECU Control

• Advanced Boost Control

• Flex Fuel Capability

• Motorsport Features

• Advanced Engine Protection

• High-Speed Datalogging

• Expanded Sensor Inputs

• Factory Feature Integration

• Room to Grow With Your Build

Upgrade Your 2011-2021 WRX STI EJ25 to Link G4X Today.

Get the control, logging, protection, and tuning capability needed to take your STI to the next level.