Link G4X plug-in Toyota MR2 (V1) / Celica ST185

**Currently 1 Unit in Stock**

Please Note: ECUs available on back-order usually ship within 2-3 working days

$ 2,150.00$ 2,370.00

Incl. Tax (NZ Customers)

Excl. Tax (International Customers)


Link G4X plug-in Toyota MR2 (V1) / Celica ST185


Link Part #TST185X (SKU: 221-4000)


The Link G4X range of engine management systems builds upon the previous G4+ ECUs by featuring an all new micro-processor, an upgraded communications chip and expanded data logging. These improvements allow for a more responsive and accurate tune, much faster download speeds and far greater internal data logging capacity.


The Link G4X range of engine management systems are well known for delivering class-leading performance without sacrificing factory levels of drivability. The G4X plug-in ECUs are designed to be the most complete plug-in solution yet.


This Toyota MR2 plug-in ECU will save you time and money as they will plug straight into your vehicle’s original wiring loom without the need for messy adapter harnesses. It replaces the original circuit board inside the factory ECU enclosure and mounts using the factory brackets.  It is suitable for 3SGE powered SW20 (MR2 version 1) and the ST185 (in either naturally aspirated (NA) or turbocharged configurations) using a manual transmission as detailed below. Automatics are not supported.


  • Toyota MR2 – SW20 1989-1992 models with 3SGE engine
  • Toyota MR2 – SW20 1989-1992 models with 3SGTE engine
  • Toyota Celica – ST185 1989-1993 models with 3SGE engine
  • Toyota Celica – ST185 1989-1993 models with 3SGTE engine


This Link G4X plug-in ECU integrates fully with the factory car  and will keep the factory dash working (water temperature gauge, fuel level light, air conditioning, etc) as it did with the factory ECU.


Once the installation is complete, the Link G4X allows a good tuner to achieve an optimal state of tune to get the most out of any combination of modifications.


All Link G4X plug-in ECUs come with a base map. While these maps are designed to help save time for you and your tuner, it is essential that these are used simply as a starting point for further tuning.


For naturally aspirated (N/A) versions the Link G4X plug-in enables the removal of the air flow meter (AFM), the engine can easily be converted to speed density by removing the air flow meter and instead using the factory MAP sensor and the intake air temperature sensor (Note: not all of the 3SGE engines have airflow meters)


Likewise, for turbocharged applications, the factory air flow meter is no longer required and can now use the factory MAP sensor (Up to 18psi, any more boost will require a replacement sensor, the one listed below is a direct plug in replacement but will require re-calibration).


Toyota plug-in 4 Bar MAP sensor


This ECU can also be setup to control boost with an external boost solenoid. This eliminates the need to purchase a separate electronic boost control system.


The vehicle’s original sensors & actuators are used except for the following exceptions:

  • MAP sensor -The factory MAP sensor is supported. This capable of measuring up to 1.24Bar (18psi) boost. If higher boost pressures are required then an aftermarket external MAP sensor may be used and connected to the factory MAP sensor wiring. The airflow meter is not required.
  • Inlet Air Temp Sensor (IAT) –  If the engine is a model with an airflow meter installed from factory it will have an IAT sensor fitted inside the air flow meter . While this factory IAT sensor is supported by the G4X plug-in ECU on naturally aspirated engines, the factory air flow meter would need to be kept in place to use the IAT sensor. For the engines that do not have an AFM, there will be a factory IAT that can also be used on naturally aspirated cars. For best results we recommend an alternative IAT sensor to be fitted to the intercooler pipe just prior to the plenum entrance (these are available from NZEFI). This may use the existing IAT wiring or connect to the expansion connector of the ECU.
  • Boost control – The factory boost solenoid wiring on the MR2 and Celica turbo variants may be used, however an appropriate boost solenoid must be used (these are available from NZEFI).
  • Injectors – The G4X plug in is designed to be used with high impedance injectors. Low impedance injectors may only be used with ballast resistors. Luckily, the MR2 and Celica models have low impedance injectors with a factory-fitted ballast system so no changes are necessary. DO NOT remove the factory fitted ballast resistors unless the injectors are changed to a high impedance type.


Extra sensor inputs

The expansion connector on the Link G4X board is provided to allow the easy connection of additional ECU inputs. The expansion connector provides the following:


  • 5V Supply
  • Sensor Ground
  • 3 Analogue Inputs
  • 3 Digital Inputs
  • 4 Ignition Aux Outputs (Direct Spark Ignition Option)


These may be used for functions such as driver adjustable boost control, switchable fuel/ignition maps, wideband lambda input, external MAP sensor, fuel pressure and oil temp/pressure. 

An ignition expansion is provided allowing you to convert to a Direct Spark ignition system. Alternatively these outputs can be used to drive auxiliary devices.



In addition to the ECU which can be purchased separately, we also offer the following packages:

Basic ECU Package:

Turbo ECU Package:

Please select the appropriate package from the drop down menu.


WARNING: Some models of ST185, particularly the ST185RC (Carlos Sainz Edition) do not use the ST185 ECU pinout. Instead the MR2Link V2-3 ECU must be used on this model. Please refer to the vehicles actual wiring and the pinout diagram in PC-Link, and the MR2Link V2-3 manual to determine which ECU should be used. Please contact us if you require any assistance in determining which model you require.


Additional information

Weight 900 g

Part Type



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