EfiMini Installation

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Basic Simplified Installation Description

Installing the efiMini electronic fuel injection interceptor device only requires a few connections. The following diagram illustrates the simplified installation schematic for installing the device between the vehicle's ECU and the injectors. Connections for the TPS and battery hookups are also shown.

EfiMini efiInstall.png


Connection Description
Ground A solid electrical ground to the motor vehicle's engine, body or battery ground terminal
+12V A switched 12 V power supply, preferably from the injector's 12 V rail or ignition lock.
TPS The throttle position sensor signal wire. See section TPS for details.
ECU Inj0-3 Outputs For a four-cylinder engine, the ECU will have four injector output wires. These connect to the efiMini's injector input connectors.
efiMini Inj0-3 Inputs These connections come from the ECU injector outputs.
efiMini Inj0-3 Outputs These connections, intercepted by the efiMini, go the the injector solenoids.

The efiMini sits between the stock ECU's injector signal outputs and the injector solenoids. This allows the efiMini to intercept the signal coming from the ECU so that the timings can be analyzed and altered.
When the ECU supplies an injector ON pulse to each injector solenoid, the signal has to pass through the efiMini before reaching the injectors.
In more detail : The injectors are typically supplied by the ECU with a 12 V rail. Now the efiMini provides the 12V rail along with it's internal load resistors on it's inputs to the ECU's outputs. When the ECU supplies the ground switched injector ON pulses to each injector output (efiMini input load resitors simulating injectors), the injector signal timing is recorded inside the efiMini before being timing adjusted output to the real injector solenoids.


Most throttle position sensors use a potentiometer that is mechanically attached to the throttle's butterfly valve shaft. The sensor generally has 3 connections:

  • Ground Wire
  • Constant voltage supply wire (generally 5 V)
  • The signal wire where the voltage changes with the throttle position between the supply voltage and ground.

Note : All published design documentation is Copyright efiLabs.com and its use is without exception FOR NON COMMERCIAL PURPOSE ONLY. For commercial licenses contact efilabs.com ... try us, we're reasonable :)

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