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Smart Tuner SMT8-L - Turbo Fueller Application | Application Note : AN 2


Perfect Power Application Notes.


Application Note - AN 2


This application note describes how to use the SMT8-L as a TURBO FUELLER.


"Turbo Fueling" adds fuel to the engine via an extra injector. It is applied to Supercharged and Turbocharged engines and eliminates fuel starvation due to the increased airflow.

SMT8-L Installation

Follow the steps below to install the SMT8-L :


  • Locate a cool, dry place under the dashboard, which has easy access. Make sure that you can reach the computer connector, then wire up the unit as per the diagram below :


SMT8-L Piggy-Back Unit - Installation Wiring



Note : The SMT8-L has 1 injector driver, capable of delivering 1 amp maximum. This means the lowest impedance injector you can use is 1x13ohm. Should you need to drive lower impedance injectors see the application note "Power Amplifiers".


  • The AMP input (or "MAP" in some countries) is a signal from 0-5 Volts and should span the boost pressure. It can be calibrated to suit your application and it can be read in BAR or PSI.
  • The RPM signal can be from any pickup. It can be a missing tooth wheel or any other signal.
  • The Throttle position signal (TPS) input should describe the engine load. It is normally connected to a throttle sensor, but airflow or manifold pressure can also be used.
  • The MAP SWITCH is optional. It allows you to switch between TWO maps while you drive. For example, the one map can be used for power tuning, while the other map for fuel economy.


Injection 1 is mapped on the F1 tuning screen.


SMT8-L Piggy-Back Unit - F1 - Injection Map #1


The main 16x24 map is multiplied by the side AMP 1x24 side map and the air and engine temperature 1x24 side maps are added to the main map.


By making the AMP column zero, this would inject no fuel. This is usually done when there is no boost as the injector is not needed to pulse. To have progressive fueling under boost would require that the Fuel AMP column increases. This would in turn multiply the numbers on the screen, adding more fuel for higher boost.


In this application, only the fuel via extra injector was adjusted. BY utilizing the manifold pressure the injector only needs to be tuned under boosted conditions. It is easy, produces a very smooth ride and is excellent for fuel control.