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Smart Tuner SMT8 - Turbo Fueller Application | Application Note : AN 1.7


Perfect Power Application Notes.


Application Note  - AN 1.7


This application note describes how to use the SMT8 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 Installation

Follow the steps below to install the SMT8.
  • Locate a cool, dry place under the dashboard, which has easy access. Make sure that you can reach the computer connector, when wire up the unit as per the diagram below :
SMT8 Piggy-Back Unit - SMT8 Installation Wiring
Note : The SMT8 has 3 drivers, each capable of delivering 1 amp maximum. This means the lowest impedance injector you can use is 1 x 13ohm for each driver. Only two extra injectors can be used as the SMT8 has two injection tuning maps. The third driver is normally used for boost control or as a switch light. 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 Analog channel is used as to "clamp" the max voltage from the AFM or Map sensor during boost.
  • 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.


SMT8 Injection Setup

On the left is the setpoint screen where the injector outputs is assigned. The driver no : 1 has been assigned by selecting pin 7 of 10 W1. Injection #1 is mapped on the F1 tuning screen. Injection #2 is mapped on the F9 screen.


SMT8 Piggy-Back Unit - Injection Setup

The two extra injector Maps can be mapped as one by ticking the "op inj#2 from #1" in the Shift F2 Map.
SMT8 Piggy-Back Unit - ShiftF2 - System Definition
SMT8 Piggy-Back Unit - F1 - Injection Map #1
The main Injection Map (16x24) is added to the air and engine temperature (1x24) side maps and is then multiplied by the AMP side map (1x24). Both injection maps work the same way and have the same side tables.
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 hte Fuel AMP column increases (as shown above). 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/s was adjusted. By utilizing the manifold pressure the injectors only need to be tuned under boosted conditions. It is easy, neat, produces a very smooth ride and is excellent for fuel control.