The Digital Fuel Optimizer...
The Digital Fuel Optimizer (DFO) from Custom Chrome is an add-on pot-type EFI controller that allows the tuner to change the engine's fuel curve with a screwdriver.
Conversely, EFI is rather hypothetical and shadowy because it uses complex computers, obscure "black boxes," and mysterious injectors to control an engine's fuel supply. In comparison to a carbureted engine, an electronic fuel-injection system mounts a throttle body instead of a carburetor to the intake manifold. The throttle body, also known as a TB, looks similar to a carburetor and includes a butterfly to regulate airflow, but it has no jets or float bowl to store fuel.
A TB's main function is to regulate air. Two electronically controlled fuel injectors (one for each cylinder) are mounted into the intake manifold and control the fuel supply. An electronic control module is mounted either under the motorcycle's seat or under the cover located on one side and just below the seat. The map-based ECM receives information from several engine sensors and, based on its map, sends instructions to the fuel injectors as to when to start and how long to spray (pulse width) fuel into the intake tract, while the TB butterfly regulates the air supply.
Instead of using tangible jets and simple screwdrivers for tuning, EFI requires complex computers for creating baffling fuel maps, which control the amount and the timing of the fuel supply by the injectors. As a tuning option, a simplified add-on "black box" is sometimes connected inline between the ECU and fuel injectors. The add-on black box intercepts the stock ECU signals to the fuel injectors and replaces the signals with modified instructions for the correct fuel delivery.
Dynatek's F.I. Controller...
Dynatek's F.I. Controller is an add-on device that allows the tuner to both richen and lean the fuel mixture using a screwdriver. The unit is supplied with three base maps.
Now that you have a brief understanding of EFI, let's take a look at some of the EFI tuning aids available to the engine builder and tuner to help eliminate the dreaded popping, stumbling, surging, pinging, flat spots, and overheating sometimes encountered with modified EFI engines. Tuning aids for Harley-Davidson's EFI systems can be divided into three major categories:
* Downloadable maps (called ECM calibration by Harley)* Add-on modules* Map-based reprogrammers (an add-on module may or may not be used)
Downloadable MapsHarley-Davidson and several aftermarket performance parts manufacturers offer downloadable maps designed for a specific engine parts combination. Harley calls its downloads "ECM calibration" and has several different calibrations for various Screamin' Eagle Stage I and Stage II performance kits. Harley's ECM recalibrations are specifically designed for engines equipped with Harley-supplied EFI systems (Delphi or Magneti-Marelli). Basically, you buy the recalibrated fuel map from a Harley dealer and then pay a small labor charge to have it downloaded into your ECM. Additionally, some makers of aftermarket EFI performance parts offer downloadable fuel maps from their websites for specific engine combinations.