Haltech F9A - Manual (Page 35)

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Chapter 4
Adjusting Haltech Maps
The tutorials presented in this chapter are examples of how you might use the available
functions to make typical modifications to the maps. These tutorials are aimed at explaining
both why and how some typical changes might be made. They assume that you have the
software running Online on your PC, with the ECU powered and connected via the supplied
programming cable.
4.1 What are maps?
The injection times needed by the engine at different conditions is stored by the F9 in a table
of numbers called a look-up table. The F9 determines the engine's load and speed, and uses
these two parameters as an index to the table. This table is called the Fuel Map. For
instance, at an engine speed of 4000 rpm and at -20kPa, the relevant number in the table
may be 4.35. If the engine approximates -20kPa at 4000 rpm, then the computer will extract
the value of 4.35ms from the table as the base injection time. This value is then adjusted to
compensate for numerous conditions, such as temperature or acceleration, and then the ECU
holds the injectors open for that time on the next injection.
It is possible to programme the F9 by directly changing the value of each number by
programming in the numerical mode, but this can be extremely difficult, so the Haltech
allows you to change the numbers by manipulating graphics in maps presented as bar
graphs. (This is much simpler and allows you to visualise the map)
Since it is difficult to interpret all the table's values at once, the programming software
divides the map by engine speed into a series of rpm ranges. Within the range, each load
point is represented by a vertical bar. Thus, when you view a range from the Fuel Map, you
see a bar chart of injection time versus load for all the load points in the table at that speed.
There are other tables in the F9, such as those used for temperature corrections. They are
indexed by only one parameter, and so are not divided into ranges. These tables are also
called maps.
4.2 What is mapping the Engine?
Mapping the engine is filling the look-up tables with the correct values for your engine. This
is done by adjusting the heights of the bars within the maps. Bars may be adjusted one at a
time, or in groups. The Haltech programming software has been designed to make engine
mapping as simple and intuitive as possible.