Haltech E6K - Manual (Page 98)

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cycle will be taken directly from the Standard Boost Map. As the controller is rotated anti-
clockwise, the duty cycle is linearly reduced to 0%. When the controller is rotated clockwise
from the centre position, the duty cycle is linearly increased to the value in the Maximum
Boost Map. The Maximum Boost Map should always contain values greater than or equal to
the corresponding values in the Standard Boost Map.
The use of two independent boost maps allows an engine to be set up for maximum boost
conditions, but driven safely at lower boost pressures without the need of re-loading maps.
The boost controller may be used by the driver to match the engine's power output to the
current demand: higher boost pressures for qualifying speeds, lower boost levels for engine
preservation or wet roads.
If time constraints do not permit the complete mapping of the TWG function, waste gate
control may be executed from just one map. Select the Maximum Boost Map as the primary
map and the Standard Boost Map is never accessed.
16.3 Bypass Air Control (BAC) Valve
16.3.1 Description
The BAC is a PWM output allowing you to use a valve to operate Idle Air Control.
Traditionally, Idle Air Control (IAC) motors have been used but require knowledge of either
how many steps they have or experimentally finding the correct operation. BAC valves only
require a period (ms) setting as opposed to the number of steps, min steps in, max steps out,
etc as required with stepper motors. The period in milliseconds is the operating frequency for
the particular valve/solenoid. This frequency can be approximated but an accurate value will
help by giving the best response times. Consult factory information on your
particular/solenoid valve if the operating frequency is unknown: a typical value is approx
10ms.
The operation is fairly straightforward: each BAC solenoid/valve will have its own operating
frequency. By continually operating the valve at this frequency, you can then vary the duty
cycle to move the valve in or out. The duty cycle will therefore vary from 0 to 100% whilst
the operating frequency is maintained constant.
16.3.2 Using BAC Valves/Solenoids
The BAC settings are mostly done in the Idle Air Control section on the Output Options Page.
Firstly, set a PWM output to operate as BAC and set the operating period. Then go to the
Output Options Page. Select the Idle Air Control. Note that the Idle Speed will be disabled
because you are using a BAC output to do Idle Control and not an IAC Stepper motor. Go
through the settings as you would do if you were configuring Idle Control for a stepper motor.
A full description of the procedure is available in Section 14.2. Remember that you are using
a BAC valve/solenoid and not a stepper motor so not all of the settings in 14.2 will relate to
BAC.