Haltech F10 - Manual (Page 79)

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Boost Limit
If the manifold pressure exceeds this limit, the solenoid valve will immediately be set
with a duty cycle value of 5%. This will allow the full manifold pressure to act on the
waste-gate actuator and force the waste-gate to open. This value should be set slightly
higher than the desired boost pressure as a fail-safe in the event of an over-boost
condition.
Update Engine Data
This field allows the waste-gate duty cycle to be displayed on the engine data page.
WARN ING:
WE STRONGLY RECOMMEND THE USE OF THE OVER-BOOST
FUEL CUT FEATURE DESCRIBED IN THE FUEL SET-UP PAGE
INSTRUCTIONS (REFER 3.1.2 FUEL SETUP, 28).
16.2.3 Using the Boost Controller
The F10 has a “Trim Input” that can be used in conjunction with the Haltech
TM
Trim module
for boost control (Refer 13.1.1 Trim Control and Spare A/D, 61).
In normal operation the F10 uses the appropriate bar from the active TWG map (map 1 or
map 2) to drive the TWG solenoid. If the trim module is connected and set for “Boost
Control” the duty-cycle used to drive the solenoid will be the multiplication of the TWG map
value and the trim position.
For example:
If the active TWG map value was 60% and the trim module was set to 40% the actual
duty-cycle driving the TWG solenoid will be 24%.
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.
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.