Haltech F9A - Manual (Page 88)

87
5.1 Turbo Waste Gate Control (TWG)
The wastegate of a turbo is operated when the manifold pressure is sufficiently high to force
the diaphragm within the wastegate unit. With electronic boost control, the object is to use a
pulsating solenoid to bleed off the manifold pressure signal seen by the waste gate unit so that
it can see only a fraction of the manifold pressure. The solenoid operates at constant
frequency and the duty cycle is altered to control the drop in pressure signal through the
device.
In order to use the Turbo Waste Gate Control function, you will need the following:
- an F9A secondary harness incorporating the Auxiliary I/O connector
- a suitable pressure solenoid valve;
- air hose and fittings;
- F9 programming software and cable;
- an over-boost relief valve (strongly recommended).
The air circuit to the waste gate must be configured appropriately, as in figure 5.1-1. If it is
not directly filtered, the air bleed line to the solenoid should run to the airbox or into the car
body, free from road dust. Install the solenoid valve securely, and power and signal from the
Auxiliary I/O connector on the harness. The wastegate should be re-set so that its operation
point is very low, around 20kPa (3 psi).
NB: Be sure to use air hose that is rated to the pressure the engine is expected to be boosted
to. All fittings should be secured so that they will not disconnect under high pressures.
A relief valve should be fitted to the manifold as a backup in case of an air hose failure and
uncontrolled boost.
Figure 5.1-1. Diagram of Turbo with Wastegate Control Solenoid.