Haltech F10 - Manual (Page 95)

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flow is not in direct proportion to fuel pressure. Increasing fuel pressure will increase injector
dead time and reduce the flow rate of the pump.
C.3 Injector Staging
Another way of increasing injector flow, without compromising good drivability and fuel
economy is to employ staged injection. Injector staging allows the use of primary and
secondary injectors and is usually only used on high boost turbo or supercharged engines. The
ECU will fire only the primary set of injectors until a preset load point, where the ECU will
control both primary and secondary injectors.
The turn on point for the secondary injectors depends on injector size and engine
performance, but will usually occur just after the pressure in the intake manifold of the engine
has reached atmospheric pressure. The staging point must occur before the primary injectors
have reached 100% duty cycle, go to the highest speed range in the fuel map that the engine is
using, and make sure that the last bar for primary injection is not too high. If it is, you must
stage at a lower pressure. (Refer 4.6 Duty Cycles, 38).
Adjust the bars around the staging point with extreme care to ensure that the engine does not
lean out as the secondary injectors come in. When the Haltech ECU begins to stage it begins
firing both sets of injectors at once and fires them with the same duration. This means that if
both primary and secondary injectors are of the same flow rate then the first staged bar should
theoretically be slightly more than half that of the last un-staged bar. Allow a safety margin by
using 60% of the last bar.
(Staging is enabled in the Fuel Set-up page; Refer 3.1.2 Fuel Setup, 28).
Once staging is enabled, the bars on the Fuel M aps will change appearance. The bars that
indicate both sets of injectors firing are a different colour to those corresponding to primary
injectors firing alone.
When staging injectors, drivers 1 and 2 (INJ1 and INJ2) are the primary drivers and drivers 3
and 4 (INJ3 and INJ4) are the secondary drivers. Since the number of primary drivers is
halved, and since you may wish to employ higher power secondary injectors, ensure that you
have sufficient driver power to run the injectors properly.
(Refer Appendix B
Fuel Injectors, 87)
C.4 Fuel Pump Capacity
You should ensure that your fuel pump is capable of supplying sufficient fuel to feed the
engine at maximum power. With the engine switched off (injectors closed) feed the return
line of the fuel pressure regulator to a measuring container. In the case of a turbo- or
supercharged engine, pressurise the manifold pressure port of the fuel pressure regulator to
the maximum boost of the engine. This is necessary as the flow rate of the pump decreases
with output pressure. Power the pump for one minute and calculate the hourly fuel flow rate
of the pump.