AEM 30-71XX Infinity Stand-Alone Programmable Engine Mangement System Full Manual User Manual

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Infinity User Manual

The example below is a boost strategy for a high horsepower, severely traction limited drag car
that runs on varying mixes of Ethanol. Boost compensated for changes in baro pressure
(weather, altitude, etc) and changes in exhaust backpressure. Typically, higher duty cycle is
needed to retain boost level as baro pressure is reduced and EBP is increased. However, due
to the Infinity's advanced PID system, you could theoretically get away without having these
sensors and still have consistent boost control by relying on boost feedback.

Failsafe strategies include injected pressure (this is the pressure delta between the fuel pressure
and manifold pressure). On a manifold-pressure-referenced fuel pressure regulator, injected
pressure should theoretically remain constant at all times, as the pressure regulator directly
combats changes to manifold pressure by changing fuel pressure in a 1:1 ratio. However, if there
is a pressure regulator failure, or a fuel flow issue (weak pump, restricted lines, etc) injected
pressure can drop. The boost control is set up to automatically reduce boost in this condition.
Side note: Due to the Infinity's model-based fuel calculations, any variation in injected pressure
will also be compensated for in fueling.

You'll notice that the boost target increases with each gear, as it should. Also, with higher Ethanol
contents, more boost can be run safely, but of course we only want this in the higher gears as
we're traction limited. However, it was found on this car that higher ethanol contents (at the same
boost level) caused an increase in torque due to the fuel/tuning, and this caused additional wheel
spin. Therefore, boost target is actually reduced slightly in lower gears and higher ethanol
contents to combat this tendency.