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18.6 Acceleration fuel enrichment and decay
Acceleration enrichment is a fuel increase when the throttle is suddenly opened.
Max fuel on pump: value added to the actual injection time when a quick throttle variation is detected. There are
two RPM and injection time parameters to be set. With them, the ECU creates an acceleration fuel table that interpolates
the values between these two positions.
TPS/MAP variation for maximum fuel pump: This configures the MAP or TPS variation for which the max fuel
pump will be used. For example, an engine running with only 10% of TPS at 1000rpm, suddenly, the TPS goes up to
50%. TPS variation was 40%. If the value set on this parameter is 40%, the max fuel pump for this RPM will be added to
the actual injection time. If, on the other hand, the TPS variation were only 20%, only half of the max fuel pump will be
added.
Engines equipped with small throttles usually need a higher TPS variation to need max fuel pump. In this case,
use higher TPS values on this parameter (70-90%). For big diameter throttle bodies, a small TPS variation is enough to
demand max fuel pump (around 15%).
Accel fuel pump reduction above TPS 50%: due to reduced need of fuel when the acceleration fuel pump
occurs with the throttle already opened above 50%, this parameter reduces the max fuel pump on this condition. By
standard, the ECU reduces 50% of the max pump when it occurs above 50% of TPS.
Cold engine fuel pump enrichment: this is a simple increase on the max fuel pump value when the engine is
cold, extremely needed on the first minutes of engine operation.
Fuel decay on max pump: this is the injection time that will be subtracted from the actual injection time during a
sudden throttle closure.
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