Fast 30400-KIT-EZ-EF Instructions Manual - page 49
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will be sent to the selected textbox. (For E85 applications, you may only need to enter two digits. For
example, enter “92” for a 9.2 air/fuel ratio.)
The ECU is constantly working to keep the air/fuel ratio at the current target air/fuel ratio. It is
preloaded with typical targets. This is where those targets can be adjusted if desired. Keep in mind that
a higher number means a “leaner” air/fuel ratio – less fuel. And a lower number means a “richer”
air/fuel ratio – more fuel.
Different operating conditions require different air/fuel ratios. The EZ-EFI
®
system distills these
different requirements down to three simple settings. Any of them can be adjusted while the engine is
running so different settings can be evaluated.
Idle AF – This is the target when the engine is idling. This can have a pronounced effect on
idle quality. It is worth experimenting with to see what your engine likes. If you notice the
engine struggle or if RPM dips considerably with load changes at idle (going into gear or
turning steering wheel to full lock, for example), it may prefer a richer Idle Air/Fuel target.
Cruise AF – Once the engine is above idle, it will switch to using this target. The engine will
spend the vast majority of its time in this area. This setting has the largest effect on your fuel
mileage. A leaner target (higher number) will use less fuel.
Because these settings are so simple to adjust, you may consider changing them for special
situations. If you are going on a long, relaxed highway run, you can temporarily set this a little
bit leaner to maximize fuel economy. Then set it back for normal around-town driving.
WOT AF – Once the engine starts to see more load (LOAD value around 50% or higher), the
ECU will start transitioning from using the Cruise Air/Fuel target to using this Wide Open
Throttle Air/Fuel target. By the time the engine is under full load, the ECU will be using this
target. For intermediate loads, the ECU interpolates between the Cruise and WOT targets. That
is, it changes its target from the Cruise setting to the WOT setting in proportion to how much
the load has changed from a cruising load to full load.