Dynalco AF-900PC Air/Fuel Ratio Controller - Manual (Page 44)

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14. Manifold Air Pressure Sensor (MAP) Load
Compensation (Option)
The AF-900PC is capable of accepting an input from a MAP sensor
in order to determine engine load. This option is needed for engines that operate
over a very wide load range and thus, one fixed post-catalyst setpoint does not
maintain emissions over the entire load range. If this option is used, the post-
catalyst O
2
setpoint is "offset" according to the engine load, which is proportional to
the MAP sensor output.
Up to ten offset points can be created for precise compensation in the high load
range. In the low load range, the base post-catalyst O
2
setpoint is used exclusive of
any offset. Only loads above "point zero" engine load (MAP) have any offset
added to the base post-catalyst O
2
setpoint. At all engine loads the base post-
catalyst O
2
setpoint never changes, but offsets are added to it once high engine
load compensation begins.
In order to add MAP offsets, the user must enter SETUP mode by pressing the
SETUP key. When prompted for a Password, enter "1 2 3 4 " (or the correct
password if it has been changed from the factory default), and press ENTER.
A "Zero Point" must first be entered. Point zero is the starting point for MAP offset
compensation to begin. The "Zero Point" is the largest MAP load where the engine
remains in compliance with zero post-cat offset. To program "Zero Point" proceed
as follows:
AF900PC
Simplified Control Software Block Diagram