EPC-250 IOI 6-18 All rights reserved © ALTRONIC, LLC 2018
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9.1
Air/fuel ratio is controlled by regulating the air/fuel pressure ratio. A waste
gate (by-pass valve), in parallel with the turbocharger, is opened or closed to
decrease or increase the air manifold pressure. The desired air manifold pres-
sure is a function mainly of fuel pressure. The actual measured air manifold
pressure is compared to the desired calculated value and a signal (4-20mA) is
sent to the waste gate to compensate in the proper direction.
When replacing an EPC-200, enter the existing three point values of the air/
fuel curve by pressing the Legacy Curve button.
All the performance curves are entered into the EPC-250 Controller simply by
entering the (x,y) coordinates of each point of the seven line segments. In the
legacy configuration Channels 67 and 68 correspond to the first point (x =
fuel, y = air), Channels 69 and 70 automatically become the fourth line seg-
ment, and Channels 71 and 72 determine the end point of the curve. Pressing
the Calculate button automatically calculates the curve using the three points
of the 3-line segment of the legacy EPC-200 application and generates the
the required coordinates to complete the linear 7-segment curve. The air/
fuel ratio for that particular line segment is also calculated for each segment
which can be manually adjusted by clicking on the desired value. The program
also has the capability of linearizing the curve based on two known values
