Delphi Multec 3.5, Руководство по применению

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Software Multec 3.5 Fuel Injector Application Manual
5-8 Delphi Energy and Chassis Systems
Revision: 11/05-1
fuel flow at small pulse-widths. The correction effectively extends the
dynamic range of the fuel system by decreasing the minimum usable
pulse-width. (See section 3.10.2)
Most software can correct pulse-widths of approximately 3.9 ms and
lower. (This correction varies with the control software.) Some software
contains a table bias term, which is another variable that allows the table
to correct for rich, lean, or rich and lean flow deviations.
Note Cylinder to cylinder flow variation increases as pulse-widths become very
short.
A very low pulse-width, such as during hot idle, is non-linear but it can be
corrected, using the low pulse-width correction. Low pulse-width
corrections are independent of voltage corrections.
Values for the correction table are obtained by flowing an average system
or several systems at the values of the table plus the injector offset using
characterized, mean-limit injectors (Flow point = table value + X intercept
@ 13.5v). For non-vacuum biased systems, this flow test should be made
at a manifold vacuum that is representative of injector low pulse width
operation conditions.
Note
This is necessary because the table corrects the BPW and not the total
pulse-width. In other words, the low pulse-width correction is done
before the injector offset is added-in, and this is done to correct the total
output pulse-width.
5.2.2.4 Low Voltage Correction
Low voltage correction is required as system operating voltages decrease
below the normal operating range. As operating voltage decreases,
injector opening response increases resulting in reduced fuel flow. Pulse-
width (PW) is increased to compensate. A software correction table is
calibrated for this use.
Flow changes due to voltage change are converted through the offset value
(refer to Figure 5-2). These flow changes are a non-predicted deviation
from the actual regression line, which become a simple table of correction
versus predicted values. It is necessary to normalize pulse-widths to
assure a smooth transition. Several spreadsheet programs have been
written to automate this entire process and are highly recommended.
5.2.2.5 Minimum Pulse-Width (MPW)
Minimum BPW is a user-defined point below which the injector will not
be operated. This is typically defined as a point where the actual injector