3.10.2 Working Flow Range - Delphi Multec 3.5 Applications Manual

Multec 3.5 Fuel Injector Application Manual

3.10.2 Working Flow Range

Note
Delphi Energy and Chassis Systems
Working Flow Range is a measure of injector-to-injector flow variation
based on a production population of at least 24 injectors. It impacts
cylinder-to-cylinder air/fuel ratio.
Working Flow Range = Maximum flow divided by the minimum
For vehicle calibration, the working flow range and linear flow range
should be obtained from the fuel rail assembly flow.
Both linear flow range and working flow range need to be understood to
predict the injector behavior at a commanded pulse width. Some
calibration schemes can compensate for the non-linearity of the injector
with a low pulse width correction table. This assumes the injector
working flow range low pulse width is less than the linear flow range
lower pulse width.
The 5% value used for the calculation is a standard based on the SAE
J1832 specification. The percent deviation value used in the calculation
can be varied based on the recommendation of the vehicle calibrator for
the maximum acceptable cylinder-to-cylinder fuel variation. The injector
working flow range in combination with the rail round robin test to
measure cylinder-to-cylinder rail flow effects, can be used to calculate the
fuel system cylinder-to-cylinder fueling error. Unless the engine control
system has individual cylinder fuel control capability, this cylinder-to-
cylinder fueling error cannot be compensated for by the engine control
system. (Using the +/-5% standard limits translates into ~ 1.5 A/F ratio
total variation worst case.)
flow where all injectors are within +/- 5% of
the mean flow curve at 3 standard
deviations. Refer to Figure 3-18.
Product Description
Revision: 11/05-1 3-33