OMEX OMEM710 - Page 28

OMEM710 Hardware Manual 2v11
28
This time period of no flow varies in length with battery voltage and with fuel pressure. This also
varies between injector models. Were an engine to run at a constant voltage, then there would be no
problems as the injector reaction time would be a constant length. However, the injectors do see a
varying voltage so the ECU needs to allow for this varying period of no fuel flow, and as all types of
injector react differently, it needs to be told this information by the user. The information is held in
the ECU in the Battery Comp table. Standard | Conditions Corrections | Fuel | Battery Voltage.
The battery voltage compensation data can usually be supplied by the injector manufacturers. For
example, the Weber IW 058 injector data is for 3bar fuel pressure,
Battery Volts
Offset time mSec
8.0
2.03
10.0
1.22
12.0
0.81
14.0
0.56
16.0
0.39
The Omex ECU can not take the data in the form of offset time in msec, it instead requires the table
to hold the data as a number between 0 and 255 which is then scaled. If using offsets from injector
manufacturers simply multiply the offset time, usually stated in mSec, by 100.
Battery Volts
Battery Comp
8.0
203
10.0
122
12.0
81
14.0
56
16.0
39
The missing values for odd voltages are best blended using the graphical display of View | Battery
Comp Table | graph
If this information is unavailable for your injector, then you will need to find these values yourself.
 Connect a power supply to run the injectors and ECU at variable voltages
 Set the voltage to one of the sites in the Battery Comp Table near to the normal running voltage
of the vehicle, typically 14V.
 Map an area of the fuel map to a constant AFR (this area should be out of idle so the engine is
steady)
 Change the voltage of the power supply to one of the voltages on the Battery Comp table
 The lambda reading may change. If so, change this voltage’s value in the Battery Comp table
to return the lambda to the original reading