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injbatadj

InjBatteryAdj

In the direct access area of ECMLink, there is a table called InjBatteryAdj. This table is indexed by battery voltage and provides an appropriate deadtime adjustment at the corresponding voltage. As voltage drops, injector response changes. Less voltage results in a “slower” injector and the need for more deadtime.

This page provides a simple explanation of how to “see” the effect of this table in your datalogs.

Before adjustment

The picture below shows a clip of a datalog where the power window switch was used to raise the windows until the windows were closed and then the switch was held a few seconds longer to produce a load on the alternator. As you can see, this dropped battery voltage and the mixture went lean as a result.

The following is the InjBatAdj table that was used. The injectors in this case were FIC 850s running at 43.5psi base fuel pressure.

Deadtime
Voltage (usecs)
7 2490
9 1530
12 1215
14 1020
16 930
19 825

NOTE: That list is total deadtime. To use with ECMLink, set the deadtime offset field on the Fuel tab to zero.

After adjustment

Based on the data from above, the 12-volt entry was increased by 150usecs. The 9-volt entry was also increased just to provide a “smoother” transition to the 7-volt entry. The result is shown in the image below.

The following is the table that was used.

Deadtime
Voltage (usecs)
7 2490
9 1905
12 1365
14 1020
16 930
19 825

NOTE: That list is total deadtime. To use with ECMLink, set the deadtime offset field on the Fuel tab to zero.

injbatadj.txt · Last modified: 2009/09/18 02:14 by twdorris