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Delta-Load Fueling Compensation

This is highly experimental.

(If it proves to be accurate, it will be added to the official ROM definitions.)

What follows is a condensed version of this thread in the ECU analysis forum.

The ECU’s calculation of “Final Fueling Base” contains a few compensations that are added to the primary fueling enrichment. One of those compensations, here dubbed Delta-Load Compensation, or “DLC,” is responsible for an excessively rich condition during spoolup.

The DLC parameter itself is calculated from four input parameters:

Input AChange in load since the previous iteration (low-pass filtered)
Input BChange in load in the previous two iterations (clamped between −0.2 and +0.2)
Input CThis is a function of input B and two or three tables, see below.
Input DThis is a function of input A, one of two scalars, and a table.

Input A is multiplied by another value to become Input D. That ‘other value’ may be 0.1, 0.03125, or a value that depends on RPM. The conditions that determine the multiplier have not yet been studied.

Input B is turned into Input C through a series of operations, starting with the “Delta-Load Sigmoid” table, shown here…

The transformed Input B is then scaled by one or both of the tables shown below. The table on the left is always used; the table on the right is applied when load is falling rather than rising. The tables are “DeltaLoad Input C Rising Load Compensation” and “DeltaLoad Input C Falling Load Compensation” respectively.

Inputs C and D are each scaled by Engine Coolant Temperature (ECT) activation tables, and the resulting values are added together to get the delta-load compensation:

DeltaLoad Compensation = (InputD * InputD_Activation) + (InputC * InputC_Activation)

InputC_Activation is strictly a function of ECT, and there are separate tables for rising load and falling load (rising is on the left in the picture below).

InputD_Activation also has rising-load and falling-load activation tables. The rising-load activation table is a function of both ECT and load (grams of air per combustion charge). The falling-load activation table is a function of ECT alone.

The ECT axes on the tables below are in Celsius.

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Page last modified on August 23, 2011, at 01:43 AM
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