Timing calculator location

[Dommyvee]

Ok am I missing something here? Where is the timing calculator on v8? Or is it the main injection timing table..and you adjust it to your liking?

[cindy@efilive]

It is all documented in the Dodge Cummins User Guide - pages 19 and 20. https://content.efilive.com/document...er%20Guide.pdf

Cummins Fuel Timing Calculator
To open the CFTC, click this icon in the tool bar:


The icon is only enabled when one of the fuel timing tables is displayed for editing.
When you open the CFTC window, the table is pre-populated with the correct percentages that are required to calculate the currently displayed timing table values. That allows you to evaluate the existing injection pulse timing. After you have made any changes to the CFTC table, click the [Apply] button. Applying the changes will update the underlying fuel timing table so that the injection pulses are delivered at the timing selected in the CFTC window.
Minimum %

It is sometimes required that the minimum timing does not fall below a certain percentage. In that case, check the Minimum % check box in the lower left corner of the calculator window. And set the minimum percentage value.
Setting that value will not change any values displayed in the timing calculator, instead it will simply force the calculator to compute timing values that are never less than the percentage value specified when the [Apply] button is clicked.
For example, setting the Minimum % to 5 will force the calculator to treat all cells’ values that are less than 5% as if they were 5% when computing the fuel timing.

How does it work

When fuel is injected, the injection pulse width is some number of micro seconds. Some tuners would like to set the fuel timing so that the injection pulse will start at a given crankshaft position relative to top dead center (TDC) of the piston.
The CFTC allows you to specify the percentage of the injection pulse width that will occur before top dead center (positive values), exactly at top dead center (0) or after top dead center (negative values).
For example, assuming the injection pulse width for a particular cell is calibrated at 500us (500 micro seconds), then the following percentages in the fuel timing calculator will result in the injection pulse starting at various crank shaft degrees for 1000rpm and 2000 rpm:

Fuel Timing %	Injection Start us	Degrees @1000rpm	Degrees @2000rpm	Relative to TDC
200%	1000	6.0	12.0	Before TDC
100%	500	3.0	6.0	Before TDC
50%	250	1.5	3.0	Before TDC
0	0	0.0	0.0	At TDC
-50%	-250	-1.5	-3.0	After TDC
-100%	-500	-3.0	-6.0	After TDC
-200%	-1000	-6.0	-12.0	After TDC

Looking at the second row, a percentage of 100% means that the injection pulse starts 100% of the pulse width before TDC. Since the pulse width is 500us, the injection start time should be 500us (100% of 500us) before TDC. At 1000rpm that would be 6 degrees before TDC, at 2000rpm that would be at 12 degrees before TDC.
Looking at the fifth row, a percentage of -50% means that the injection pulse starts 50% of the pulse width after TDC. Since the pulse width is 500us, the injection start time should be 250us (50% of 500us) after TDC. At 1000rpm that would be 3 degrees after TDC, at 2000rpm that would be at 6 degrees after TDC.
Related Tables

The CFTC uses values from two other related tables. Those tables will usually be different for each timing table. The names of the related tables are shown in the CFTC window’s description pane. If the values in those related tables are not accurate then the calculator may not produce accurate results. For example, if you were working with the timing table E2503, the related tables are: {D0508} "Injection Pulse Conversion" and {D0782} "Fuel Pressure, Base". The first column of data in {D0508} may be calibrated to be all zeros which will cause this calculator to set the corresponding first column of data in {E2503} to be all zeros.
You may prevent the calculator from adjusting any cells by selecting only those cells in this table that you want updated before clicking on the [Apply] button. If no cells (or all cells) are selected in this table, then the entire table will be updated.
Technical details

The CFTC computes the fuel timing percentages from the fuel timing degrees using the following equation:
% = t / (us * rpm * 0.00000006)
The CFTC computes the fuel timing degrees from the fuel timing percentages using the following equation:
t =% * (us * rpm * 0.00000006)
Where:

• t is the injection timing in degrees of crankshaft rotation.
• us is the injection pulse width in microseconds.
• rpm is the engine speed.