AEM 30-6905 Universal Programmable EMS-4 - Manual (Page 263)

Page 263 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
Tuning Staged Injection
First, confirm that all of your primary injectors are defined properly. They must be "active" as
well as defined as either Primary or Secondary. To do this, go to the Coils/Inj tab:
In the example above Injectors #1 and #2 are defined as Primary and Injectors #3 and #4 are
defined as Secondary.
You need to define where, in the engine cycle, you want the staged injectors to begin their
injection pulse. This is set in the same manner as primary injectors and is done with the option
Injector Phasing settings above. This value is in crankshaft pickup teeth (a.k.a. fuel teeth) after
TDC #1 compression. This value is proportional to degrees of crankshaft rotation. It is actually
quite helpful to understand that the EMS actually counts the number of crankshaft teeth passing
until it gets to this number and then starts injection.
For a 12 tooth crank trigger wheel on a 4 stroke engine, there are 24 teeth per cycle (numbered
0 to 23.999). If the Inject Tooth #6 was set to 6.5 teeth, that would tell the EMS to let 6.5 teeth
pass (720/24 x 6.5 = 195 crankshaft degrees into the cycle)and then activate Injector #6. It is
important to note that this is not the final injection location, it is just a reference point. All primary
and staged injectors are under control of the Inj Advance Map, which is a load vs. engine
speed table that is used to set the actual injection phase.
The flow rate difference between the primary and staged injectors is necessary to accurately
distribute the required fuel between the two different delivery systems. It represents the percent
of primary injection time needed to flow an equivalent amount of fuel from the secondary
injectors and is entered in the Staged Flow Ratio option.
Staged Flow Ratio = ((number of primary injectors x primary flow rate) / (number of secondary
injectors x secondary flow rate) x 100) - 100
Remember, this is not simply the flow ratio between the 2 different injectors, it factors in the
number of injectors as well. This number can range from -100 to +100. AEM Tuner includes a