SM4 Manual
by
MRM-Racing
V3.0
25
Engine Cycles
Select either 4 Stroke or 2 Stroke or Rotary
Overall Fuel Calibration Multiplier
This value can be anything from 0 to 39.987
This is a value that is used by the ECU to determine the scaling to use on the values in
the Base Fuel Table.
For example: If the base fuel table has a value of 50 in any particular cell, the actual
amount of fuel injected into the engine will be a function of the injector size. A 50 Lb/Hr
injector would spray less fuel than a 160 Lb/Hr injector for the same value of 50 in the
table, so the Overall Fuel Cal Multiplier sets the scale for the table based on the
relationship between the size of your engine and the flow capacity of your injectors.
A good starting point for this value is to use the following formula:
8.112 * D/I
Where:
D = Cylinder Volume in CC’s
I = Injector Flow Rate in CC/min
After you have the engine tuned completely, the value in this table can be changed to
suit a new size of injector without re-mapping the engine by using the same formula.
Compression Ratio
It is important that you set the correct Compression Ratio for the engine.
The engine’s compression ratio affects the mathematical model of the engine created
behind the scenes in the Autronic software. An engine’s compression ratio has a direct
effect on its Volumetric Efficiency and if the wrong ratio is selected it is difficult to get the
proper correction factors needed for the software to make automated changes in fuel
accurately.
Clear Flood TPS
The default value of 90% TPS is normally okay for startup. This value represents the
percentage of throttle opening during cranking where the ECU will no longer provide an
injector pulse. This allows a flooded engine to be cranked over without adding any
additional fuel until it starts.
Ignition Setup
Next you will want to move to Ignition Setup menu under the M1 tab at the top of your
screen.
Under this menu you will select:
Ignition O/Ps
Press F1 in the software to see all the options.
Select the number of ignition outputs and the type of coil system that will be used.
Example:-
Four cylinder engine with four coils = 4cyl-MC
Four cylinder engine with two coils = 4cyl-WS
Six cylinder with three coils = 6cyl=WS
Six cylinder with six coils and using Multiplexer = 6cyl-Mux