This article will describe the basics of mapping.
An EFI vehicle will have a computer or Electronic control module (ECM) that is programmed by the manufacturer of that vehicle to deliver the correct amount of fuel as needed.
The Screamin Eagle Race Tuner (SERT) is being used for an example:
The programmer will start by calculating the amount of fuel needed for every throttle position and RPM combination. He will then program the Volume Efficiency (VE) base map for each cylinder. The VE map is the basses that all of the other parameters will be calculated.
You can see that there are several other tables that are involved with supplying information to keep the correct amount of fuel at all times.
All of these tables adds or subtracts fuel from the VE map or table. This proves that the VE table is the base for all other tables to build upon. After the VE table is created by the programmer, the information in each cell is lowered before the table is saved and made the permanent VE base map. The reason for this is so the other tables will have the capability to lower the fuel trim of that table especially tables that are controlled by engine temperature.
The Air Fuel Ratio Table
If both front and rear VE tables are calibrated correctly (both having the same AFR in each corresponding cell), The AFR table is then programmed to provide the correct air fuel ratio desired. In theory, if you change the cells in the AFR table, then it will change both cylinders to what ever numerals that are in that cell. Example: If the cell at 50 MAP / 2500 RPM is 14.6:1, both cylinders should be 14.6:1 AFR. If that cell is changed to 13:1, then both cylinders should 13:1 on that cell. The 2007 and newer bikes, with O2 sensors will be in closed loop (the O2 sensors are turned on) in any cells that are changed to 14.6:1. If the cells are changed to any number below 14.6:1, the O2 sensors will be in open loop (turned off).
This table is controlled by the MAP sensor (Manifold Absolute Pressure). The MAP sensor measures the amount of vacuum or pressure inside the intake manifold. This will change the mixture according to the amount of load on the engine and also corrects the fuel mixture for different altitudes.
The Warm Up Enrichment Table
This table lets you add or subtract fuel according to the engine’s temperature. The engine has different fuel demands at different temperatures.
Cranking Fuel Table
This table will allow extra fuel to be delivered during engine cranking in relation to the engine’s temperature. Some engine builds (such as very large cubic inch engines) need a little extra fuel added while the starter is engaged.
The Accel. Enrichment table acts as an acceleration pump in a carburetor, supplying fuel when the throttle is opened quickly.
The Decel. Enleanment table adds or subtracts fuel for engine deceleration to keep the exhaust from popping.
The Tuning Constants tells the program what size the engine is, what size the injectors are and sets the rev limiter.
All of theses tables listed above add and subtract fuel from the front and rear VE table.
The Idle RPM table adjust the engine’s idle.
The IAC Warm Up Steps table lets you adjust the idle needed for different engine temperatures.
The older Power Commanders only had the ability to change the injector pulse of the VE tables. They also could change the ignition timing.
The Power Commander V (5) can read the ECM data being communicated and can now basically manipulate the injector pulse according to that data.