In Speed/Density mode, the base fuel table will appear as a 3D table of intake manifold pressure in kilopascals (kPa) vs. engine RPM.  The table will be labeled "Volumetric Efficiency vs. RPM and MAP".  In Alpha-N mode, the base fuel table will appear as a 3D table of throttle position vs. engine RPM.  The table will be labeled "Injector Pulsewidth (mS) vs. RPM and TPS".

The base fuel table should be calibrated in one of two ways:

• While operating in closed loop mode, adjust the values in each cell so that the O2 correction values are as small as possible while operating within that cell.

  C-Com WP versions 1.015 and later have a helpful utility for calibrating the VE table when operating in closed loop mode.  By pressing the "L" key, the amount of correction currently being applied by the closed loop routine will be applied to the value of the cell in the VE table you are currently using.  For example, if you are operating in a cell in the VE table with a value of 60 and you see that there is a 10% O2 correction being applied, pressing the "L" key will apply the 10% correction to the value in the VE table.  The end result is that the cell that was reading 60 will now read 66, and the O2 correction will be very close to zero.  Please bear in mind that this utility is meant to be used only in a "steady state" mode.  You should also only use this utility when the floating cursor is centered within a single cell.  If the cursor is being influenced by surrounding cells, if the engine speed or load is changing, or if any acceleration enrichment fuel is being applied, the results of using this utility may be well off of the intended result.

   

• While operating in open loop mode, adjust the values in each cell so that the actual measured air/fuel ratio matches the target air/fuel ratio as closely as possible.

There are a few general guidelines to keep in mind when calibrating the base fuel table: 

• Higher numbers in the base fuel table mean more fuel, and vice versa.
• With a properly calibrated base fuel table, the cell values should be highest at the engine’s peak torque RPM and then decrease beyond peak torque.  In Speed/Density mode, the highest numbers are typically in the 90 to 100 range on naturally aspirated engines.  On forced induction applications, it is common for VE numbers to be in the 110 to 120 range.
• Calibrate the base fuel table while the engine is at its normal operating temperature.  Warm-up enrichment while the engine is cold could cause your calibration to be off once the engine is fully warmed up.
• A good calibration should result in no more than 5% O2 correction (or deviation from the target air/fuel ratio) anywhere within the normal operating range of your engine.  
• By pressing the "G" key when the base fuel table is open, a 3-dimensional graph of the table will be displayed.  There is a very general "shape" to the graph that almost any proper calibration will produce; the following illustration shows this shape.  The blue area in the graph is the idle region of the map, and the red area is the wide-open throttle area.  The RPM where the highest VE or pulsewidth values are should correspond to the engine's peak torque output; if you are tuning on a dyno and can monitor torque output over the RPM range, this is an excellent indicator of a correct calibration.