This option determines how the load input to the fuel equation is derived. The load signal is an estimation of the pressure forcing air into the cylinder.

 

Equation Load Source has the following options available:

 

·Load=MAP - Manifold Absolute Pressure (MAP) is used as the load input for the fuel equation. This means that when the manifold pressure doubles, there will be twice the cylinder charge. This is the preferred mode and should be used on all applications unless the MAP signal is not a reliable reference to manifold pressure.

·Load=BAP - Barometric Absolute Pressure (BAP) is used as the load input for the fuel equation. This allows for correction of the estimated air charge based on barometric pressure. This can only be used on naturally aspirated engines with no useable MAP signal.

·Load=BAP/MAP XOver - BAP is used as the load input for the fuel equation while the MAP value is less than the BAP value (ie manifold vacuum). When MAP is greater than BAP (ie under boost), MAP is used as the load input to the fuel equation. This mode is rarely used but can have application on forced induction engines with a very weak or erratic MAP signal when in vacuum.

 

Further Explanation of Equation Load Source Options:

 

·Load=MAP - This is the most common mode used. In this mode Manifold Absolute Pressure (MAP) is used in the main fuel equation. This means that a doubling in the MAP reading will result in twice as much air charge and hence twice the fuel being delivered to the engine (assuming the main fuel table number stays constant).
In order to get Barometric Pressure Correction into the fuel calculation in this mode, the Fuel Table Load Axis should be set to MGP.
For engines with low manifold pressure, or one throttle butterfly per intake port and turbocharged, set the Fuel Table Load Axis to TP(Main).

·Load=BAP - This mode is used on more aggressive engines where the MAP reading is too low or inconsistent to provide stable tuning.
In this mode the Fuel Table Load Axis will typically be set to TP(Main).
This mode then effectively provides barometric pressure correction for engines 'mapped off TPS'.

·Load=BAP/MAP XOver - This mode is a combination of the Load=MAP and Load=BAP modes. Under vacuum, the fuel equation uses Barometric Absolute Pressure (BAP) but changes over to use Manifold Absolute Pressure (MAP) under boost. This results in a calculated fuel addition once under boost.
The best way to use this mode is to span the main Fuel Table Load Axis with TP(Main). Enable the 4D fuel table and span its Load axis using MGP. Set the Load Axis to start at 0 kPa and ensure that all numbers in the first row are 0. This gives BAP correction over the entire operating range and allows fuel tuning under boost.

 

Setup Examples

 

·Naturally aspirated engine with stable intake manifold pressures.

·Equation Load Source - Load=MAP

·Fuel Table Load Axis - MGP

 

·Naturally aspirated engine with unstable intake manifold pressures.

·Equation Load Source - Load=BAP

·Fuel Table Load Axis - TP(Main)

 

·Turbo/Super charged engine with stable intake manifold pressures.

·Equation Load Source - Load=MAP

·Fuel Table Load Axis - MGP

 

·Turbo/Super charged engine with unstable manifold pressures below atmospheric pressure.

·Equation Load Source - Load=BAP/MAP XOver

·Fuel Table 1 Load Axis -TP(Main)

·4D Fuel Table Load Axis - MGP