The Fuel Charge Cooling Coefficient number is used to determine the cooling effect the evaporation of the fuel has on the temperature of the air charge. The amount of charge cooling is determined by the latent heat of evaporation of the fuel, the manifold air temperature, the injector location and spray pattern and various other complex factors. Determining this number mathematically is complex and it is more simple to determine it during tuning.

 

This is an important correction and greatly improves the fuel calculations ability to deliver the expected target Lambda value. Tuning of this setting also relies highly on accurate injector information (particularly dead times) being entered first.

 

WARNING: Changing the Fuel Charge Cooling Coefficient after the Fuel (VE) Table is tuned will alter the engines tune. This number must be set before final tuning and not changed.

 

If you do not want to use the fuel charge temp cooling correction, set this setting to 0.

 

A Typical setting is 10 deg C for gasoline.

 

Typical Procedure for Setting Fuel Charge Cooling Gain

1.Make sure all fuel settings and injector characteristic information is correct.

2.Tune the engine well enough that it can be safely operated in the mid RPM/load area.

3.Pick a particular RPM/load where the engine can be held reasonably steady.

4.Set the Lambda Target in all cells around the area to be tuned to a value of Lambda 1.0. Hint, use the U key to toggle between AFR and Lambda display).

5.Tune the cells in Fuel Table to make the measured exhaust lambda read a stable Lambda 1.0.

6.With the engine running steadily at Lambda 1.0, adjust the AFR/Lambda Target to 0.9.

7.If the exhaust Lambda is less than the Lambda Target (too rich) then reduce the Fuel Charge Cooling Coefficient number. Otherwise if the exhaust Lambda is higher than the Lambda Target (too lean) then increase the Fuel Charge Cooling Coefficient number.

8.Change the AFR/Lambda target back and forwards between 1.0 and 0.9 adjusting the Fuel Charge Cooling Coefficient number until the exhaust lambda matches the AFR/Lambda target.

 

Note: This setting is only used when the Fuel Equation Mode is set to Modelled or Modelled - Multi Fuel.