MoTeC M1 Software Tutorial: VE-Based Fuel Model
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VE-Based Fuel Model
01.51
| 00:00 | A VE based fuel model, unlike a millisecond based fuel model actually defines the engine’s volumetric efficiency, or how effectively it is able to fill its cylinders with air at each combination of RPM and load. |
| 00:14 | Using this type of fuel model, the ECU is calculating the actual mass of air entering the engine and this gives the ECU a lot more control over the fuel delivery as we will see. |
| 00:26 | With a VE-based fuel model, the ECU starts by looking at manifold pressure, ambient pressure and engine speed to define where in the efficiency table the engine is operating. |
| 00:37 | Once it knows the engine efficiency, the ECU then takes looks at the engine displacement and number of cylinders to calculate the mass of air entering the engine. |
| 00:48 | The next step is to look at the mixture aim table for the desired air fuel ratio. |
| 00:54 | Now using the stoichiometric AFR and density of the particular fuel, the ECU can calculate the required fuel volume to achieve the desired air fuel ratio. |
| 01:05 | Lastly the ECU will look at the injector linearisation tables to decide on the final injector pulsewidth. |
| 01:12 | With a VE based fuel model, we are tuning the efficiency table rather than the fuel table. |
| 01:18 | This efficiency table will have a similar shape to the fuel table in a conventional millisecond based fuel model, but with numbers slightly higher than 100 around the area of peak torque. |
| 01:31 | The shape of the efficiency table however will be unaffected by fuel pressure or desired air fuel ratio. |
| 01:38 | With a VE based fuel model, changing the injectors or fuel pressure requires these new parameters to be entered correctly, but once this is done, the tune will not be effected. |
