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Pulse width

EFI Tuning Fundamentals

Discussion and questions related to the course EFI Tuning Fundamentals


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According to formula told in the videos if we put the values the pulse width comes independent of RPM. I am attaching a picture.

Picture is attached below.

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Remember some of the terms of your equation are really functions that themselves depend on RPM to some extent. For example Mass Airflow is not just EngineVolume x RPM / 2 for all RPMs or Throttle Positions (which changes Manifold Pressure). This function is the volumetric efficiency function of the engine, and this is what we tune to match the particulars of the intake / exhaust / camshaft mechanical system.

The change in volumentic efficiency will require a change in Fuel Flow Requeired, which means the Pulse Width of a single injection event will change.

You have reduced the formula for pulse width down to a single point of operation (ie, a single table value within the Fuel Map or VE Map).

Yes David I remember from the video that after this base pulse width we always have to use the correction factor as we assume VE to be 100%. But I thought that this base pulse width would be different for different RPM at full load and then VE comes to play when adjusting pulse width for different load of the same RPM.