by Stephen Dean on Fri Nov 06, 2015 10:23 am
Hi Brian,
Essentially the DC on a DI engine being run by an M1 changes based on available injection time, and the Actual Pulse Width at one load site will not relate to the Actual Pulse Width at another load site, even if they have the same DC.
From the M1 Help
Current fuel injector duty cycle as the ratio of the injection angle related to the maximum available injection angle.
The injection angle is calculated from:
•The maximum of Fuel Cylinder N Primary Output Pulse Width 1
•Engine Speed
The maximum available angle for an injection ensues as the difference between Fuel Timing Primary and Fuel Timing Primary Limit.
If the duty cycle comes near 100% this means the whole span between Fuel Timing Primary and Fuel Timing Primary Limit is needed to deliver the fuel. To avoid truncation of the injection, either Fuel Timing Primary or Fuel Timing Primary Limit can be extended to allow for a longer injection, however this must be done with care to not exceed physical limitations of the engine. Apart from using injectors with a higher flow rate also a higher fuel pressure can shorten the injection itself.
In transient conditions this value can be significantly higher than in constant conditions due to temporary compensation of fuel film effects.
Stephen Dean
MoTeC Research Centre Melbourne, Australia