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Injector Duty Cycle

EFI Tuning Fundamentals

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Discussion and questions related to the course EFI Tuning Fundamentals

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is it possible for injector duty cycle to go beyond 100%? Is it different for Di vs Pi vehicles as I’ve seen people read higher than 100% duty in some circumstances on di cars

G'day Alastair.

No, its not physically possible for a duty cycle to be higher than 100%. Duty cycle is the percentage of a fixed time period for which the injector is open, if its 50%, the injector is open for half of that fixed time period, if its 100%, the injectors is open for the entire time period.

Some ECU's will report duty cycles higher than 100% however, as the background fueling equation may result in the ideal pulse width being higher than 100%, but in reality this will just result in the injector being constantly 'on'.

If you see this happening, chances are very high that you need larger injectors to complete the tuning operation.

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