Globy

Hello,

Can anyone give me a detailed explaination of what dutycycle is?
I'm tired of read things about throttle dutycycle, wastegate dutycycle, etc.... and not know what it is.

Beastie

iTrader: (2)

Duty cycle is the percentage of time the item being controlled is switched on.

Injectors at 100% duty cycle are fully open. Injectors at 50% duty cycle receive a pulse to switch them open only half the time of their full capacity.

Same for wastegate, where the boost pressure is controlled by switching the solenoid on and off rapidly to control the boost pressure. If the wastegate is at 100% duty cycle and the boost pressure still rises then you need to change the boost control solenoid to a larger bore item or change the wastegate so it can still be controlled within the operating parameters of the system.

Throttle duty cycle i think relates to fly by wire throttles which are controlled by a potentiometer that sends the system a signal and thus the ECU fuels the injectors accordingly.

This is a bit rough explanation but i am sure someone else will be along shortly.

MartynJ

Sort of !

Wastegate duty cycle refers to the amount of time the boost control solenoid is open and increasing boost. So more duty = more boost, not less.

Globy

Thanks for the ones who replied.But just to be more detailed, here it is from a book

"Duty Cycle versus Pulse Width

Often the computer controls the results of the output by controlling the duty cycle or pulse width of the actuator. Duty cycle is a measurement of the amount of time something is on compared to the time of one cycle and is measured in a percentage. When measuring duty cycle, you are looking at the amount of time something is on during one cycle. Pulse width is similar to duty cycle except that it is the exact time something is turned on and is measured in milliseconds."

Globy

So I have another question,

The signal that the ECU sends to the actuator ( wastegate, throttle body, etc..) are digital or analogue signals?
The point is, that it should have an DAC before the signal go to the actuator, but I think these does not hapen, correct?
Or the ECU does the conversion and sends an analogue pulse, switching on and off??

I'm really confused on this one!