Injector Pulse Width?

[rammertide07]

Is there any relation in injector pulse width and fuel milage? Seems like the shorter the pulse width, the less fuel going into the cylinder...if I'm thinking injector pulse width is pretty much as its called.

[907DAVE]

Correct, pulse width is a measurement of how long the injector is commanded on. So, shorten the PW and less fuel gets injected.

However, on a HEUI injector, ICP plays a major roll in fuel delivery also. More ICP = more fuel...faster. If PW was to remain constant and ICP was to increase, more fuel will be injected.

Make sense?

[rammertide07]

Originally Posted by 907DAVE

Correct, pulse width is a measurement of how long the injector is commanded on. So, shorten the PW and less fuel gets injected.

However, on a HEUI injector, ICP plays a major roll in fuel delivery also. More ICP = more fuel...faster. If PW was to remain constant and ICP was to increase, more fuel will be injected.

Make sense?

Kinda, doesn't that just mean the pulses of fuel are the same....just under more pressure with more oil? Or is it squeezing in more fuel with more pressure?

[ticopowell]

I think both come into play, with ICP, more pressure equals more fuel, but the pulse width is still variable based on what the computer says.

[907DAVE]

Originally Posted by rammertide07

Kinda, doesn't that just mean the pulses of fuel are the same....just under more pressure with more oil? Or is it squeezing in more fuel with more pressure?

Sorta, more pressure driving the fuel plunger means more fuel is going to be injected in the same amount of TIME. Remember, pulse width is a measurement of the injector "on" time - regardless of how much fuel is actually being delivered.

Originally Posted by ticopowell

I think both come into play, with ICP, more pressure equals more fuel, but the pulse width is still variable based on what the computer says.

Yup, but so is ICP.

[rammertide07]

Originally Posted by 907DAVE

Sorta, more pressure driving the fuel plunger means more fuel is going to be injected in the same amount of TIME. Remember, pulse width is a measurement of the injector "on" time - regardless of how much fuel is actually being delivered.

So fuel plunger travle depends on oil pressure? I always thought it was the same travle distance each time.

[TwinTurbo]

I think i have an analogy that will hopefully clear up any confusion. Say you have a syringe full of water, and you hold your finger over the end. Now push down on the plunger with a light amount of pressure and remove you finger for 1/2 a sec. - the same amount of water will always come out if the pressure and time stay the same. Now increase the pressure on the plunger but keep the time your finger is off the end the same - more water comes out, lower the pressure but leave your finger off the end longer = more water out. Pulse width = time finger is off the end, ICP = pressure on the plunger. Hope that helps.

[907DAVE]

Excellent analogy!

[rammertide07]

Originally Posted by TwinTurbo

I think i have an analogy that will hopefully clear up any confusion. Say you have a syringe full of water, and you hold your finger over the end. Now push down on the plunger with a light amount of pressure and remove you finger for 1/2 a sec. - the same amount of water will always come out if the pressure and time stay the same. Now increase the pressure on the plunger but keep the time your finger is off the end the same - more water comes out, lower the pressure but leave your finger off the end longer = more water out. Pulse width = time finger is off the end, ICP = pressure on the plunger. Hope that helps.

What 907Dave said!!! Thanks

[TwinTurbo]

Just glad I could contribute something useful