Injector Time

[Yellow67stang]

Sorry if I am asking stupid questions

If you increase the injector opening time you are increasing fuel delivery correct? From say.....1.0ms to .8ms

Or is it opening quicker but less fuel come out everytime?

Could somebody explain to me why you would want either or?

Thanks

 

[T66Typhoon]

Injector opening time is an assumption that you give the computer to use in some of its calculations.

If you say = 1.0 you are not physically changing the "open" time... you are just telling the ECU that is takes approximately 1ms for injector to open.

Hope that helps.

Nick

 

[Craig Smith]

The injector opening time you enter in the calibration is basically to make up for the time it takes for the signal applied to the injector to actually make fuel start flowing into the intake. Whatever value you enter here gets tacked on to the injector pulsewidth that the speed/density calculation comes up with.

Increasing this value therefore richens the motor everywhere, and vice versa. The differences that this makes are more pronounced at idle and light cruise, since the pulsewidths there are small to begin with.

 

[Yellow67stang]

So, how should I set it up for a race type setup that doesnt really need to idle very well anyway.

Do you find that people use the pulsewidth to put more or less fuel in the car as a tuning method. Or just use the VE table and keep the pulse the same all the time?

 

[bobc455]

I assume you're using the FAST?

You should set the target A/F ratio to wherever you desire (13.8:1 for idle, 14.5:1 for cruising, 11.5:1 for WOT are pretty common numbers).

Then, set the VE table so that the actual A/F ratio is very close to the target A/F ratio with the least amount of correction from the O2 sensor.

Injector opening time is a charachteristic of your injectors, and isn't a really a tuning parameter. The bulk of your initial tuning will be to get the VE table accurate- you can simultaneously make tuning changes to the A/F ratio to see how it affects perforamance (the O2 correction will act as a tuning band-aid until you get your VE table just right).

-Bob Cunningham

 

[Yellow67stang]

Thanks Bob!


So, I have 2 "tuners" help me with my setup. And they each set the pulse at different rates. One is 1.0ms and the other is .8ms on the same engine. If this is a global type parameter then why the difference? To me I see it as a "tuning" method but do not know the advantage or disadvantage of playing with the number according to what you people are saying.

 

[91cam447]

If you are running the FAST in Alpha N, your don't have a AE fuel table. Your fuel table is tuned using injector pulse width. Are you running the system in Speed Density or Alpha N??

 

[Yellow67stang]

speed