Max INJECTOR DUTY CYCLE

[lambda1]

Hi,
I have 2015 Charger Scat Pack. During WOT it goes lean (actually it goes not rich enough) and on the dyno I can see that once it reaches 5700rpm the power is not increasing anymore:
dyno scat pack .png

Lambda commanded is 0.84 and at WOT car is unable to reach commanded AFR.

I checked the fuel pressure - not dropping, stable 60 psi during the pull.

During a pull I can see that injector pulse width reaches 80% at 5700RPM and that is its max. On higher RPMs it is not commanding more fuel, because it is already at 80%. Puls width is 17ms.

wot run.png

Question is : is it the maximum for these injectors? I know people say 80% is max healthy duty cycle, but is it possible that stock injectors are at its maximum in this carwith those mods? Car has long tube headers and removed all mufflers, JTL cold air intake.

Also is there a table in the tune that blocks the duty cycle to 80% ?
tune and log attached.

scat pack tune.hpt
2024.08.30 - INJ Duty.hpl

[edcmat-l1]

In my experience, if you keep the neural network on, it will "clip" your PE. Put it in speed density and dial it in it works just fine.

That being said I have not used the neural network trainer enough to find out if that is a fix.

Only other way I've been able to get the desired AFR while still in NN is skewing the injector flow rate tables and I'm not a fan of that at all.

[lambda1]

would it help if I increased fuel pressure ?

[LilSick]

would it help if I increased fuel pressure ?

you are not logging knock voltage and your are not paying attention to the knock retard

the tune is way off - look at the purple line dead center in your log on my layout

that is knock retard

you need to fix that before you worry about more fuel

[LilSick]

also, how many ms of an injection stroke are there at 6000 rpm?

my math says 20

20 ms

even if you are still injecting fuel, what good is that gonna do once the valve is closed?


6000 rpm

rev per min

100 rev per second

100 times the piston goes down from tdc to bdc; and 100 times it goes back up to tdc again (200 strokes)

but only 1/4 of those strokes (50) are intake strokes

50 intake strokes per second at 6000 rpm

1000 mili's in a second

1000/50=20

dont trip on DC... there are only 20 ms avail to inject fuel (at 6000 rpm)

unless you can bend time you cannot inject fuel for longer than 20 ms at 6k

[lambda1]

you are not logging knock voltage and your are not paying attention to the knock retard

the tune is way off - look at the purple line dead center in your log on my layout

that is knock retard

you need to fix that before you worry about more fuel

thanks. The car was tuned by someone else before and I did not get to spark yet, just stuck in the VE wondering why it goes lean.

[LilSick]

it might not even be spark (causing the crazy retard)

it prolly isn't

its prolly something else like airflow or cam error or

my point is that i would get that sorted first

good luck

[10le]

Hi

In our BMW world we are running DC of 85% -90%.
So there is enough reserve you can use.

For Long-terms you really shouldn't go beyond 90%. If you have a bad gut feeling and your decisions tend to be more conservativ, stay at 85%.


Servus
10le

[lambda1]

I tuned the spark and it seems ok now.

If i decided to go over 80%, what shod I change i the tune?
Whkch parameters /tabmes in the tune are blocking the i injectors at 80%?

[Hellscat2018]

you have a mech issue, nothing you do with that stock setup is gonna run out of fuel, return tune to stock tune and start looking for problems, datalog and see if your getting throttle cut, and see if the pedal stays in control of the throttle on the whole pull