RedHardSupra

iTrader: (1)

How do I convert injector pulse width to duty cycle?
I have the lookup tables, but I'd like it calculatable so I can graph some things against each other.
thanks

HumpinSS

iTrader: (1)

Ill tell you when i get home if no one has posted it


injpw*rpm/1200

RedHardSupra

iTrader: (1)

so based on the equation posted by humipinss, i made two graphs for two different situations:

RPM vs Pulse Width


and

RPM vs Duty Cycle


hope that comes in useful for someone,
Marcin

WS6FirebirdTA00

iTrader: (33)

awesome man, makes it a lot easier on us all, and well isnt that what we are all looking for anyway

soundengineer

iTrader: (16)

can anybody post a spreadsheet that I can plug #'s into???
and what #'s do I use to get the injector pulses for my entire engine plot like that...

I could probably make a spredsheet myself if I knew where to get a full table of my injector pulses........

I have HPTuners by the way

horist

Added to main sticky

soundengineer

iTrader: (16)

yes... but you didnt answer any of my questions..all you did was add this post toa sticky...doesnt tell me anything about where to get the info I need so I can plug it into the equation.....

horist

That post wasn't directed towards you and wasn't meant to answer any of your questions... it was to inform everyone that it's been added...

As for where to get the info... your scanner... log injector pulse width and then use the formulas that are listed... IPW will be in seconds, you just need to log RPM, and IPW ... 1200 is a constant


http://www.transamws6.net/HPTuners/injpwcalc.xls is the same thing that's been posted for download


RedHardSupra: hope you don't mind me duplicating it... I added credit to you in the beginning of the file (was kinda fun setting it up.. I've never used absolute $ cell references and conditional shading before)

RedHardSupra

iTrader: (1)

hey Horist, thanks for a sticky!

and no, of course i don't mind, and thanks for giving credit where credit's due.
if you want more excel tricks, look at the MAF calibration spreadsheet, that has some rather advanced concepts like array formulas.
where in IL are you? I don't know anyone local that tunes stuff, i'd love to buy you a beer and pick your brain.
PM me if you're intersted.
Marcin

RedHardSupra

iTrader: (1)

actually, what is that 1200 constant do? where does it come from?

horist

I'm up a bit north of you near Wauconda/Lake Zurich area

as for the 1200 constant... did a quick search and Paul@EfiLive explained in the past

TXNC5

I am sure Paul is correct, but I have a question about pulse time. Is the injector spraying while the intake valve is closed?

6000 RPM = 100 revolutions per second

1 revolution = .01 seconds (or 10ms)
2 revolutions = .02 seconds (complete 4 stroke)

How long is the intake valve open? If the injector is spraying for 15ms, doesn't it have to be spraying while the valve is closed?

WS6FirebirdTA00

iTrader: (33)

i was trying to figure out pulse width fuel vs air % to try and see where i stand for tuning my injectors, if anyone has some idea on this iwould like to know, i tried earlier but never finished

RedHardSupra

iTrader: (1)

some more poking at injector duty cycle, but this time it's used for getting your volumetric efficiency too

http://redhardsupra.blogspot.com/200...olumetric.html

b727pic

iTrader: (1)

Thanks for the help.....looks alot better than what I had last night.

EFI-101

Here's another method:

Inj PW/ [{1/RPM}*120]=Inj Duty %

Great graphs by the way guys....

There are lots of ways to get there....just depends which road you like! LOL

soundengineer

iTrader: (16)

wouldnt it be easier to say
Inj PW / (120/RPM) = Duty
or
Inj PW x RPM / 12 = Duty

remember injector pulse width in th eformula here is in seconds....
so 2.5 miliseconds = .025

LS1 Sounds

iTrader: (11)

I think you made a typo, 2.5 ms would be 0.0025 sec. Thanks for the info and sheets guys.