NefMoto

Ultra noob question here.

1.8t AWP me7.5

Have 3 bar FPR, changing to 4 bar

If injector on time = ('roughly') Load*KRKTE*req_lambda

I would lower KRKTE correct? it's currently something like .11564...some numbers, I don't remember. .11 is correct though, ms/%
How much would I lower it by? What do you gauge this scale by? (difference of amount to dial back for 4 bar as opposed to 5 bar) I assume when logging, I would change this and check injector on time and IDC. Anything else?

When upgrading FPR, does anything else need to be changed other than KRKTE?

sorry if this is a repetitive question that every noob asks.... :'(

krkte & kvb
iirc 0.0854 & 341

krkte * 3/4

Did you bother reading the s4wiki page?

http://s4wiki.com/wiki/Fuel_injectors

And the tuning page

http://s4wiki.com/wiki/Tuning#Primary

which links here
http://nefariousmotorsports.com/forum/index.php/topic,320.msg6774.html#msg6774

which says:
KRKTE = 50.2624*(Liters/Cylinder)/(operating flow rate in cc/min * .684 constant )

Whoa, alright, I didn't know about the first and last pages, I didn't know they existed. my bad.

2nd link: I did know about that one but I wasn't sure if it applied from a 2.7t to a 1.8t and I also didn't really understand how to convert ms/% to cc/min. wasn't sure if it was cc/min/%.....
The info kinda tripped me up.

Yea i dunno, I guess my ability to find this information is pretty sub par. I'm tryin' here. I'll read all that info. my bad dudes.

If you are good at dimensional analysis you can do this from first principles.

ms->min is easy.

1 minute = 60 * 1000 milliseconds.

100% = 100% load  = how much fuel to go with one cylinder full of air at STP.. so figure out how much air mass is in a full cyl of air at STP, then divide by 14.7 etc... in grams. Then convert that to cc (density of gasoline).

I would go through the whole calc but if you are bored you can try for it.

converting cc/min to different values based on spec pressure vs actual fuel pressure is covered in the injector page.

Did the calculations and am posting here mainly to show ya'll that I'm not dumb  :P

found info on my injectors and needed to scale the flow up for 4 bar FPR. I'm sure others have posted this before but whatever. If anyone else has these injectors:

2002-2004 AWP 180 317cc 3bar 06A 906 031 BA 0 280 156 061 EV6

using equation from s4wiki:

365.925=(√(58.0/43.5))*316.9

316.9cc @ 3 bar
365.9cc @ 4 bar

50.2624*0.4452/ (317*.684)=
50.2624*0.4452/ 216.828=
22.3768205/ 216.828=
.10320079 - old KRKTE (.10301 in bin)

50.2624*0.4452/ (365.9*.684)=
50.2624*0.4452/ 250.2756=
22.37682048/ 250.2756=
.0894087177 - new KRKTE

someone confirm my math?

Also, not sure if anyone has this document for ev12 and 6 injectors but info for EV12s and 6s are not on the wiki (not sure if they pertain to s4's) attached.

lots of people over-complicate this.  Here's my approach.

1) find your increase in flow due to new injectors or FPR

1 - (316.9 / 365.9) = .134 flow increase

2) subtract from current constant based on flow increase

.10329978 - (.10329978 * .134) = .089458

That should get you darn close.  Go for a drive and note the partial load LTFT afterward.  Increase or decrease KRKTE based on LTFT.  Rinse and repeat in needed.

x - (x * (1 - k)) = x*k

You can just .10329978 * (316.9/365.9) dude.

hooray math  ;D

how sensitive is this?
to the
.00000 degree?
.0000 degree?
.000 degree?
.00 degree?
.0 degree?

meaning, at what placement should I begin my adjustments if needed?

thousandths

Generally, 3 or 4 sig figs.

So
XXXX
XXX.X
XX.XX
X.XXX
0.XXXX
0.0XXXX
0.00XXXX

https://en.wikipedia.org/wiki/Significant_figures

at 0.0XX that is only 2 sigfigs... not good enough, IMO.