Stoich AFR numbers

[EddieD]

I have a speed density flex fuel tune on my YSi Boosted 416 stroker Camaro
Boost ref. return style Fore triple pump
ID1700 injectors
4 nozzle (2000cc total) Meth injection
18lbs max boost

My question is for knowledge as I do not have a problem with the car...

In my stoich AFR table I have odd values compared to what I see for others who just have the basic stoich values in this table.

Can anyone help me understand why my tuners values are what they are and why?
Im trying to teach myself Lamda based tuning but not sure whats happening with this table

[EddieD]

Not sure how to post the tune any help would be appreciated

[lukearmstrong1990]

stoich is best referenced to lambda.

1 lambda is stoich. 0.8 lambda is 80% of stoich and generally a ball park area for boosted tuning. 0.88 lambda is 88% of stoich and a ball park area for N/A tuning.

stoich is difference for different fuels. lambda never changes.

petrol is 14.7 stoich
E86 is 9.8 stoich.


1 lambda for petrol is 14.7:1AFR. 0.8 lambda for petrol is 12.0:1AFR
1 lambda for E85 is 9.8:1 AFR. 0.8 lambda for E85 is 7.8:1 AFR.

all oxygen sensors work in lambda. sometimes they're referred too as lambda sensors. so on a dyno a car on E85 may well show and AFR graph with 12:1 AFR. this means its showing 0.8 lambda but the dyno hasn't been told the correct stoich value for the fuel. doesn't change the tune or make the AFR wrong as its still 0.8 lambda regardless of the AFR "number"

lambda is god. AFR is simply a calculation. the stoich value for a specific fuel multiplied by the lambda value. tuning in lambda will mean you never get confused or misguided.

some tuners will fudge the stoich number in a calibration to allow bigger injectors (typically in gen 4 PCM) or to globally alter fuel in a "hack" or fudging way. make stoich lower adds fuel make stoich bigger removes fuel.

[lukearmstrong1990]

"go advanced reply"

attach file in the options bar at top of text box. browse and upload

[EddieD]

I dont have an options bar above my text box.... Is this a google chrome issue or maybe because I'm new to the forum?
When I look at comparison files i see 14.7 @0% down to 8.x @100% ethanol but my map has the below values...

AFR STOICH Table
0% = 27.7421875
6.25% = 27.06933594
12.5% = 26.39550781
18.75% = 25.72265625
25% = 25.04833984
31.25% = 24.375
37.5% = 23.70263672
43.75% = 23.02783203
50% = 22.35498047
56.25% = 21.68261719
62.5% = 21.0078125
68.75% = 20.33398438
75% = 19.66113281
81.25% = 18.98876953
87.5% = 18.31396484
93.75% = 17.64111328
100% = 16.96875

[EddieD]

Wideband says Lambda 1 at idle and is below .8 when beyond part throttle
STFT is under 9% and car runs fine

Could this be related to ID1700 injectors or speed density tune?
Its like they are double the stoich value for the what ever the alcohol content is...

HELP!?!?!

[5FDP]

What year camaro is this?

Your stoich values make sense if this is a GEN 4 camaro from 2010+. Your injector table maxes out at 127lb/hr in those years so to get around that when you have huge injectors you must double the stoich values, half the injector flow rate and half the IVT terms to trick the computer in a way.

If you click on your injector flow rate table and the values present are half what the size of your injectors really are, then that is why.

In the quick reply box below the last post in each there in the bottom right hand corner is a post quick reply, go advanced or cancel button. Click the go advanced and you can upload the file once you get there with the attachment feature. If you can't figure that out, use a different browser or google how this style forum is setup.

[lukearmstrong1990]

go to reply text box at bottom of thread, there is "post quick reply" "go advanced" "cancel"

click go advanced.

the bit above where you type with bold, italics, font selection etc has in the top row a picture of a paper clip with a down arrow. click that and then use the box that brings up to upload your tune

[EddieD]

What year camaro is this?

Your stoich values make sense if this is a GEN 4 camaro from 2010+. Your injector table maxes out at 127lb/hr in those years so to get around that when you have huge injectors you must double the stoich values, half the injector flow rate and half the IVT terms to trick the computer in a way.

If you click on your injector flow rate table and the values present are half what the size of your injectors really are, then that is why.

In the quick reply box below the last post in each there in the bottom right hand corner is a post quick reply, go advanced or cancel button. Click the go advanced and you can upload the file once you get there with the attachment feature. If you can't figure that out, use a different browser or google how this style forum is setup.

THANKS 5FDP!
Thats the answer I thought I was looking for but its not obvious... My camaro is a 2010 (E38 ECM)

My browser must not like the text entry because I don't have font or attachment options in the advanced post.
Thats a must fix LOL