Scaling Percentage A9L2

[Jstauffe]

Ok I keep getting confused by this value and the automatic scaling that happens. There used to be a writeup for this in the old forum, but I can't seem to find it now. The comments in Tuner Pro are a also bit confusing to me.

I think I'm chasing my tail here, trying to get my high slope right I feel like its all moving together.

Can you give me an explanation of exactly how this works, and maybe an example?

Say, as an example, I take the stock A9L2 file, and want to put in 24 lb injectors, and a 24lb mass air. What are the exact steps to...

1. Initially set up the file
2. Tune the file. (logistically how to change these values in the software to avoid the auto scaling)
a. Scaling Percentage
b. Low Slope
c. High slope
d. Breakpoint
e. if necessary mass air xfr

The strides that have been made with the A9L code on this website are quite impressive. I've got a '66 coupe with a 289 and an A9L. Been this way since '98. I just added AC and an electric fan, and other than this scaling thing my thick brain can't figure out, the car almost tunes itself!

Thanks in advance for your help!
Jonathan

[decipha]

http://www.efidynotuning.com/a9l2.htm

its all in there

[Jstauffe]

Thanks for the quick reply and link. It is informative, but doesn't really give an explanation of how it is intended to work. My issue is I 'feel' like I've set it up, I start with a solid tune, add the mass air curve and stock injector settings, CID, etc, and when I go to tune, especially the high slope, the CID and mass air meter curve change of their own accord. I think this is happening automatically with this scaling. The notes in TunerPro lead me down this path, and the fact that you mention in the above link to do things 'in this order', and changing injector data requires 'updating all SP** params.'

When I'm tuning I start with the low slope, to get my idle solid, and then move on to the high slope, but haven't been watching the other SP params. This must be what's tripping me up. Is there a way to just turn off this automatic scaling? How is it supposed to work?

Let me ask the question this way, as I am seeking to understand the logic. What if I want to use this scaling function as it was meant to be used? What is its intended purpose? How would I use it?

Thanks again for your patience and help.

[Jstauffe]

Ok I've been playing with this some more, and this might be obvious to most on this forum, but it did trip me up. Every time you change the high slope, as the instructions say, you need to check the other SP** functions. The one thing that caught me is that, I have all the little windows pulled up for all the SP** functions, and they do not all update live in tunerpro when the high slope changes. The only one I saw change live is the scaling factor. You have to close the little windows and open them back up again to see the change.

How does this auto calc work with the emulate functionality? Does tunerpro update all of the SP** params when changing the high slope in emulate?

[decipha]

Ah I see your confusion now.

The K-Constant is a global fuel modifier. It is the single most important value in the ecu and is the twin sibling to the injector high slope. The K-Constant should always be set to 30 lbs/hr as that gives the maximum resolution in the ecu for any tune. Why 30? On eec-v the injector slopes have a maximum value clip based on processor speed and 30 ensures you dont butt up against any of those clips including when deltap modifiers come in to affect. Also 30 lbs/hr of fuel pegs the injector duty cycle just under the airmass clip of 64 lbs/min (~1750 kg/hr) which is the maximum airmass clip on eec-v, some powerpc and even some other oddball 4 cylinder and 6 cyl applications. And to even furthur that on returnless fuel systems 30 moves the maximum fuel pump flow rate just past 4 (the maximum the ecu can calculate) so there is no longer a fuel pump flow rate limit when dialing in the fuel pump voltage. So in summary a k-constant value of 30 is the absolute perfect value for the ecu to no longer have any fueling, airmass or fuel flow limitations with the absolute maximum resolution possible. Its also a nice and easy to remember whole round number. The objective here is easy.

As a side bonus you can very easily see exactly where the injectors and maf peg out now without having to calculate it simply by looking at the maximum airmass possible in any of the SP** airmass functions. Simply divide your maximum airmass your reaching at wot by that and you know how exactly much headroom you have just that simple. It might not sound like much but it makes life significantly easier when turning up the boost later down the line not having to question if your going to peg something. One more reason the K-Constant needs to be set to 30 is that the rwhp and rwtq values calculated in my adx are based on that. Even though they are not accurate they rely on that value for a baseline as everything my adx self calculates in tunerpro is based on the K-Constant not changing.

So as you can infer changing the K-Constant will change the entire foundation of the tune. If your K-Constant on an existing tune is anything other than 30 then you will need to verify you did not clip the injector maximum slope value with the deltap modifiers taken in to account. If you hadn't then the easiest way to do that on an already dialed in existing tune is to just change the WARNING!!! INJECTOR HIGH SLOPE scalar to your existing injectors UNSCALED ACTUAL INJECTOR HIGH SLOPE value from the manufacturers published data sheet and save that tune. Now if you go look at any of the SP** values in your tune its going to show you what your actual unscaled values that are currently in your existing tune. If any of those values are incorrect then your tuner did not scale your tune properly. Your K-Constant wont be at 30 as it should be at this point but thats fine for now.

If your slope did exceed the maximum slope clip then you need to re-dial in the tune from the top down. More on that if someone requests it as it can get tedious to explain.

Now open up the compare with the same newy saved file comparing against itself and it will show 0 changes.

Go through the steps in the exact order outlined on the A9L2 write up MANUALLY selecting all and copying and pasting the values from the existing saved tunes compare as you go through the steps. You will now end up with a properly configured tune.

On all fords changing the high slope changes the entire tune. Its the same as its always been just more prevalent now.

[Jstauffe]

Thanks for the explanation! I figured there was an in depth reason for your logic. Now I understand a little bit better.

I never changed the K-Constant, so I'm good there. I just need to start over with this knowledge in mind. Establish a baseline tune, save it, create a new tune from that baseline, and when I change the high slope, use the compare function to check against the baseline tune. I was definitely chasing my tail yesterday.

One final question. If I change the high slope in emulate mode, does it automatically change the other values at the same time in emulate mode, or is it more of a tunerpro only change that you don't catch until the next time you download? I think this may have been tripping me up as well.

Thanks again!

[decipha]

Specifically when your dialing in fuel while tuning if you change the high slope it doesnt actually adjust fueling any; it only changes the scaling percentage so all the SP** values display differently. It makes no difference if your emulating or not as the logged values on the tunerpro dash as well as all the SP** values will all change as soon as you write that new updated value. If any of the SP** parameters are already opened though as youve observed the value will not be correct til you close it out and open that parameter again.

if your dialing in the injectors then it makes life even easier as you dont have to worry about the high slope at all. You simply dial in the maf, the low slope, breakpoint and offset just as you would otherwise applying any would-be high slope correction to the entire maf curve and engine size (SARCHG).

Once youve got it dialed in you simply adjust the high slope to a more accurate value that youve determined to be correct and you will see all your actual values. If your tune was all setup properly then once you do youll see SARCHG is now your actual engine size.


However if you had no data to start with for the maf nor the injectors and have absolutely no idea what your actual high slope value should be then after youve got fuel dialed in you can dial in SARCHG to get your LOAD values at WOT where they should be for your setup. Then you simply divide your SARCHG value by your actual engine size and apply that correction to your current high slope and you will have all actual data now solving for both unknown maf and unknown injectors.