IFR Value Limit Workaround - Parameters to scale?

[angrygoat]

But, yeah, based on what Greg said, you shouldn't have to scale your VE table since it references the Engine Displacement, therefore it's calculations should be accurate.

I'll let Greg chime in here, tho.

Does the same hold true for the E40s? Seems like everyone says the eng displacement has nothing to do with VE since its wrong from the factory.

[eficalibrator]

Anything that uses units of "GMVE" for the VE tables (including all new e38, e67, and some e40's with their "virtual VE" equation-based systems) had displacement baked into the value. These are easily recognized since they're no 0-100 type numbers, but rather in the several thousand range due to the change in units. Regardless, since volume is baked into the surface, the entire surface would be scaled down by the appropriate value in order to keep the dyn_air model properly matched to your scaled fuel flow.

As for scaling the spark tables, I typically work offline and start with the lowest g/cyl rows and work up from there to avoid pasting over something I'll need a few calculations later. The complete scaling exercise is part of my Advanced GM classes, since there's more to it than just MAF, VE, and IFR if you really want to do it right.

[DSteck]

What are some common ratios to scale by? I was going to build an Excel spread sheet that would allow one to paste a spark table, select a tab related to the scaling % they want, and it would spit out a scaled table. I was thinking 80%, 75%, and 50%... Any others that would be useful?



It's slow at work. Leave me alone!

[JoeCiv]

What are some common ratios to scale by? I was going to build an Excel spread sheet that would allow one to paste a spark table, select a tab related to the scaling % they want, and it would spit out a scaled table. I was thinking 80%, 75%, and 50%... Any others that would be useful?

i actually made that in excel. paste in your spark tables, and the amount you want to scale by. It quadruples the amount of rows and interpolates so you are getting spark numbers matching your airflow row with more accuracy. then it spits out your new table.. had to make different sheets for the knock sensor tables as they use different breakpoints. i was going to post it up, but it still needs a little work to make it user friendly...

[DSteck]

Ok, for main spark scaling, give this a shot:

http://pages.slu.edu/student/steckdw...%20Scaling.xls

I based this off of the main spark table from a stock C6 Z06 calibration. I'm sure the axes probably don't line up with every tune out there, and there's only three scaling options right now. It will automatically round to the nearest half degree, as well.

Let me know what other scaling ratios people would like to see. I'll add a knock sensor one another time so that all the data gets pasted onto the first sheet, and then you just choose the appropriate sheet for the scaling ratio you need to use.

EDIT: Updated to add knock sensor table stuff.

[JoeCiv]

just noticed something in my tune under idle airflow

ECT area scaler and effective area

i really dont know exactly what this is, but im thinking that because all the airflow values were cut in half (in my tune), and the engine thinks it is flowing half of what it really is.... that this would need to be scaled as well? doubled?

[RWTD]

ETC Area Scalar is just an equation to convert the effective area of the TB. No need to scale it, bud. If you ever go with a larger TB, that's a different story.

[JoeCiv]

ETC Area Scalar is just an equation to convert the effective area of the TB. No need to scale it, bud. If you ever go with a larger TB, that's a different story.

Well if scaling is basically makes the computer think the engine is half as big as it really is, would the TB need to flow half as much??

im just trying to figure out what may be causing a P0121 - TP sensor circuit insufficient activity. first time ive seen it and all I did was scale the tune to 50% vs. the 80% i originally did.

Also, as far as scaling, how about the reversion tables "Ve Lo Altd" and "VE High Altd"

And under OL & CL - mode vs. airflow?

[RWTD]

No, again, you don't scale the effective area stuff for the TB. It tells the pcm the effective size of the TB for operational control, not airflow flowing through.

The reason you're getting a P0121 is because now since you scaled the Diagnostic Tests are seeing 1/2 of what they were, and that is too far out of range. You'll just have to disable the P0101, P0106, and P0121 test, as it doesn't look like HPT has the actual tables yet to modify for those.

As for the "Ve Lo Altd" and "VE High Altd", what vehicle are you tuning? Those tables are generally not used, and are zeroed out on the Vettes and G8 and GXP.


In regards to the "Mode vs. Airflow", yes, the axis values are actually in lb/hr, hence airflow, and since the axis is not able to be renormalized, you'd need to shift the cells to correspond with your ratio.

Take an '08 Z06 for example:

Labels	0	32	63	95	127	159	190	222	254	286	317	349	381	413	444	476	508	540	571	603	635	667	698	730	762	794	825	857	889	921	952	984	1016
Normal	0	8	8	14	21.4	24.6	27.4	30	33	36	40	44	47	50	52.4	54.4	55.8	56.6	57.4	58.1	58.7	59.3	60	60.5	61	61.4	62	62.4	62.7	63	63.3	63.5	63.8
DOD	0	8	8	14	21.4	24.6	27.4	30	33	36	40	44	47	50	52.4	54.4	55.8	56.6	57.4	58.1	58.7	59.3	60	60.5	61	61.4	62	62.4	62.7	63	63.3	63.5	63.8

At a 50% scale, here's what it should be changed to:

Labels	0	32	63	95	127	159	190	222	254	286	317	349	381	413	444	476	508	540	571	603	635	667	698	730	762	794	825	857	889	921	952	984	1016
Normal	0	8	21.4	27.4	33	40	47	52.4	55.8	57.4	58.7	60	61	62	62.7	63.3	63.8	63.8	63.8	63.8	63.8	63.8	63.8	63.8	63.8	63.8	63.8	63.8	63.8	63.8	63.8	63.8	63.8
DOD	0	8	21.4	27.4	33	40	47	52.4	55.8	57.4	58.7	60	61	62	62.7	63.3	63.8	63.8	63.8	63.8	63.8	63.8	63.8	63.8	63.8	63.8	63.8	63.8	63.8	63.8	63.8	63.8	63.8

[JoeCiv]

for the ve high./low its an 05 GTO... they are populated and one strange thing is that they are supposably min values, but some are larger than the values in the main ve table.... maybe it just isnt used?

picture below is from the stock gto tune....




I just turned off those tests, and realized I should have from the beginning as I had them disabled in my 80% tune...

mode vs. airflow, had that done, just wanted to make sure....

[carlrx7]

Anyway, thanks to some quick work with Excel, I was able to easily interpolate and match all the values to the proper load points. As mentioned, there's a LOT of stuff that's referenced, such as idle parameters, spark, knock sensors, etc., so it did take a bit of time and work to make sure all the tables and their values were set correctly before I flashed the vehicle.

Regards,

James

Can you describe the process of the excel work at hand? i have a way of doing it, but its taking me like 45 mins on just the 'Cylinder Charge Temperature Bias vs. Airflow' table, going from 4g/sec to 3.2g/sec sucks.

i would interpolate from 0-4, then again between 3.0-4.0 to get the 3.2 value,, is this what you do, or is there a quicker way.?

[DSteck]

The Cylinder Charge Temperature Bias vs. Airflow is linear, so that should be easy for you to scale. The value at zero doesn't change, but let's say you scaled by 75%. The value at 96 g/sec comes from the value that's originally at 128 g/sec. With those two data points, you can make an equation to figure out every other value. Using a stock C6 Z06 table...

0 = 0.26289
128 = 0.05646

New table:
0 = 0.26289
96 = 0.05646

Equation: Bias = -0.0022*(airflow) + 0.26289

[carlrx7]

alright, i get it, but you guys make it seem so simple :thumbs: . now if i could only get excel to do the numbers for me.

also, is there an easy way to determine if the table is liner?

[DSteck]

Graph it, add a trendline, make the trendline linear, and have it show the R² value. If R² is 1, it's dead nuts linear. You can typically tell by looking at the graph and making an educated guess.

[carlrx7]

maybe its time for me to invest in the video professor.

[angrygoat]

+1

[JoeCiv]

The Cylinder Charge Temperature Bias vs. Airflow is linear, so that should be easy for you to scale.

mine wasnt linear until about 48 g/s on the stock tune.... (05 gto, e40)

see attached.

[carlrx7]

i just went into 2d graph mode and can see that its a straight line. so that helps alot early!

[carlrx7]

ok. the linear tables where easy. but now im working on the :
Fuel Control
Open & Closed Loop
General
Closed Loop Mode vs. Airflow

tables not linear. i got most of the columns transferred . ex. 128 to the 96 column. and so on. but i still got a lot of column's that dont have any values.

what i thought would work as, add columns inbewteen, like from 0-4, 0,1,2,3,4. then avg the 0 colum and 4 to get 2, then avg 0and 2 to get 1, and the same for the 2-4, to get 3. then put the 3 value into the 4 column for being scaled 75%

any easier way of doing this?

ok, i found another thing.

i cut the ifrvs kpa down to 75%, if i goto Flowrate modifier VS. Voltage and put in 1.25, ill it all good now? if i dont hit 512g/sec then i dont need to scale right?

[RWTD]

Carl, see my post #49 above for the "Mode vs. Airflow". That's the easiest if you're using 50%. However, you'll have to interpolate beween the axis labels for any other value.