speed density tuning 2020 GT500 ?

[spoolin342]

when using the speed density calculator how would one figure out what EXH.Map to select when making changes is there a pid or a inferred table to base it off of ? I see the max exhaust Backpressure tables but my assumption is those are limiters. any incites on this ? I'm trying to make fueling changes to get the fuel trims tighter

[b00sty]

log your LT & ST trims that will give you an idea where to make the adjustment, the same with the battery ofset get them close before using the map tables.

[spoolin342]

maybe you're misunderstanding me when using the speed density calculator you can choose the mapped point table you what to a just then there is a exhmap you can also choose which changes the tables data i what to know how do i figure out what exhmap to chose to modify?

[veeefour]

when using the speed density calculator how would one figure out what EXH.Map to select when making changes is there a pid or a inferred table to base it off of ? I see the max exhaust Backpressure tables but my assumption is those are limiters. any incites on this ? I'm trying to make fueling changes to get the fuel trims tighter

This is expected MAP(not sure exactly what this means but read it as boost), set it where you want your model to be extrapolated to.

Stock its 1.01 for n/a engine as your model should only cover that

[murfie]

An equation of a curve is identified from the MAP and cylinder air charge data points via a least-squares or other type of regression. The curve may also be scaled via a ratio of exhaust pressure versus nominal exhaust pressure.
The equation of the curve may be stored in controller memory such that cylinder air charge or MAP may be determined when the equation of the curve is indexed or multiplied by a present value of MAP or cylinder air charge.

Curve 204 represents a conventional non-blow-through (e.g., conditions where blow-through is not present) volumetric regression curve in which both x and y axes have been scaled by ExhMAP/ExhMAP_nom.
Where ExhMAP is exhaust manifold absolute pressure and where ExhMAP_nom is a nominal exhaust manifold absolute pressure (e.g. at sea level).
Instead of the cycle average exhaust manifold absolute pressure, an average over the valve-overlap window, or some other related quantity, could be used for scaling.
In engines having variable cam timing, curve 204 may be regressed from data points such as 220 into a quadratic curve.

You can find this info on the ecoboost forum in the SD sticky.

Exh. MAP.png

I believe you are talking about the exhaust manifold absolute pressure value in the Speed density calculator. I don't think you have to change this unless you are needing the SD MAP to airmass line scaled to be able to fit some exhaust gas reversion at specific cam angles and low-mid RPM. You would probably only know if you needed this if you were doing the actual regression of the line to determine the coefficents from (airmass, MAP) points.

Air mass from MAP sensor.png

Here is the math behind how it determines cylinder airmass, and hence how much fuel to inject, from the MAP sensor readings. (1-Rpb) is a push back ratio characterizing a portion of a cylinder mixture that may be pushed into the engine intake manifold from the cylinder as the piston moves in a direction toward the cylinder head while the intake valve is open. C norm accounts for physical properties of air (baro, ambient), intake manifold temperature, and cylinder displacement. I think the rest is understandable, dilution being commonly reffered to as exhaust gas reversion.

It can be an extremely sophisticated airflow model of the cyclinder, but you primarily just need to focus on MAP (sensor) to trapped cylinder air, which is the air offset, air slope, and air quad part of this image. You have wide band O2's to correct error, but probably don't have the sensors required to determine the rest of the model,and I don't think HPT calculator is setup to correct much else. You may need to just induce some error into the inferred manifold pressure, to get air-fuel ratio error reduced, if you can't determine where the error in the model is coming from exactly.

[veeefour]

This might be the case, exhaust manifold pressure aka back pressure aka boost as you would never hit anything above 1.01.
This changes with turbo. I find this necessary to change even if you deal with ecoboost just with upgraded turbo.
If you don't you end up being way too far with your adjustments.

Would you ever experience any back pressure with PD blower? Id say similar to N/A so this can be ignored completely.
You would need an actual back pressure sensor to even tell and this is how the best turbo setups are made.

In his case best to adjust the "slope" only as the model should not be that far off. Using trims, applying opposite to the tables.

[murfie]

Steady state is best. I know the thought of having to lock cams into 5-8 different mapped points just to tune fuel sounds like a PIA, but to get it accurate as the cams move around, it needs to be correct in those steady states first.

Exh MAP is mainly the late exhaust cam angles, MPs 4,5,6,7,8,10 on the 2020 GT500s where the exhaust pressure will need to be lowered so the scale of load is corrected for the exhaust gas reversion. Any other time I would leave it around baro aka 29.91. Raising it is just telling it you are still getting significant reversion and not blow through with a boosted engine. Its pure guessing unless you are regressing data points. Keep in mind you are suppose to be fitting a curve not spot correcting, but this is MP5 load with a lowered Ex MAP vs load leaving it high. I highlighted the region where things change, and its the same region you get exhaust reversion at low RPM, low-mid load. What HPT calculator is capable of showing us, is limited compared to regressing and fitting a line to the many many data points you could collect for a trapped cylinder airmass to MAP relationship.

Lo v Hi ExhMAP.jpg

[veeefour]

It goes more "flat" the higher you set it. We did few runs with back pr. sensor in 5.2/5.5 N/A builds just to see what back pressure you ever get.
We hardly ever noticed any difference in back pressure while playing with cams (EVC locked in 5.5). Free flowing exhaust vs dumps

Now when you mention this is baro referenced this gets funny even more. +2018 has baro frame sent over CAN
If you swap 3 gen into 2 gen you get baro sensor error. You wont find any baro sensor connected to 3 gen PCM.
My guess is its somewhere in A/C or inferred by any other module who knows, but its there.
Now EVERY calibration has default baro set somewhere else staring at 27 inHg ending at 31 inHg...then there is baro learning...
Id say set it to one number close to 1 atmospheric (unless you live at 3000m elevation) for SD tunig as this can make you hunting ghosts.

Calculator is there but its confusing. 99 out of 100 wont ever find it usable as it will throw funny number like 5 and plp get confued.

2020 GT500 has MAX MAP over BP divided to 26 MPs vs other cals having only one table. Keep that in mind while playing with SD.

[32vape]

Slight hijack. When trying to use the sd calculator, the changes don't stick when hitting calculate. Trying to add fuel from 6000 rpm and 40 inhg up and the figures just go back to stock when hitting calculate.

[murfie]

Slight hijack. When trying to use the sd calculator, the changes don't stick when hitting calculate. Trying to add fuel from 6000 rpm and 40 inhg up and the figures just go back to stock when hitting calculate.

The coefficients HPT calculator can come up with already fit the "curve" you are entering in the calculator well enough.

Try changing the coefficients (offset, slope, quad) and seeing what the calculator shows as loads. Trail and error if you aren't familiar with how to regress coefficients from plotted data points.

[veeefour]

Slight hijack. When trying to use the sd calculator, the changes don't stick when hitting calculate. Trying to add fuel from 6000 rpm and 40 inhg up and the figures just go back to stock when hitting calculate.

Log trims, apply opposite values to SLOPE only. This is the fastest way.