Need help understanding B8020 and B8021 settings

[Chalky]

Trying to get my head around the E38. Can someone explain how these tables might need to be adjusted?

Car is C6 LS7 Corvette with headers and intake, predominately for street use. Just trying to figure out how to apply these tables based on how I drive.

[Taz]

Hello Chalky,

I am "in the boat beside you" as the saying goes. I had worked hard to gain a certain level of comfort and competence with the LS1-B PCM, and am now trying to do the same with the E38 - but the learning curve is fairly steep.

I read through Swingtan's VVE Adjustment Tutorial and the EFILive Virtual VE Tutorial - at least 20 times each - making notes each time - then reorganizing these notes as I began to understand the documents.

Here is my understanding of B8020 (Operating Zone RPM Boundaries) and B8021 (Operating Zone MAP Boundaries) - which could be completely incorrect !! Swingtan is our resident expert - but I think it's about 4:00 AM currently in his area of the world.

B8020 creates 5 RPM zones, and B8021 creates 6 MAP zones. These combine to create 30 sections in the VVE table (B8101 for NA vehicles). Each section may contain a convex curve (rising) or concave curve (dip) - but not both (wave). As you begin to work on your VVE tuning - you will see how the "BEN" changes will begin to alter the shape of the VVE 3D shape. By identifying where a "wave" is or has formed, will indicate a natural break point in your particular VVE shape. As an example, altering the RPM break points (B8020) to correspond with the centre of this wave (i.e. concave on one side, convex on the other) may bring the VVE table back into compliance.

As I stated before, my understanding of VVE tuning is very rudimentary at this time - I find I am progressing in a two steps forward, one step back type fashion !


Regards,
Taz

[Chalky]

Taz:

Thanks for the reply and the information. That makes sense in adjusting after you start tweaking the VVE table. I thought people were changing the two tables based on driving styles.
Like you, all of my past experiences were with LS1-6 motors. The E38 experience is a new ballgame. :)

My stock VVE table in my LS7 looks like parts of it were chiseled with vertical and horizontal walls. Just adds to my confusion but also seems to indicate what is possible and acceptable.

[swingtan]

B8020 creates 5 RPM zones,

Correct


B8021 creates 6 MAP zones.

Correct


These combine to create 30 sections in the VVE table (B8101 for NA vehicles).

Correct


Each section may contain a convex curve (rising) or concave curve (dip) - but not both (wave).

Correct. This would also appear to hold true for both the RPM and MAP curves.


As you begin to work on your VVE tuning - you will see how the "BEN" changes will begin to alter the shape of the VVE 3D shape. By identifying where a "wave" is or has formed, will indicate a natural break point in your particular VVE shape. As an example, altering the RPM break points (B8020) to correspond with the centre of this wave (i.e. concave on one side, convex on the other) may bring the VVE table back into compliance.

Additionally, you want to try and get "normal driving condition points" in the center of a zone. For example, Idle, cruise, general acceleration, WOT, are all conditions that I try to have in the centre of a zone. This is because as you near the edge of a zone, the adjacent zone has an influence on those cells when you generate the coeffs. Also remember, a zone MUST be at at least 3x3 cells in size

Finally, a tip to see just what can happen with the VVE and making adjustments. try the following.


Open the VVE and press F2 to bring up the table.
Find a large zone and select a cell in the middle of the zone.
enter a "0" in that cell, then generate the coeffs and generate the VVE again.
Notice what happened to the cell that was set to "0" as well as it's neighboring cells.
Next, select a cell that is at a corner of the zone, where it meets 3 other zones.
Again, enter "0" and generate the coeffs. and the VVE.
Note the cell value as well as what happened to the cells in all 4 zones.


The VVE is not a direct 1:1 table like the LS1 VE table is. You need to think of the VVE as a whole for nearly every change you make, as you are never adjusting a single cell and rarely adjusting a single zone.

Simon

[Chalky]

OK, in B8020, in my case the car idles at 650, I normally shift around 3500-3000, cruise rpm is approx 1600 in 6th, redline is 7K. How would I apply these variables to B8020?