This drive me crazy..
I have a long datalog with Datamaster.
I organized my excel file using filters:
Example:
Map between 48 and 52 Kpa
RPM between 1375 and 1425
Speed GT 15 mph
TpS% GT 3%
AFR EQ 14,7 (I’m monitoring closed loop no PE)
I have over 30 records with this limited values.
When I see the column FUEL trim cell I have 3 different cells involved (6, 4 and 10)
Now BLM value on cell 6 is around 118 with some 116
BLM value on cell 10 averages at about 120
BLM value on cell 4 averages at about 126
Now try to figure how to modify a VE value in this RPM/MAP range..
Sometimes I have very similar speed, very similar MAP, similar TPS, same coolant temp with different cell used and with different BLM value (due to the fact that when tha cell switch from a cell with solid BLM 116 value to the 4 cell the ECM remember that the last time in that cell (4) the blm was at a certain value 126).
In addition the cell 4 is used (together to the cell 15 ) also in WOT condition at high RPM .
I know there are boundaries tables related to RPM and MAP value to define which cell is used, but my results do not seems to follow the logic of these tables.
In addition, if the cell 4 is the IDLE cell and I have the constant “Idle max vehicle speed” to 15 mph, why I have this cell active also for speed over this speed limit?
Sorry for all these question.
Thanks for your help.
-Beppe-

 

Very interesting. With your tightly set filters, one would think that you should only data log in one cell. Maybe, the filtering actually crosses the cell boundaries.

Cell 4 is not adjacent to cells 6 & 10 as far as the MAP/RPM cell boudaries are concerned. Also, cell 0 should be your idle cell with a warmed up engine, not cell 4.

When I slowly accel from 0mph to WOT, I track thru cells 0, 1, 5, 6, 10, then either 11 or 14, then finally 15. I have a MAF car with different cell boundaries than you. You will need to get a MAP car person to help with the cells boundaries.

 

RBob? could you chime in?
Maybe i'm not considering some parameter that I should consider?
Thanks
-Beppe-

 

I'm guessing it's the hysteresis between cells. The stock $6E stuff has about 100 RPM of hysteresis, and something like 2-4 gms/sec (on a different computer and don't have the stuff easy to access, so that may be a little or a lot off). This (roughly) means that in order to switch from one block to the next, it has to go 100 RPM above the boundary, and to return to that block it has to go below the boundary (I haven't read the code to figure out if that 100 means 100 above, then 100 below, or 50/50, or 0/100). This prevents a possible oscillation about the boundary that either screws up both blocks, or doesn't let either block learn due to sensor response problems. This means that the same MAP/RPM point can be in 2 cells depending on which direction (RPM and MAP) it was entered from.
I think cell 4 or 6 is a "special" block that is reserved for vapor canister purge or something like that. There used to be a bunch of questions on here like "why does my car always stay in cell 4" or something like that. Maybe you can find the answer in there.

 

Have you tried adjusting the "threshold boundaries" for the BLM Table? You can set it based on MAP and RPM for SD.

I found it best to adjust the thresholds to use as many of the 16 cells of possible based on the type of driving I do where I live.

 

The $8D MAP ECM has cells boundaries at 25, 50 and 80 for MAP and 700, 1200, and 2000 RPM for engine speed. Your filter for MAP is 48 to 52, so by doing this, the ECM will jump between cells 6 and 10 while you drive and accel or slow down a bit.

Also, a scanner can not take data all at the very same exact point in time, there is a data stream at a given speed.

Glenn has a good idea there, as I have moved the cell boudaries on my MAF car in order to spread them out a bit and make more use of more fuel trim cells. I didnt want to get into cell 15 unless I was truely wanted PE mode and WOT conditions.

 

Since you're using the 730 (I'm just guessing because of map) then there is hysteresis and boundries. Stock boundries like doc said are at 50kpa so that explains most of it.

 

Yes you are all right! my filter at Map between 48 and 52 Kpa is the explanation. It's betwen cell 6 and 10.
What I don't understand is the use of the cell 4 .
Cell 4 is the IDLE cell (referring to my bin and refering to the anht_hac.pdf).

My CCP is NOT disbled.

I have cell 4 in all MAP / RPM level (togeter with the others correct cells)!
Example:
Im at 1500 RPM I should see cell 2 (very low map), cell 6 (betwen 25-50) cell 10 (between 50-80) and 14 (over 80 kpa).
.In effect I can see all these cells even considering edge to edge hysteresis, but i can see also the cell 4.
Maybe there is some situation with a "force Idle cell" routine?
I find in the anht_hac.pdf:
Disable idle cell LRN IF CCP DC GT 0
FORCE Idle cell LRN IF CCP DC LT 51. (19,96% DC)
even monitoring the CCP DC the idle cell seems NOT folowing this CODE strategy.
Could someone help me on this?
I have if you want a .uni file from datamster.
it is 1.45 MB with an outlaw "street" 1/4 mile on it....
Could someone explain me how to post it?
Thanks
-Beppe-
Edit:
It seems that when the CCP DC goes over 19.96% it exit from cell 4. (stock AUJUP is 23%)
When it return to cell4?
Under 700 RPM and between 30 to 50 map (as expected from my stock bonduaries MAP RPM tables) AND when I left the gas pedal (tps uder 2.34%) and when the speed decrease to at least 20 MPH.
Example:
I'm running at 40 MPH 5% TPS and I'm in cell 6 as expected and the CCP DC is over 19.96%.
Then I lift the gas pedal, The TPS goes to 0 (or less than 2.34%) the car slows MPH and stays in cell 6. If I continue to stay with TPS UNDER 2.34% up to reach a speed of 20 MPH , then it switch to cell 4 again.
If I use again the gas pedal starting from 19 MPH I have 3 situations:
1) If I use less than 3.13% TPS (The threshold to enable the CCP) I can gain speed (say up to 30 or more) and it stay in cell 4 (even if the speed is GT 20 MPH and the RPM is GT 700 or 1000 or 1500...)
2) I use more than 3.13% the CCP is ENABLED and the DC start to climb up to reach le limit of 19.96% . After this threshold the cell switches from 4 to 6 o 10 or to the cell defined in the tables bonduaries MAP RPM.
3) If i do a WOT sometimes it stays in cell 4 or it goes to 15 .

The strange thing is that I can't find any constant that says that 20 MPH is a lower threshold to switch from a given cell to Idle cell 4.
The only constant I can see that can be related is called in TunerPro "Idle max. vehicle speed" but it is 15 MPH.
(My goal is to lower this speed to 1 or 0 since with my stock cam tha cell 4 is the real idle cell and I want to stay in cell 4 ONLY when the car idles.
.
Hope this Helps someone else, and I hope someone can say if the
constant "Idle max. vehicle speed" is the constant I want to lower to 1 or 0, even if it's 15MPH and it seems to works at 20MPH.
-Beppe-

 

I can't remember but maybe the code does something funky like use cell 4 when in DFCO or enlean. Look at the places where it goes into cell 4 and look at the flags, you might find a connection.
That's my only guess and it wouldn't suprise me if GM did that. They do some weird stuff, they aren't perfect (time crunch). They do usually have reasons though that I can disagree with now that I've had 10 years to find a mistake, lol.