BLM Cell Boundry Mods??

[BoostKillsStres]

Has anyone ever tried widening the RPM and gm/sec cell boundries for the BLM table?? Its right there in the spreadsheet as 900, 1100, 1400 and 10, 18, 36. I figure possibly more of the BLM map could be used as usually only 8 or 9 of the 16 cells ever learn any new values from the default resets of 128.

Not sure its worth much but would help provide better part throttle fueling resolution.

TIA

 

[Sleeper]

I had raised the RPM and GPS limit to stop the toggling between cell 0 and 1 when I had gone to bigger injectors and had done some fiddling with the MAF tables. It had helped with the idle and transition. I also played with cell 14 and 15 to keep the cruise cell stable. You are right about a lot of the cells not changing, If certain RPM and GPS parameters are not met those cells are not altered.
If you compare the ACXA stock bin to the BBJK emission bin you will see that they have different cell boundary's. The ones you quote are from the BBJK bin.

Paul

 

[dennisL]

FWIW I changed the BLM boundaries for my street car some time ago. I thought the results would be dramatic but they weren't. Paul is right, the stock chip (not recall) uses 800, 1100, and 1500 for RPM; 9, 20 and 30 for MAF.

I changed the RPM to 1000, 1500, and 2000; the MAF to 10, 20, 36. No matter what you change them to you still will always have several cells that never get used. (#4, #8, #12 primarily) The airflow just can't get there without the RPM increasing.

I do like the increased control over idle and low speed driving fuel adjustments that the "pushed out" boundaries provide, since I'm still running closed loop.

I am thinking about "tweaking" the MAF boundaries slightly so they better match the first three MAF tables. (That is what the stock values did). It doesn't make the car run any better, just easier to tune the chip.

 

[BoostKillsStres]

Thanks for the info guys, I did move mine around to 10, 18, 36 and 900, 1400 and 1800 and I was able to pick up 4-5 more cells but it tends to move through some of these rapidly. But at least there getting used.

In my first attempt I set the max rpm to 2200 and it basically just shifted the far right cells to the left one cell so I see what you mean.

Its always interesting finding peices of factory code that needs a little optimizing. Are there any other areas y'all went after to correct that are out of the ordinary?

TIA

 

[dennisL]

Its always interesting finding peices of factory code that needs a little optimizing. Are there any other areas y'all went after to correct that are out of the ordinary?

The most glaring problem (to me anyway) has to do with the idle controls. This includes the startup fuel tables, the target idle rpm tables, and a little IAC stuff. The startup advance tables can be tweaked for a slight improvement.

I've spent considerable time "playing" with all the data values that control idle with a goal of achieving a very smooth warmup and hot engine idle while still using closed loop. The Thrashers are famous for smooth idle but they use open loop.

Maybe you've already fixed the idle for your car, but if not I would do that next. Let me know if you have any questions.