Synapsis

So I'm slacking off at work, reading anht_hac.pdf, and I come across the block learn chart on page 39. I've noticed that on this calibration, the low boundary is 28 Kpa, the mid is 36 Kpa and 45 Kpa.

Now if GM set these boundaries for sea level, that would explain why I idle in cell 4. I'm at around 3100 feet in altitude, which is a 12.8 Kpa difference from sea level (all other things equal.) The difference between cells is 8 Kpa with a 2 Kpa hysterisis.

My question is: Would it be beneficial to adjust the BLM boundaries so that I'd idle in cell 0.. and get more "resolution" to work with throughout the driving range? With more "resolution" (i.e., more cells to tune) I could get smoother running when going from cell to cell, right?

This is what happens when I'm bored at work and have cars on the brain.

Grim Reaper

Cell 4 is a "special cell". Trust me, I've played with it and adjusted ALL of the boundaries (not necessarily a bad thing which I will explain in a second). But when your car is idling or in WOT on an SD car, you will ALWAYS go to Cell 4. Play with it, but you will find that I tell no lies.

Now, as for adjusting those boundaries, by all mean do so. I found that the stock settings did not use as many of the possible 16 cells as it could have. The top boundary should be set to your highest "cruising" rpm so you can use it on the highway and it doesn't make too much sense to have combos that never result in a cell being use. The more cells you can utilize, the more you can take advantage of the "learn" feature.

But, in all honesty, once you calibration is "damn close" to 128/128 perfect, the BLM has minimal value IMO. But it is nice to use a lot more of the cells.

Let me know if you EVER get it to use Cell 0 while idling. I have hit cell 0, but not in idle.

Synapsis

I'll screw around with it then. The lowest cell I've hit it is 2, and that was right after I took my foot off the pedal after cruising. I've noticed that I'm in cell 4 90% of the time the car is on, but I also idle at 31-33 Kpa after the car's warmed up. I'll keep you posted.

Synapsis

I found where the idle cell # is determined, and in anht_hac it's set to cell 4. It's on page 39, L8527.

I don't know if I want to idle in cell 0 anymore. Looking over the commented code it seems like cell 0 gets special treatment when it comes to learning. It only gets to learn for 30 seconds. From the short time I've been going over this, it looks like a keep-alive cell of some sort, which would make sense since I've only been under cell 4 during decel.

I'll keep reading up on how decel works and see how feasible it'd be to switch idle to cell 0.