Short term BLM and Long term BLM

[Nathen]

With a map PCM I understand thet the PCM maps RPM against MAP and looks up the VE table to get the amount of air entering the engine, then It uses the BLM to adjust the the VE
So with a Maf PCM the Air is measured not caculated and the BLM adjust the ?? to get the correct ratio.
So my question is what is the differance between the Long term BLM and the short term BLM

[VL400]

They actually both do the same thing. The MAP ECMs do not directly change a VE value to trim the fuel, they apply another plus/minus % correction during the fuel pulse width calc, the MAF PCMs do exactly the same during its pulse width calc.

Long term trims use the BLM (Block Learn Multiplier) and short term use the INT (integrator). During closed loop fast changes are made to the INT (either up or down depending on if its too lean or rich) when they reach a threshold the BLM gets incremented or decremented and the INT is reset to 0% correction. The process starts over adjusting the INT and if needed the BLM until the engine is running at the stoich AFR.

The BLMs are saved in a table, so are learnt and remembered when you turn off the engine. There are limits to how much the BLM is allowed to adjust.

[Nathen]

Thanks Great information, I had an inclination that was the case, Where can you find the limits for thr BLM and the threshold for the INT.

[antus]

and i'll answer your question with a question - do you think the stock values are not good?

[Nathen]

I am messing around with a factory Lpg Vy, Which has a BLM of 50, (On LPG) I was thinking that was high, thats all, so I need to figure out if it is high and weather that relates to another problem. So to understand what "High" is a good place to start is what is the limit.
If it is High it confirms what I think the problem is.
Does that make any sense at all

[antus]

yeah, it depends on the adx, no trims are half way, thats usually either 100 or 128 depending on the adx (the raw value is 0-255, so a raw half way is 128, or it can have a calculation to make it a % where 100 is no trims). Usually trims in either direction would be < 10. So 50 sounds very wrong to me.

[Nathen]

Where Can I find information on how the ADX interprets data and calculates values. The Long and short term trims are in % according to value table in the adx editor . I am using yoda TP5v1.04

[Nathen]

OK so I followed a hunch and opened the adx in notepad. look at that it is a text file. searched for long term trim. Found a section that has Math equation = X-128
I am assuming X is the raw value 0 -256.
so the displayed values would be -128 to 128 with 0 being neutral (128 or no adjustment)
Is this correct and If so how does it scale it to percent.

[Holden202T]

you can also in tunerpro click on the two gears on the menu to edit the ADX, then go into values and there is a conversion tab at the bottom which shows how the calculations are done.

some people setup the adx to show the blm in the method you have listed above, but I prefer it as a percentage of 100 so you can use it as a direct conversion to the VE table ... and that calc is (x * .7815) - .032

each to their own I guess

also i'd suggest not editing the ADX in notepad, you can easily corrupt it, but you can do everything you need in tunerpro with a nice gui so its its all good!

[EagleMark]

(X - 128) / 1.28