i noticed some times i will have rising short term blm's and
at the same time declining long term blm's . it looks like long terms
are just sampling the short terms to come up with its number and
that might cause it for 1 or 2 samples if short terms had been falling but i would think that it not continue for 5 or 6 samples . i have most blm's in the 120-135 range now ( except for some light acceleration ) but sometimes the long term still drops into the 115 range . am i understanding how this is supposed to work ?

 

Basically the Short term(INT) are updated at real time or close to it.

The long term BLm are updated every 2-2.5 seconds using info supplied from the short term in most masks that I know of.(assuming closed loop operation is present)

If u chase the INT u will go nuts :-)(in other than steady state cruise)

The BLM is what u need to be more concerned with as it sounds likeu have just began to enter the tuning world.

U have lots of things that influence the INT and in turn the BLM.

AE will make the INT drop like a rock(usually rich) or if u dont have enough on a lrager cubed setup it might even make the int go lean.

If it is a condition that exists any longer than momentary the long term will do the correction.

This is pretty much as simplieifed as I can explain it, it has been written about a time or two and a search will prolly yeild a few more nuggets of info.

later
Jeremy

 

not that it matters but this is on a 749 ecu in
my typhoon . while tuning on the 730 ecu in my
formula i never had this occurr .

you are correct that i am just getting started on
tuning more than just bolt ons on the 749 ecu .
the bigger turbo - cam - heads is giving me fits
with the extra airflow at light throttle before
there is any meaningful boost .

i understand more now about looking at long
term blm's first and then get concerened about
short term stuff after looking thru some searches .

thanxs for the explanation .

more questions to come i am sure .

 

The stock settings for the Turbo trucks were kind of odd, in that they use a ton of AE, and then once that runs out they go lean (well depending on the mods you've made). So you want to watch the O2 closely to see what's going on. If your's starts to fade like there's a timer at work try less AE, and more PE fuel....
You maybe OK, that's just something to watch for.

 

In a nutshell, the INTegrator is what makes the desired fueling changes in the closed loop algorithm. The BLM is actually used to store actual corrections to the fueling to compensate for anything being off (humid night, VE off, MAF table off, bad sensor, etc.). The INT may be ok even though you have BLMs of 108 because the BLMs are compensating for the fueling being off so the integrator and proportional terms can do thier job. The BLMs are what actually tells you how far off the fueling is based on O2 readings.

 

just to let you guys know what i am working
on , the truck is richest on deceleration , the
truck is leanest after the throttle is opened
a little and held there ( accelerate from 20-30 mph )
after the turbo start to go positive pressure
everything is pretty good .