BLM question
Thread Starter
Racer
Joined: Feb 2009
Posts: 486
Likes: 3
From: el cajon ca
BLM question
hi everyone, i'm working with a tune company on flashing a chip for my 91 vette, they send me the file and i download it on ostrich2 using tunerpro rt 4, and then i data log and e mail them the data log so they correct the tune till i'll be satisfied with the result so then they will burn the chip and send it to me, i kind of know what the blm is and i understand when its 128 it means the O2 sensor is happy with fuel mixture and not trying to correct it, while when its below that like 125 it will mean its running rich and the computer is cutting fuel based on the data the O2 sensor is sending, and when its more than 128 like 135 then it will be the oppesit so the computer will be adding fuel, so how good can it get done? am i supose to see only 128 all the time or there is +5 and -5 in it so between 123 and 133 would be accebtable? or what? thanks a lot
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
128 is for pure gasoline at 14.7:1 AFR. If you use fuel with alcohol in it then the optimum AFR is slightly richer and you can expect the BLMs to reflect that.
Basically the important BLM cells are the ones on the diagonal from 0 to 15. You will spend probably 95% of your time in those cells. Check out this little chart I made. It's for the BUA firmware in my car and GM adjusted the RPM thresholds in later versions, but the principle is the same. As the airflow and RPM go up they track each other and you go from cell 0 to 5 to 10 to 15.
Basically the important BLM cells are the ones on the diagonal from 0 to 15. You will spend probably 95% of your time in those cells. Check out this little chart I made. It's for the BUA firmware in my car and GM adjusted the RPM thresholds in later versions, but the principle is the same. As the airflow and RPM go up they track each other and you go from cell 0 to 5 to 10 to 15.
Code:
; Block Learn Multiplier cell matrix at L001C: ; ; 700 1200 2000 ; RPM RPM RPM ; | | | ; --------------------- ; | 0 | 1 | 2 | 3 | ; ---------------------- 12 gm/sec ; | 4 | 5 | 6 | 7 | ; ---------------------- 22 gm/sec ; | 8 | 9 | 10 | 11 | ; ---------------------- 34 gm/sec ; | 12 | 13 | 14 | 15 | ; ---------------------
Thread Starter
Racer
Joined: Feb 2009
Posts: 486
Likes: 3
From: el cajon ca
ok so + or - 5 would be my goal, but if it would be more than that wouldnt it efect the air to fuel ratio in wot? i mean in part throttle the O2 sensor will monitor and correct the ratio but in wot the computer goes by the whatever the fuel tables says plus the power enrichment percentage added right?
