Working with a 16197427 ECM. I've read what I could find in the FAQ's and it seems the BLM is what the ECM uses for fuel corrections directly. My question is this always true for differen't ECM's? Do they all use these tables in the same way? I guess I don't really understand how these two tables work together to make one fuel correction. I know BLM is long term and INT is short but.........?

 

I am starting to get the jest of it finally. I understand that your car uses the INT for Short Term corrections and I think for startup before the O2 sends the system into closed loop. Then your INT will continue to work until your AFR is learned that is when BLM kicks in.. I have noticed if my BLM is 125 which is slightly rich my INT will go above 128 and will bring my BLM back or close to the 128 that it needs to be. Since I am adjusting my fule tables, I still have to correct many of these my self. using the INT / 128 X Map table .. If anyone else finds this to be wrong please chime in and correct me.

 

from what i understand, and i dont swear it to be correct, is that the BLM does make fuel corrections, and the INT sort of makes corrections to the BLM...

BLM above 128 = adding fuel because of lean condition
BLM below 128 = taking fuel away because of rich condition

INT above 128 = BLMs are going to rise
INT below 128 = BLMs are going to fall


I hope someone else can confirm that this is correct. So dont take it as the final answer yet..

 

Thanks for the help guys.
What brought me to this question is the data log from this ECM shows the INT very good almost througout and the BLM's very lean like as high as 172 in some ranges. This doesn't make sence to me but from what I understand the vehicle is actually running lean?

 

If the INT is back to the 128 area then the engine is running stoich (basically). With the BLM at 172 it is adding fuel, quite a bit at that. This is fuel above what the VE tables are adding.

RBob.

 

OK, I think I get it. So the engine isn't in immediate danger but the ECM is doing some major adjustment to keep things in check. I just need to figure out why it's doing all of that adjusting.

 

Hey RBob, is my explanation on the INT/BLM correct then? I suppose so if you didnt have to correct it.

Binder, my stock BLMs are also very high (160 ish), so what im doing before all else is running some seafoam in the gas in hopes to clean possible dirty injectors that may be restricting fuel flow. I aslo want to get a guage to check fuel pressure.

also, i set my injector constant from 19 to 17.5, and the BLMs did get much closer to 128. In the reading i have done, Im not sure if this is the CORRECT way to do it or not, but it was what i expected to happen. Unltil i know more, ill consider the idea of playing with injector constanta temporary thing that will hopefully allow me to pass echeck.

 

OK I'm still trying to learn this stuff. Now what I'm noticing is that the BLM values will sometimes change even in open loop. What I don't get is how BLM can change when BLM enable flag is not on and in open loop? Is it just that the data log is so slow that things are happening in between log points(1227747)?........
What I'm trying to do now is figure out the best way to tune with my WB. Should I just set closed loop RPM and temp enable very high to keep it in closed loop or do I want to set the BLM and INT max/ min settings all to 128? I know I want to turn off the ECM's ability to correct fueling by what it's learned but what's the best way to do this?

 

Which cell is in use is changing. The '7747 has 16 BLM cells.

For WB usage set the closed loop enable temperature max'd, and set the min/max BLM values to 128. May throw an O2 code, so can disable those for no SES light.

RBob.