BLM/INT question

[Terminal_Crazy]

OL SD = Open Loop Speed Density.
Speed Density is NO MAF, just the VE Tables
You're running CL Closed Loop as you are using the CL feedback from the narrow bands.

IF You are running MAF, I think the VE Tables aren't used & you need to play with the MAF Tables


The integrator hovers around Stoich. PCM counts Cross counts of the Narrowbands going rich & lean.

If it's rich & the INT has moved down by around 5 counts The BLM lowers reducing fueling & the INT tries again.
With the BLM pulling fuel (8-10%) the integrator is hovering around stoich again so is happy.

Mitch

[Kitch]

Thanks again for the reply.

I had guessed SD might have represented speed density :)
No MAF just an old 7427 PCM.

Okay... so the Integrator tries to hover around Stoich!
That now makes more sense and explains why you said I had it the wrong way around.

If I'm understanding this the BLM at 117 is representing where the INT has already pulled it to, so that's why the INT is now in it's happy 128 place?

If you don't mind I now have another question, if the Integrator can move the BLM to operate the engine's EFI at Stoich what's the big advantage in altering the VE table so the BLM ends up close to 128?
I've altered VE tables many times to get it close to get the BLM to show 128 but never thought about the advantage in having it as close as possible to 128 vs letting the Integrator sort it out?

Cheers,
Andrew

[steveo]

block learn mode (blm) is in bigass blocks

it can adjust like 1/4 of the table at a time

it cant change the shape of the table

fine adjustments yeild better drivability overall

also some things dont take blm trims into account

open loop and wide open throttle often dont

blm and int are displayed poorly in almost all gm software you should see it as a percentage to know what's actually going on

[Kitch]

Thanks Steveo,

I think I'm happy with the BLM INT relationship now.

Most of your statements above sound familiar to me.
I'll need to do some more reading up about BLM and the main reason you'd want it to be close to 128.

While I'm getting dumb questions out of the way.
Presumably the PCM saves to memory the changes the INT has made to the BLM, so next time you start your vehicle they're still all there.
If you power-down the PCM or upload a changed .bin file will the BLM/INT learning process starts all over again?
The VE table is a constant that the PCM works with but can't physically change/edit?

Cheers,
Andrew

[dave w]

Sample of a BLM correction spreadsheet.

BLM correction formula = Current BLM / 128

Example shows rich BLM's

BLM Near Idle.jpg

[dave w]

Sample of a BLM correction spreadsheet.

BLM correction formula = Current BLM / 128

Example shows rich BLM's

BLM Near Idle.jpg

VE Fixer Spreadsheet Thread: http://www.gearhead-efi.com/Fuel-Inj...r-Spread-Sheet

[Fast355]

VE Fixer Spreadsheet Thread: http://www.gearhead-efi.com/Fuel-Inj...r-Spread-Sheet

I target a BLM around 124 rather than 128, keep it a little rich and let the PCM and 02 sensor sort it out.

[LeMarky Dissod]

Presumably the PCM saves to memory the changes the INT has made to the BLM, so next time you start your vehicle they're still all there.
If you power-down the PCM or upload a changed .bin file will the BLM/INT learning process starts all over again?

Each pcm has limits to what it keeps from the previous engine run.
In other words, not ALL the changes; some, maybe most - depends on the pcm or what the .bin file allows.
Powering down the pcm or uploading a new .bin file is a fresh start.

The VE table is a constant that the PCM works with but can't physically change/edit?

Exactly.