just currious.. with a closed loop system-
what tuning is there to do for non WOT situations? Aside from timing, isn't a/f governed fairly well byt the O2 sensors?

 

The computer will try and maintain 14.7:1 at part throttle.
You can play with injector constant a little to get the blm's closer to 128 if you want. You could also play with the maf tables to do the same thing.
I have found that the closer the blm's are to 128 the better throttle response is. Noticably better.

 

hmm...
first off i dont even know what a BLM is. I havn't started tuning it yet.
how does this affect A/F / milage ect

 

A/f ratio shouldn't be affected at all. The computer is still trying to achieve that 14.7:1 a/f ratio at part throttle. That's what the block learn does. It will add fuel if it sees that the O2 is continually reading a lean condition. It will pull fuel if the O2 is continually reading a rich condition. You were pretty much right on when you said the O2's take care of the part throttle stuff.
Just remember that a blm higher than 128 is adding fuel and a blm lower than 128 is pulling fuel. Should you choose to do any part throttle tuning it will help you most.
Any questions while you're doing the tuning, feel free to ask.

 

whats a blm

 

You've got LT1edit? What kind of problems are you having?

 

I have tuner cat-
should start tuning next week or so

 

WTF 13 letter word is censored


to finding it brook

 

From http://para.noid.org/~lj/PCM%20Tutorial/PCMtutorial.htm

BLM: The block learn multiplier, aka long term fuel trim, is a value the PCM stores to adjust the injector pulsewidth based on accumulated (or "learned") oxygen sensor feedback. BLM's usually change fairly slowly, if at all. The PCM limits the range of BLM from 108 to 160. Here's a frequent source of confusion: A BLM of 128 means that the PCM is calculating the right injector pulsewidth. A BLM below 128 means that the PCM has to take out fuel to get the mixture right (the PCM calibration is too rich). A BLM above 128 means that the PCM has to add fuel to get the mixture right (the PCM calibration is too lean).

One way to remember which is rich and which is lean requires that you can remember that 128 is ideal. You get numbers less than 128 by subtracting - when the BLM is less than 128, the PCM is subtracting fuel. You get numbers above 128 by adding - when the BLM is above 128 the PCM is adding fuel.

Another misconception: In general there is nothing wrong with the BLMs not being 128. As long as they don't reach their limits of 108 or 160, the PCM will be able to get the fuel mixture just right. The exception to this is covered on the Split BLM page. All that said, many of us like to tinker with the PCM until we gat the BLMs as close to 128 as we can, just cuz...