Just wondering if changing the constant programmed target AFR for an OBD1 LT1 will affect the gas mileage in hopes of getting better mpg with rising fuel costs?
Seems like I saw this value in the Constant tables...don't have it in front of me to verify...seems like if I made this a leaner value, then the BLM values would drop well below 128 causing it to cut more fuel at cruise speeds and give me better fuel economy...at least lower it to a point to where I'm still not getting any knock as I'm sure the factory setting is a bit on the rich side.
I guess if that worked then I could later go back and readjust the MAF tables to give me the near 128 BLM reading at different cruise speeds/rpms and load.

Or am I just dreaming??

 

Yes and no.

There is an open loop vs. target AFR table you can alter. This is only effective in open loop of course. You can gain a little better fuel economy by locking the car into open loop and carefully tuning this table (with the help of a wideband). During cruise you can run a bit leaner than stoich.

In closed loop, the PCM uses 14.7:1 in its math to determine how much fuel to add, depending on incoming air charge. Even if you could change this it wouldn't help, it would simply throw the initial calculations off but it would be corrected by the BLM's. This is the whole point of closed loop. O2 sensors don't know what value stoich. is, they simply switch at stoich. whatever it may be