why is stoich for gas vehicles slightly different in different os's??

[S2H]

its correcting to match the o2 switching voltages...

the o2...at lambada 1.0
outputs a specific voltage..which is programmed into our pcm in a table

[xonelith]

its correcting to match the o2 switching voltages...

the o2...at lambada 1.0
outputs a specific voltage..which is programmed into our pcm in a table

Sorry, maybe I'm being dumb, but can we correct these in a V6? Which table? I think what you're saying is, it's attempting to keep the voltage of the o2 sensor at 500 (other than PE, before AE), right?

I guess this is where I get confused. Even if I increase the amount of air coming in, the o2 will read lean, causing the LTFT's to run positive. I suppose this is why you have modified yours to be a wideband

Geez, I gotta lot of learning to do...LOL

[xonelith]

I think I got it figured...

Changing the stoichemetric, should change what the o2 sensor is reading as 500. Increasing this (assuming no cat) would change what the LTFT's are correcting to.

I'll test this out and post any results (once I get my cable)

[EC_Tune]

I think I got it figured...

Changing the stoichemetric, should change what the o2 sensor is reading as 500. Increasing this (assuming no cat) would change what the LTFT's are correcting to.

I'll test this out and post any results (once I get my cable)

The 02's are doped to read 451 mVdc at ~14.6 - 14.7 AFR. I had (RIP) a reliable source that GM was doping the 02's to achieve specific AFR under lab conditions. (Oooohhh the controversy of doping arises!)

This *may* account for the slightly different Stoch AFR values. Or maybe GM is just playing around with the values...

EC

[xonelith]

The 02's are doped to read 451 mVdc at ~14.6 - 14.7 AFR. I had (RIP) a reliable source that GM was doping the 02's to achieve specific AFR under lab conditions. (Oooohhh the controversy of doping arises!)

I'm guessing that changing the stoichemetric value in HPT could change this to 'read 451 mVdc at ~xx.x'. I'm going to test this out. Hopefully so

This *may* account for the slightly different Stoch AFR values. Or maybe GM is just playing around with the values...

EC

Someone had also told me that the difference in stoich values could be due to the different additives in the higher octane gas. My car, from the factory requires 87, whereas I think the V8's require a little more, same with the boosted 6's. Also, something to do with the catalytic converters.

[MNR-0]

Or more likely it was the fuel used when calibrating the test car for emissions compliance

Old thread, I know, but with bio-fuels coming into their own some useful stuff here worth of a bump, even after 3 years