AFR Calculating

[havalanche]

OK, something isn't quite making sense when calculating AFR. I haven't gotten to the tuning of it yet, and probably won't until I get a wideband.....

But, if I'm reading things correctly, to calculate the AFR being used, I would divide the Stoich AFR (14.7) by the PE Table. The values in my table run from 1.148-1.336. That would give me AFR values from 11.0-12.8. To me, that seems to be running rich. Would running leaner react better? It would have to help the gas mileage. Of course, I didn't by an Avalanche for it's gas mileage - but I would like to increase it a some.....

My VE table is set, my LTFT's are running +2 to -4. So, what, if anything, should I do to adjust the AFR to get it in range? The MAF table is in progess of being tuned, and will hopefully be done this week.

[chrisj6]

i have used my wideband to tune my VE to +1 - -2 and am currently working on my MAF table. I have only done one pass on my MAF table and it got considerably closer and looks like its going to be much easier to tune. My AFR is 12.7-13.1, I wont go lower than mid 12's, it just seems the truck pulls harder when its a hair leaner, 11.0 is way too rich for your setup.

Chris

[havalanche]

The values in the PE table are the stock values.....I haven't touched them.

But, I also know that touching an item I don't understand could hurt the motor, and I don't need that right now.

So, I'm thinking that there is something more to calculating the running AFR other than the Stoich/PE Table values.....It doesn't make sense that they would be set that rich.

Unless you are an oil executive and are trying to cash in on more profits.....

[Zick]

Havalanche, aren't you FI?
If not, then yes that would be on the rich side.
I wouldn't really mess with PE until you get yourself a WB. Its just too hard to try and adjust it by the NB sensors. I know it can be done, but I wouldn't.
There are other things that can throw off the final A/F ratio besides the numbers in the PE table. So even if it says you will have 12.8 A/F, you may end up being higher or lower depending on things.

[havalanche]

No FI as of yet.....It is on my WANT list.....

Right now, I'm just trying to get the most out of what I've got.....