set stoich to 15.5 afr and adjust o2 switch points to match, will this work?

[jaykebab]

ls1 5.7 litre

set stoich to 15.5 afr and adjust o2 switch points to match using wideband , will this work?

obviously upping the timing to suit

im running maffless so i thought if i did this i could get better economy whilst not changing the ve so i dont screw the airflow calcs

i know i would need to adjust my pe to suit also

i thought this would be better than cruise lean as when using cruise lean it stops trimming

any thoughts?

[SSUte01]

A narrow band is a lambda sensor, so it will do its best at reacting the actual fuelling to maintain lambda of 1 ie stoich. So, by setting your stoich ratio in the tune to 15.5 will certainly result in a smaller injPW compared to 14.68 or whatever it was initially, but the narrow bands in closed loop will trim back to the actual stoich of the fuel. All that you will achieve by changing nothing other than your stoich value with all other variables the same, is to get more positive fuel trims, this is assuming closed loop obviously. This in itself may cause a slight improvement in economy as the narrow bands are reactive, but if you have LTFTs enabled, it will quickly make no difference. Long story short is you will make little to no difference to your closed loop fuelling by doing what you propose.

I should expand and say that by lowering the switch points to try and achieve an actual lambda of 1.07 or whatever you choose can sometimes work, however I've found, as is the nature of the output of a narrowband, is that away from lambda with the switch points lowered, it is too inconsistent. So, your new "lambda" tends to vary a bit depending on the variables. By all means give it a go, but IMO you won't get a consistent leaner result and you're fudging with one of the fundamental values of the tune. I believe you'd be better off leaving stoich set for the fuel and either lowering the switch points to see what you can achieve or simply tune the areas in the airflow model based on rpm and MAP to achieve slightly positive trims. Let us know how it works out.