Lambda commanded vs WB & stoich

[lee82]

So the equivalence ratio lambda commanded is always about .06-.07 higher than the equivalence ratio lamba at the WB sensors on both banks, at idle, cruise, and WOT. I have a third AEM sensor as well that confirms this. IE, at idle and part throttle my widebands are reading 1.00 and I'm usually around 1.06 commanded. At WOT I'll read .82-.83 at the wideband and have .89-.90 commanded. My actual lambda table for WOT is of course set to .82-.83.

Is this because my stoich is set to 14.08 but I'm actually running ethanol free gasoline? I read in Lasota's book that I should change this to 14.6 if I'm using pure gasoline, but at the end of the day does it matter? Also, is there any real advantage to E10?

[Samoflan]

Pretty much sounds like you might of answered your own question. Did you ever change the stoich back to 14.64 to see if this made any difference?

There is also no advantage to E10. It's what 99% of the pumps you come across are going to carry. Any station that has ethanol free fuel will advertise it and is going to charge you a premium.

[Grim5.0]

agreed sounds like you found your answer. its adding more fuel through the stoich multiplier, id try as recommended to change to match the fuel content in the car.

i pull a sample and check the e content with a graduate cylinder if in doubt and looking to adjust using fuel trims too. same reason when all fueling error gets mixed into the maft curve guys think the 52ftlb on their gen2 is a sign of success (but the period remained the same or minimal change). several ways to increase/decrease fueling and then adjust for it with airflow.

[rzabsky]

Hi,
I have a simple question. TO change the stoich afr if you use a different fuel - is it enough to only change in Fuel->General->Stoich AFR, or should also change it elsewhere?

[decipha]

nope that's it

On all the coyotes I tune I always set the stoich to 15 and compensate in the injector data so the gauge cluster displays typical AFR values regardless if E-85, E-10 or pure gasoline.

[rzabsky]

Thanks!