Sale ends todayGet 30% off any course (excluding packages)
Ends in --- --- ---
Forum Posts
Courses
Blog
Tech Articles
Ok bit of a funny one. Confusing for me. I understand lambda and AFR. What's qeurying me is that on quite a few of other people's dyno sheets in F/I applications too. The dyno sheet says the AFR is 11.5:1 full noise on e85.
That's what I worked out to be 1.2 Lambda. Is this not dangerously lean??? It works out the equivalent of 17.64:1 on pump 98
There is so much confusion surrounding this. Most tuners don't understand what's going on and they leave their wideband meter set with the stoich value for pump gas - 14.7:1. In this case the target AFR readings end up the same as what you'd shoot for on pump gas. The wideband doesn't care or know what fuel it is reading and it actually reads natively in lambda - Or to be more accurate if there is an excess of hydrocarbons or oxygen in the exhaust.
So a reading of 11.5:1 on E85 with a stoich setting of 14.7:1 would actually be a lambda of 0.78. If the wideband had the stoich setting changed to 9.8:1 it would then read 7.66:1 which is more realistic for E85.
This is just one reason why I suggest tuning in lambda. There is no chance of confusion creeping in when changing to different fuels with different stoich values.
