Quote:
Originally Posted by Ecky
This afternoon I flashed a new experimental lean burn tune. From 1000-2500rpm, 0-500mbar, I'm running 1.2 lambda (17.62:1), and from 5-600 it's 1.1 lambda (16.17:1), with 5° and 2.5° of ignition timing added respectively.
I found the software's soft limit to be ~1.2 lambda. I can "trick" it into allowing me to flash a much leaner tune, but if I save and reopen my calibration in software, it resets back down to 1.2 lambda.
Even at that lean AFR, cruising, I'm seeing only around 360mbar, and I can climb pretty steep highway grades at <500mbar in 6th - even with gearing that puts me around ~1700rpm @ 50mph.
On my way home from shopping I averaged a hair over 64mpg, with a target speed of just over 50mph. I'd say in exactly equivalent conditions, this first attempt at a leaner tune is worth very roughly 3-5mpg, or approximately 6-7% better fuel economy.
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I'm running about 1.2 lambda without problems, but on E85.
It's quite difficult to get a stable 1.2 or 1.25 lambda, because injector pulse width maps are quite bad for optimizing air-to-fuel ratio without use of lambda sensor.. so it's around 1.15-1.22, would like to try leaner but then it'll start bogging when sudden throttle changes.
But I have tried to run it around lambda=1.50 on low load but was prone to missfiring (sudden load/throttle increases).. and another problem was my wideband lambda which doesn't show leaner than lambda=1.50
It's a load x rpm map.
E.g load=200 and rpm=2500, then the next cell for load is 130 or 250.