Join Date: May 2004
Location: Toronto, Canada
I am not sure how well the autotune will work at extremely low throttle openings. It's very close to the deceleration fuel cut point, which may confuse it. But, I've never messed with it. I did mine the old fashioned way, by watching a gauge and making manual adjustments. I suspect that the autotune will get it in the ballpark but you'll have to make manual adjustments right at the bottom.
What is it recommending for a percent-change in fuel delivery in that region? If it's erratic, the decel fuel cut may be confusing it. Look at the trend from 10% to 5% to 2%, whatever that trend is should continue all the way down to 0%.
Also, do you have the air-injection blocked off? It has to be blocked for the lambda sensor to give a correct reading.
The on/off throttle snatchiness will be worst in the vicinity of stoichiometric. Don't be afraid to lean it out down there. Lean misfire is north of 18:1, and at such light engine load it's quite safe to be just short of lean misfire. You intentionally want to reduce the power of the engine just as the fuel comes back on after deceleration fuel cut - that's how you can smooth it out - lean it out so that when the fuel comes back on, the engine makes hardly any power - presto, less snatchiness.
At next to no engine load, mine is in the 16:1 - 17:1 range (on a gauge, not using autotune).
Be prepared for a lot of fiddling to get this right. It takes far longer to get this right, than it does to get full throttle right.
I did a fair bit of my calibration on a steep downhill, because then it was possible to have the engine at various speeds in deceleration and note what happens on the gauge coming in and out of decel fuel cut.
Helibars, MRA screen, Ohlins damper, reversed shift pattern, sorted suspension, braided lines, Michelin Pilot Power, all else stock 'coz it's fast enough!