megasquirt surging issue solved

[marc79euro645]

I've had a problem with surging when decelerating around 1600 rpm. I remember a thread recently about that, and I advised to richen to help mask. This is what I thought mega manual suggest,setting the decel fuel rate high 90-100 thing my%.
It did help.
Then I tried smoothing my spark map in the area. That helped some too, but still surged at times,causing me to clutch to mask.

I finally solved the surge completely by reworking my ve map to include a 20 kpa level,previously I only went down to 30 kpa. I thought that was low enough as I idle at about 40 kpa.
I zeroed all the 20 kpa cells,but keep decel at 100%.
Now when I lift while cruising my afr quickly leans, which should help with mileage, and no more surge.
I love megasquirt !
marc

[turbodan]

I've read in the Megamanual that you don't want to set VE cells to zero with MS. Apparently it can cause unpredictable pulsewidths.

What kind of ignition advance are you running in the area the surging occurs?

[marc79euro645]

I've pulled timing back to 10 btdc @20kpa, but I idle at 20 btdc @ 40 kpa.
I think your right about it not liking zero on the ve,I think I'll change that to 1.
Data logs show low of 26 kpa when decelerating, so I doubt it would get all the way down to 20 kpa (zero on the ve),
but good advice.
thanks
marc