tip for tuning ve with nbo2 with 107 LCA cams

For discussing MicroSquirt (TM) configuration and tuning of fuel parameters (including idle valves, etc.).
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Alonso
MegaSquirt Newbie
Posts: 5
Joined: Thu Mar 10, 2005 1:39 pm
Location: Merida

tip for tuning ve with nbo2 with 107 LCA cams

Post by Alonso »

Have MsII v2.3abs firmware and v3 board with msd 6a

new discovery for me because i was attempting to tune with O2 at .45 v supposing this was stoichometric this educated guess is wrong for 107 and 108 Lobe separation angle cams.

turns out that i dissabled o2 correction and increased ve table until i reached a stable .8 v signal from the narrow band 02 sensor. engine now runs better at idle and cruise. clean white spark plugs.

so i can conclude that the intake charge contaminates exhaust charge then this fouls the O2 reading in such way that the end result is that .8v means around 15:1 so runing lean with an nbo2 means you are leaner than you think when tight Lobe center angles are used.

HOPE THIS TIPS HELPS EVERYONE WITH TIGHT LCA !!!
<<<<FIREBEETLE 94>>>>>>
Bernard Fife
Super Squirter
Posts: 1009
Joined: Mon Feb 16, 2004 3:15 pm

Post by Bernard Fife »

Alonso,

Voltages above 0.45 indicate rich mixtures with a narrow band sensor, voltage below 0.45 indicate lean.

Image

http://www.megamanual.com/v22manual/mwire.htm#ego

I suspect you are probably around 13 to 13.5:1 at idle (which might give a sensor output of 0.8 Volts), that's where most engines similar to yours like to idle. The best method for tuning idle VE is to aim for miminum kPa, not a specific AFR.

Lance.
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