Need more stable voltage for APSX Wideband

[johnwohl]

Im trying to get an APSX wideband working and I'm having a problem where the gauge/controller display keeps cycling between a seemingly correct afr and displaying "a 0" like it is reseting every second, or only displaying a correct afr for a minute and then slowly going to 9.0, or flickering between correct afr and 9.0 or just reading 9.0 all the time.

I think the problem is that the 12v isn't stable enough.  I've upgraded the battery, converted to full wave, put my headlights on dc and on a switch, and put a 3300uF 50v cap in between the pos and neg of the controller.

what else can I do or am I even on the right track

[christopher]

Did you wire it directly to the battery? That should clean up the +12 volts, your capacitor to ground should also. How's the sensor grounded? if it uses the pipe add a ground there also. 

[GrumpyUnk]

How much of the exhaust diameter is taken up by the probe? Could it be blocking flow until backpressure rises?
I am not familiar with any wideband personally. I did watch several youtube videos done by someone who lives in CO or UT and has tuned his carb, changing jetting with the seasons. He was pretty meticulous with his test procedures and his results seem to bear that out. I think he was getting really high miles per gallon, FWIW.
As I understand, there are two 12V systems, one with a top-voltage regulator, and one that is rectified and fed back to the battery and other instruments that need solid voltage. The former is used for the lighting circuits and perhaps the enrichment probe winding. The latter for fuel gauge, and perhaps cluster lights.
Either way, I'd get a VOM and put it on both circuits, rev the engine and see how the voltage tracks. You could check the primary windings in the stator, and gang them together feeding a better rectifier/regulator, such as the one used on the CV model Kohler engines. I understand Harley owners use them instead of factory parts as they are rugged, cheap, and handle the load. There are a few videos on how to wire the stator to get a full wave rectifier working. I'd expect that to be a more solid voltage source than what comes from the factory.
tom

[christopher]

Did you ever get this working, thinking it would help with tuning carb.