Hi all, I need a little help guys. I'm attempting a rough tune of my S-AFC off the O2 sensor. I've run into a snag though. I can't seem to figure out what voltage numbers would indicate a proper air fuel ratio. The FSM just says it should read under 1 volt. I'm getting readings of .12- .19 volts, I think this maybe indicating an overly rich condition. If someone has insight to this let me know.

 

umm... .1 is way to lean LOL unless you are talking about idle. should be around .85 or so at WOT. but you really shouldn't be tuning off a normal 02

 

That voltage reading was taken with all the S-AFC's values reading zero. Somethings wrong here. I'm assuming the O2 sensor is bad. I dunno, the engine is definitely running rich with the hi-pressure Walbro installed.

 

normal 02 sensors are like an on off switch. they go from off to on at about 14.7:1 air fuel ratio. plus they are affected by heat. so what you want to see at full throttle is .9. a good way to tell if your 02 is working is to cruise about 60-70mph and see if the voltage changes. it should flop back and forth between rich and lean.

mike

 

That helps explain the low voltage I'm seeing. I haven't run it at wide open throttle yet. Damn pump is putting so much gas in that I can't drive it.