Air to fuel ratio
 

I was in a friends Niissan Sentra SE R Spec-v the other day. He had a wide band O2 sensor installed and a little screen with the readout and a knob on it. He said that he could adjust his A/F ratio by turning the knob. Now I know just enough to know what all that means, but will that actually help anything. Besides from not knowing what you're doing, I know that running too lean or too rich would be a bad thing. Anyone have any experience with these things? I'm assuming the unit with the knob just changes the resistance values that the O2 sensor sends to the ECU, thereby changing the A/F ratio. He doesn't have a turbo or anything, but it is cammed rather mildly.

I would imagine with mild cams, ajusting the A/F ratio would be usefull depending on how you plan on driving.

generally speaking unless it's a fully programmable system in a tiny little package, it may be able to change the reading the O2 sends to the computer, but the bigger question is, does it do so in a progressive manner? In order to properly tune, there are different O2 values that need to be addressed based on air flow, not on a singular adjustment across the band in a linear manner. Proper tuning is done based off MAP readings, so you can add a litttle fuel under low load, and add a lot of fuel under high load, if you see what I mean. It would be more helpful to know what model WBO2 system he's using to better explain what it's doing. Some have a knob on it that's just for changing what is displayed, rather than for adding or detracting fuel.

Proper tuning is based off air-fuel ratio percent error in a MAP vs. RPM table, at least with the speed density setup on mine.

As BJ said, there's no overall adjustment, it's very specific, very individual for each condition the engine runs. Sounds kinda funny he has a magic knob to adjust the air-fuel ratio real time.

maybe he gets in his car and as he is WOT he adjust the knob.....

why do you want to adjust it?.....Im tuned at a safe A/F ratio...I dont think there is a need to adjust some more...unless you want to push it to the limit =S

I agree. I don't buy this "magic knob that he can turn to adjust A/F ratio on the fly". You should ask him what exactly he is using.

the makers just installed a rheostat on the sensor, as it meets the readout. So as you turn it, its adjusting the readout... but nothing else. :lol:

turn knob = moar powerz!

Attachment 7096

heheheheh

ahahahaha^^^

Next time I see him I'll have to ask. I didn't really feel any time of difference when he adjusted it, but then again, I wasn't driving either.