im looking at building a turbo setup over the summer. assuming i get everything working right at 5-7psi would i be able to tune my air/fuel ratios right for my combination and retard my tunning by an email tune if i can put it on a snap on scanner at my work that will read knock, timming, misfires, and o2 readings?

 

anybody tuned there pcm using o2's to test air/fuel ratio?

 

It would be best to get a wideband o2 set-up. The stock o2's are only narrow band which read from around 14.7 A/F ratio, whereas the wideband can read anywhere from 10.1-18.1 A/F ratio.

 

does anyone know what stock o2 voltages correspond to in air/fuel ratios?
thanks

 

You can't correlate narrow-band O2 millivolts to A/F ratio, except in the very narrow range of 14.6-14.8:1. That's what they are designed for. When you go richer, particularly to the rich mixtures you want in a turbo setup (or blower, or nitrous), the narrow-band sensor is operating in an area where the curve of millivolts vs. lambda is very flat..... a very large change in lambda (A/F ratio rleative to stoichiometric) produces a very tiny change in millivolts. On top of that, the millivolt output level is very sensitive to operating temperature, so that a small change in operating temperature will produce a more significant change in millivolt output, than a major change in A/F ratio.

Same answer you got above.... just a little more detail explaining why you can not RELIABLY use a narrow-band O2 sensor to "tune" and engine that requires a rich A/F ratio.

 

would an air/fuel gauge work then? or still not really accurate enough. i know wideband o2's are the best but a little out of my budget so looking at other options.
thanks for explaining that

 

An air/fuel gauge uses the stock O2 sensors to get their numbers...you don't want that.

 

if you're going through all the trouble of a turbo setup, spend the extra 500 and get it dynotuned, i'm sure you'll be more satisfied :P