Predator question

[coop5885]

i was scanning my car with my predator and when i went WOT the O2's were reading .905. Is this too rich, and if it is what should i do about it?

Also another random question, did james from runningwiththedevil make it over here?

[xx02]

isn't .905 just the voltage the 02 sensor is getting?

[PC PaiN]

at WOT i don't think the O2's are used as far as A/F

[JandJsTA]

Here is a cross reference of voltage to @ A/F .880-.890 is good


millivolts - a/f
-----------------
930mV = 12.00
920mV = 12.25
910mV = 12.50
895mV = 12.85
880mV = 13.20
450mV = 14.70

Some great reading here http://www.vetteguru.com/mods/howto

and yes you are correct in open loop the O2s are not used for A/F but we can use the readings for appox A/F :)

[drptopz]

Please don't rely on stock O2's for a/f ratio at WOT. The are made to be very accurate at 14.7:1. The farther away from this, the more in-accurate they are. I have seen some that read as high as 900mv at 12.5:1 and some as low as 750mv at 12.5:1.

There is a nice wideband O2 setup just offered that uses the same O2 sensor as my Motec. Check it out at http://www.innovatemotorsports.com/

Dave
DynoTune, Inc
www.dynotune.com

[JandJsTA]

Originally posted by drptopz
Please don't rely on stock O2's for a/f ratio at WOT. The are made to be very accurate at 14.7:1. The farther away from this, the more in-accurate they are. I have seen some that read as high as 900mv at 12.5:1 and some as low as 750mv at 12.5:1.

There is a nice wideband O2 setup just offered that uses the same O2 sensor as my Motec. Check it out at http://www.innovatemotorsports.com/

Dave
DynoTune, Inc
www.dynotune.com

Yes Dave, all to often we like to get comfortable with the thought that because we can read the O2s at PE, lets use them ( it's easier then gettin a dyno done or puttin a bung and sensor in) but the only way of attaining accurate readings are through a wide band :thumbup:

[jimmyblue]

If this is a "normal" car with normal stock exhaust
manifolds and close-coupled O2 sensors, then this
is right where you want to be.

If you want to "find the range", jack the power
enrichment all the way up and do another WOT
pull; you should see the O2 volts higher and this
will be near the "saturated" output value. Now,
go find one of those O2 volts-vs-mixture-with-
temperature charts - like, say, here...

http://community.webshots.com/album/74289894mbMeMp

Start at the left, maybe about the 11:1 point, make
a dot where you had read the fat O2s. From there,
follow the closest line, drawing another parallel to it
(on a printout*) starting from your personal "fat
datapoint".

* Joke: How can you tell the blonde has been using the
computer?

This line first-order takes out your car's temperature
variation (more significant than the AFR-related volts
deflection, where things are fat).

Now, go back to the original PE settings and use your
personal curve to find the best-guess AFR. Odds are on
a stock vehicle the table posted previously is not far
off. Inconsistency comes in when the O2s are aged, cold
(or grossly hot), poisoned. GM put them up close because
that's where they act most normal, which is what that
table represents. Non-stock exhaust is the best way
to get off the track (colder).

Yeah, there's a right way to do it and this is only a
shade tree second-best. But you still can finish "in
the money" without spending a load of it.