ideal readings for your 02 sensors

[mike malloy]

with the maft+ you are able to adjust your a/f ratio's timing,, etc. with doing all this and using autotap to see what you are adjusting, whta is the ideal range that you want to keep your o2 sensors in.

is this how you tell whether you are running lean or not. with timing how far can you advance it before you see a knock. i know every car is different but i'm looking for ballpark numbers. any help would be apperaited.

for track use how lean can you go before you reach the danger zone, ie.. 02 readings of .800...

[mike malloy]

anyone?

[strange_trp]

O2 sensor really won't help you at wide-open throttle, when the pcm goes into driver-commanded open-loop operation. in this mode it doesn't look at O2S signals.
ideally, you'd want O2S signal (precat) to fluctuate rapidly between around .2vAC to .8vAC.
high voltage from O2S, you're running rich, low voltage from O2S, you're running lean. ALTHOUGH, a steady low O2S voltage may be the result of a misfire.
as far as ignition timing goes, it depends on engine load. you can kick it up to nearly 50 deg btdc with the vehicle in Park just revving high without much detonation, but under a load (WOT acceleration on flat surface) i'd stay under around 28 deg btdc. you may need higher octane fuel the more you increase ign timing advance to reduce detonation when going uphill or otherwise loading the engine heavily.
play with it and see what works best for you.

[DEE97GTP]

Be very careful leaning it out. The stock narrow band O2's are a very crude and potentially dangerous way to tune. If you are serious in tuning it to the max, get a dyno session with a wideband O2. And .8 does sound pretty lean....

<blockquote>quote:</font><hr> O2 sensor really won't help you at wide-open throttle, when the pcm goes into driver-commanded open-loop operation. in this mode it doesn't look at O2S signals.
ideally, you'd want O2S signal (precat) to fluctuate rapidly between around .2vAC to .8vAC.
high voltage from O2S, you're running rich, low voltage from O2S, you're running lean. <hr></blockquote>

Yes the PCM goes into open loop, but the sensor is still working. At idle or low rpm, this cycling is true. But at WOT, you do not want this cycling. It is a very vague explanation that a high voltage means your running rich. Or visa-versa.

DEE

[strange_trp]

<blockquote>quote:</font><hr>Originally posted by DEE97GTP:
Yes the PCM goes into open loop, but the sensor is still working. At idle or low rpm, this cycling is true. But at WOT, you do not want this cycling. It is a very vague explanation that a high voltage means your running rich. Or visa-versa.
DEE<hr></blockquote>

what i meant was that at WOT the PCM does not look at O2S signal for fuel trim decisions. in open-loop, even driver-commanded open loop, the PCM looks at engine load sensors to determine fuel trim. sure the O2S signal will still respond to changes in fuel mixture even at WOT. the O2S will respond any time they are 600degF or hotter. the PCM just does not consider this signal at WOT for fuel delivery.

you are correct that the O2S signal should not vary nearly as much at WOT, for this very reason. it is not being used for fuel trim, and at WOT you'd expect to see O2 voltages in the richer range (fluctuates but skewed a bit over .500 vAC).

an O2S reading around .800 vAC would indicate a very rich a:f mixture, not a lean one. however, you are correct that you do not want to run the engine too lean under any condition. detonation will increase as will NOx emissions.

my explanation of O2S readings (low volts = lean a:f mixture) was indeed an overly simplistic one. there are many other things other than a:f mixture that can influence O2S response, and many of these can actually result in a false O2S response. I was just using that simplistic explanation as a foundation...

[ March 13, 2002: Message edited by: strange_trp ]</p>

[mike malloy]

thanks guys, anyone know where there is a dynojet in south georgia, or jacksonsville or tallassahee

[Magnus]

With an NA setup, and our relatively lower compression.. its not as hard on the motor to run real lean...

But still you should avoid it.

I've made WOT passes @ 0.100 mv o2's.. :(

I run records around .850 o2's.. NA only..

Nitrous i was shooting for .910 min..

But as said before, the O2 sensors are not very accurate and its best to use a wide band O2 sensor for tuning.

[strange_trp]

<blockquote>quote:</font><hr>Originally posted by Magnus:

But as said before, the O2 sensors are not very accurate and its best to use a wide band O2 sensor for tuning.<hr></blockquote>

true.
even better to have a 5-gas analyzer there for tuning. if you (or the dyno shop) has the $$$ for one, that is...