O2 voltage readings off? Periodic 0 reading

[Enilator]

Well i got my datalogger this weekend and started doing some logs and monitoring. The only real problem i see is a little high knock at times and my O2 voltage will jump all over the board. It will be around .7-.8 or so then all of a sudden it will go .0-.1 and then back up to .7-.8 like nothing happened. The O2 is newer (6 months/4000 miles). Is it still possible its bad?? I have thought I could have some ECU problems could that cause O2 voltage irregularities?

 

[Michael Z.]

02 readings are supposed to fluctuate. When you are at 100% throttle, what reading are you getting? Those are the important ones. When you are at part throttle or idling, the normal behavior of your 02 readings is to cycle between rich and lean. If you are seeing .7 or .8 at full throttle, you are running too lean at WOT, which is probably why you're seeing knock. When you log, do a WOT run in 3rd or 4th gear, from 3000-7000rpm. Based on your knock and 02 readings, you richen or lean out the fuel mixture. 1Gs generally tune for knock, 2Gs generally tune for 02 readings. There is plenty of information out there for fuel tuning.

 

[Enilator]

Well i just had my wife send me a log i did this weekend and it looks as though even at WOT the voltage is fluctuating and reading .00 at times, so is the O2 dead?

 

[Enilator]

Thought i might put some of the log in here for anyone that can help.

O2 RPM Knock Timing
0.76V 1000 0 13°
0.02V 1625 0 15°
0.02V 2188 1 23°
0.66V 2344 1 28°
0.68V 2375 0 28°
0.72V 2406 0 29°
0.39V 2344 0 29°
0.18V 2563 0 29°
0.78V 2969 0 28°
0.31V 3438 0 28°
0.84V 4063 0 27°
0.86V 4813 1 24°
0.86V 5500 0 23°
0.90V 5500 0 28°
0.64V 4000 0 45°
0.82V 3906 0 26°
0.78V 4250 7 18°
0.80V 4750 11 15°
0.80V 5250 10 15°
0.80V 5625 17 17°
0.80V 6063 23 17°
0.78V 6375 22 15°
0.76V 6625 24 13°
0.76V 6813 23 11°
0.78V 6656 22 10°
0.68V 5719 0 41°
0.74V 4906 15 25°
0.00V 4969 14 14°
0.00V 5188 13 14°
0.00V 5313 12 15°
0.00V 5438 20 17°
0.00V 5656 19 15°
0.00V 5719 25 16°
0.00V 5938 25 14°
0.00V 6000 24 15°
0.00V 6125 27 14°
0.00V 6188 31 13°
0.00V 6313 30 11°
0.76V 5875 20 11°
0.66V 4813 0 41°
0.76V 4625 0 28°
0.16V 4656 11 18°
0.00V 4750 10 14°
0.00V 4781 9 15°
0.00V 4938 10 15°
0.00V 4906 9 16°
0.00V 5063 14 14°
0.00V 5063 17 15°
0.68V 4438 0 40°
0.64V 3719 0 42°
0.64V 3094 0 40°
0.74V 2625 0 39°
0.76V 2219 0 38°
0.76V 1938 0 37°
0.84V 1719 0 34°
0.80V 1500 0 28°
0.82V 1344 0 23°
0.82V 1219 0 19°
0.80V 1094 0 17°
0.74V 1031 0 15°
0.68V 969 0 14°
0.66V 938 0 13°

 

[keltalon]

i have the exact same problem lean at wot! i have search the boards and no answer! did you ever find out what the problem was?

 

[spyderturbo007]

Tuning with a narrowband O2 sensor is worthless. Also, the ECU does not use O2 voltage at WOT. So, although it doesn't look "pretty" in your log, it won't change your WOT tune. The only problem is your FT's are probably close to being maxed out and you are going to be burning more fuel at part throttle operation.

What boost are you running? What turbo? Did you do a leak check lately?

 

[keltalon]

Tuning with a narrowband O2 sensor is worthless. Also, the ECU does not use O2 voltage at WOT. So, although it doesn't look "pretty" in your log, it won't change your WOT tune. The only problem is your FT's are probably close to being maxed out and you are going to be burning more fuel at part throttle operation.

What boost are you running? What turbo? Did you do a leak check lately?

i agree a narrow band is worthless but my logger shows that i am lean at wot!

 

[keltalon]

fixed the problem even without the check engine light its was the 02 sensor

 

[tstkl]

since no one would help me with my o2 problems when i had them, im not going to help you....

jk,

it took me months, but i finally found the info i was looking for about my o2 sensor, maybe it can help you too

http://home.flash.net/~lorint/lorin/fuel/lambda.htm

http://www.asashop.org/autoinc/june/Tech2tech.htm

http://www.shotimes.com/SHO3badO2sensor.html

thanks to 316 stealth, the guy that has all the info in the world, and i keep forgetting that,...