SBNova

I know this magazine isnt that well known, but has anyone seen the Oct/04 issue? They have an article on WBO2's, and they made a test pipe, with five bungs. They ran four wide bands- PLX,"DIY-WB", Performance trends, and FJO. Two had NTK's, Two had Bosch. They ran one narrow band, and compared.

They said "We felt here wasnt enough variance between the controllers to say any one was more accurate than any other" and they said a few interesting things about the narrow band backing the findings in this forum;
" "we also found that when the narrow band sensor did show some variance, it was not repeatable. The narrow band would show different volt readings on different pulls, all while the wide band units showed a constant air/fuel ratio of 13:1 fro each run"

"in fact, we found narrow band voltages varying from .579 to .964 volts- in theory corresponding to a/f ratios ranging from approximately 10.6:1 to 14.6-1- when the wide band units were consistently saying 13:1. This variance and lack of repeatablilty certainly shows that the narrow band unit is flawed as a tuning device."

This definately seems to back the recent posts on this topic lately, and maybe shows why 128 BLMs does not always = 14.7:1.

I thought everyone might be interested in those results from a real (magazine article)test.

ben73

That sounds like an interesting article to read! Good info, backs what we always thought ;-)

RednGold86Z

iTrader: (1)

Narrow band is still fine for finding 14.7, since in fact it never finds 14.7 and stays there, it just shoots past it and when the sensor responds, it takes a jump backwards and shoots back the other way. As long as the overshoot is less than 3%, and overshoot is consistant both ways, and response is similar low to high and high to low, you can say it's 14.7 average. That's what the cat likes, and that's what the sensor switches at. From that 14.7 you can add % fuel based on what was learned as 14.7 to achieve other A/F's, but, as the article shows, you can't use the actual voltage to tune.

Low C1500

The NB sensor reading fron 580 to 950 mv, is total crap. The sensor is either a crappy brand, or it was somewhat faulty. I make wot tuns all the time, my sensor shows 880 mv, +/- 20 mv, all the time.

Cobra289

It doesn’t say that the sensor only measure .579 to .964 mv it say that when measure .579 to .964 mv it correspond with 10.6:1 to 14.6-1 AFR.
Regards,
Cobra289

Low C1500

I am aware of the NB voltage conversions to AFR. I understood the first post to mean that the sensor was unconsistant in its wot readings from one run to the next.

onebinky

iTrader: (1)

That's what a narrowband is supposed to do, it's just the x-counts. If you average the 2 numbers together you get 12.6:1. Still not completely accurate, but as it was mentioned NB o2 is only accurate at stoich.

Unless those readings were stable, and on different runs completely. Then ignore what I said