checking wideband accuracy with the narrowband?

[ryans1000]

I'd imaging you can check wideband accuracy with the narrowband around stoich?

Anybody have a log with wideband with narrowband o2 pid's. I'd like to look at it? I have one narrowband o2 sensor that just stays .4 volts most of the time and I'm pretty sure thats bad and my other o2 sensor doesn't seem to follow the wideband correctly.

This graph would represent the ls1 narrowband voltage table correct?

http://www.plxdevices.com/products/wideband/NarrowbandOutputGraph.jpg

[joecar]

With COS5 I set B3647 to give semi-open loop (which uses STFT to trim to stoich)...

Look at how AFR_WBOS1 oscillates tightly around AFR...

http://img32.imageshack.us/img32/3746/solr.png

HO2S11 = OEM NBO2 signal, HO2S21 = LC-1 NBO2 signal.

[5.7ute]

Narrowband voltage is more like the pic I have attached, & is effected by the exhaust temp.

[joecar]

Here's the log... I searched thru a whole pile of old log files to find it...

This was with FSV1 and LC-1... :cucumber::banana:

[joecar]

My LC-1 is providing the NBO2 "equivalent" signal.

[ryans1000]

Narrowband voltage is more like the pic I have attached, & is effected by the exhaust temp.

Thats quite a vertical line there by stoich!

Joe, thanks for the info. On that last log you posted, even though you named the file OLSD_xxxx you are also doing closed loop or partial closed loop in that log too correct? Sure looks like it. I added the pid calc.afr.lc11 to your log and seems like that isn't right, seems to oscillate too lean compared to the narrowbands. Is that the right pid to view your wideband afr?

Sorry I'm new to this.

[joecar]

Yes, Semi Open Loop (i.e. any cell in B3647 set to EQ 1.00).

[5.7ute]

Thats quite a vertical line there by stoich!



Yep. Thats why we have B4105/B4107.

[swingtan]

I had a look at trying use the NB like a WB, by setting up a lookup table with averaged NB voltages. What I found was that the NB never really read the same voltages for the same given conditions over time. I doubt very much that you could use them to check anything other than an averaged "switch point". This is about the only thing the NB does well, switch from higher to lower voltages. The actual voltage levels themselves mean very little when taken on their own.

I guess the closest you could do is to is to average a very large amount of NB data to tell if the WB is in the same ball park reading. But I think that that's as close as you would get. The idea of any of the graphs giving a true indication of voltage vs AFR, would be a "general response" curve and not based on actual calibrated data. All the NB has to do is switch quickly to indicate a rich or lean condition, and provide an average of about 450mV via the switching. This will then allow the ECM to correct the average mixtures to the correct ratios.

Simon.

[joecar]

...
I added the pid calc.afr.lc11 to your log and seems like that isn't right, seems to oscillate too lean compared to the narrowbands. Is that the right pid to view your wideband afr?
...I had programmed my LC-1 to give AFR = V + 11, which is CALC.AFR_WB_A1 in the calc_pids.txt I attached.

[joecar]

Exactly what 5.7ute and swingtan said, the NB's transfer function is too steep to be used as an indicator of AFR, even at stoichiometry... the best you can do is see that the voltage switches which indicates that the PCM is driving/trimming on either side of stoichiometry.

Whenever the NB voltage is static at around 450mV, this indicates that there is some problem.

[ryans1000]

I had programmed my LC-1 to give AFR = V + 11, which is CALC.AFR_WB_A1 in the calc_pids.txt I attached.

Ohh I see. I missed see the pid file you attached . Makes sense now.