Wideband O2 behavior
Thread Starter
Intermediate
Joined: Nov 2007
Posts: 27
Likes: 0
From: Morton IL
Wideband O2 behavior
Hi - On my wideband O2 meter (Innovate LM2) the numbers constantly fluctuate between about 14.6 and 15.2 at cruise (2000 rpm). Is this normal? Just wondering if the narrowband O2 sensors are working correctly (95 LT1 - original as far as I know) - the O2 sensors original - the engine fresh rebuild to a 383. ported heads, mild cam, stock exhaust.
Thanks
Dan
Thanks
Dan
Last edited by dfarney; Feb 27, 2010 at 01:32 PM. Reason: to clarify what was "original"
Race Director
Joined: Sep 2001
Posts: 14,685
Likes: 753
From: NEwhere Ohio
yes.
Now my question is my numbers fluctuate between 14.6 and 15.8 - with occasional spikes to 16.2 at cruise. Is that normal? Im assuming its better to be lean than rich at cruise.
However, unfortunately my car's MPG isnt anything special.
If you interested in other peoples wideband o2 operation, check youtube.
Now my question is my numbers fluctuate between 14.6 and 15.8 - with occasional spikes to 16.2 at cruise. Is that normal? Im assuming its better to be lean than rich at cruise.
However, unfortunately my car's MPG isnt anything special.
If you interested in other peoples wideband o2 operation, check youtube.
Thread Starter
Intermediate
Joined: Nov 2007
Posts: 27
Likes: 0
From: Morton IL
O2 mV fluctuate also
Here are some O2 mV readings from a Datamaster log. TPS% - 2.7, Speed - 36, Spark Advance - Mostly 34.0 (varied from 33.0 to 36.0), Spark retard - .2 (one record .3), Knock count did not change, 19 consecutive records from 6416 to 6434 (just so that I can find this spot again)
626 768
151 773
49 755
102 764
706 462
795 293
795 284
786 524
453 710
71 107
49 151
102 688
706 728
750 519
702 178
768 129
342 346
426 750
670 724
Is this normal? I assume that these fluctuations are what are causing the wideband O2 values to change also. Is it just that my tune is not dialed in yet?
I'm learning a lot and appreciate any and all help
Dan
626 768
151 773
49 755
102 764
706 462
795 293
795 284
786 524
453 710
71 107
49 151
102 688
706 728
750 519
702 178
768 129
342 346
426 750
670 724
Is this normal? I assume that these fluctuations are what are causing the wideband O2 values to change also. Is it just that my tune is not dialed in yet?
I'm learning a lot and appreciate any and all help
Dan
Drifting
Joined: Jun 2001
Posts: 1,704
Likes: 459
From: Mass Mass
In order for the Catalytic Converter to “Light Off” and continue to maintain a working temperature, it actually needs some excess fuel (rich fuel mixture) in the exhaust.
Most OEM’s will cycle from Rich to Lean (but averaging 14.7) during normal driving to provide the fuel “wash” to keep the converter happy.
See the image bellow.
That’s why the cheap AF meters, using the narrow band sensors output, bounce around and are worthless during normal cruising.
With a Wide Band AF meter, your results will depend on how the data sampling matches the OEM software’s cycle, and how much filtering (averaging) of the data is being done.
You can imagine if you read mostly on the Peaks or Valleys, how your readings could be skewed.
Most of the Wide Band meters should have settings to increase averaging or change the sample rate, which should help your problems.
Most OEM’s will cycle from Rich to Lean (but averaging 14.7) during normal driving to provide the fuel “wash” to keep the converter happy.
See the image bellow.
That’s why the cheap AF meters, using the narrow band sensors output, bounce around and are worthless during normal cruising.
With a Wide Band AF meter, your results will depend on how the data sampling matches the OEM software’s cycle, and how much filtering (averaging) of the data is being done.
You can imagine if you read mostly on the Peaks or Valleys, how your readings could be skewed.
Most of the Wide Band meters should have settings to increase averaging or change the sample rate, which should help your problems.
Safety Car
Joined: May 2002
Posts: 4,659
Likes: 82
From: Toronto ontario
It all depends on the sample rate. if the sample rate is very High then it will pick up all kinds of odd mixes especially the spikes when you are on/off throttle. take an average over a period of time at say a steady cruise and throttle position and see if it remains fairly constant. 
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Thread Starter
Intermediate
Joined: Nov 2007
Posts: 27
Likes: 0
From: Morton IL
It all depends on the sample rate. if the sample rate is very High then it will pick up all kinds of odd mixes especially the spikes when you are on/off throttle. take an average over a period of time at say a steady cruise and throttle position and see if it remains fairly constant.
My main concern at this point is are the NB O2 sensors working correctly?
The datamaster log was taken at stock settings - 9 or 10 records per second - not sure if I have that right. Would it help if I posted the log here?
Actually I would welcome someone looking at it as I am also working on reducing some spark retard and knock counts at certain conditions.
Thanks
Dan
Pro
Joined: Jul 2002
Posts: 703
Likes: 0
From: Milwaukee Wi
Innovate has a smoothing function in data logs so it will show less erratic. If you install a DB gauge on pillar you also can set it up to average it out. My DB shows an updated A/F about once every second. It will show like 15.0-14.9-15.0-15.1 every second a new value appears.
