Hey so I was looking over my log from the trip home and my O2 sensors are not correlating with my wideband. Some times they kinda match but a lot of times the wideband says 1.0 lambda and bank 1 will read .850 and bank 2 will read 0.145(not actual values) so I don't exactly know where to go to correct this. Attached is the latest log. Let me know if im reading too much into this. As always thank you!
also here is my MAF tune that I am using.
Where is the wideband mounted
You're in open loop, it does not matter what the o2 sensors read because they are not even being used for anything.
2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.
If you don't post your tune and logs when you have questions you aren't helping yourself.
6inches behind the narrow in bank 1Originally Posted by Ben C
I plan to return to closed loop after I finish tuning the MAF and I dont want the fuel trims to be out of wack, negating the work I am putting in. Again, unless it doesnt matter?
Whatever the o2 sensors do in open loop basically means nothing because you have forced the computer into open loop with zero o2 sensor function and zero fuel trim function.
If your wideband error is setup correctly and your end results show your error is within a few percent of zero, then your fuel trims should be very close to zero as well once your enable closed loop again.
2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.
If you don't post your tune and logs when you have questions you aren't helping yourself.
Ok so Im putting the cart before the horse. Got it! Thank you.
Also I am not sure you are aware of this but you quoted lambda value for the wideband and voltage values for the narrowbands
If the wideband says 14.7:1 and bank 1 is reading .850v and bank2 is reading .145v this is means that bank2 is leaner than 14.7 and bank1 is richer than 14.7 and the average value is showing up on the wideband
Narrowbands are extremely twitchy around 14.7 though, bank1 could be 14.6 and bank2 could be 14.8 and still get a similar result
What you DONT want to see is wideband showing 13.8:1 and bank1 is .850v and bank2 is .150v. It means bank2is still leaner than 14.7:1, they dont flip "high" (1~volt) until richer than 14.7:1
Thanks for the reply. I'm glad you picked up that I was talking lambda vs O2 millivolts. I sometimes forget to express the units of measure.
Also, I was under the impression that O2s will produce a high signal .800mV and up when rich, ~.450 at stoich, and .250mV or lower when lean because it's measuring the difference between atmosphere and the exhaust. Is this not correct?
And again the .850 and .250 are just to express the range and not an exact value.
all narrowbands are only accurate at 14.7:1 and this is around .500volts (.450volts~)
.500volts = 500mv
Once above or below that number, there is no exact number. It depends strongly on the sensor design, model, age, grounds, and temperature.
Some sensors will report .200v when others report .400v at the same a/f ratio
some sensors will report .750v when others report .995v
Some sensors can be "re-grounded" (some narrowbands i.e. 2-wire and 4-wire have redundant grounds) or even moved to cooler locations and the above reference values will change again.
The only thing that is certain is that right around .500v for a split second, 14.7 is "found". Since fuel metering is not precise enough to hold it there exactly, all computers which utilize narrowband sensors consider the narrowband as either "ON" or "OFF" as if it were a digital device. Some computers are also able to target specific mv values to enable 'lean cruise' and algorithms but this is typically unrefined from the factory and disabled until the owner decides to start collecting data and figuring out what millivolts to target given than narrowbands vary so much in this respect. Some auto manufacturers provide sensors and know this data so they might use such strategies but it is rare.
Last edited by kingtal0n; 08-20-2018 at 09:00 PM.
The narrowband sensors are a good sanity check for the widebands. As mentioned before, if the wideband reads significantly lean, the narrowband should NOT read more than 450mv. Conversely, if the wideband reads rich, the narrowband should NOT read more than 450mv. If they don't line up correctly, there is very likely, a problem with the wideband. Every time you see a transition across the 450mv line on the narrowband, you should see a corresponding transition of the wideband crossing 14.7 ( Lambda 1.00 ).\, within a few milliseconds.
I love this method and always use this to check my wideband for accuracy if there is a narrowband. I stopped using narrowbands in all my swaps though because they take up space and its another hole. But I miss having one for "backup" comparison... good tip! pro tip
Thanks for the input that set my mind at ease
What does it mean exactly to reground a o2 sensor? Im assuming one would take the ground wire from the o2 sensor and ground it on the chassis somewhere? Would this cause any pcm issues?
There are 4 kinds of narrowband I am aware of in general:
1-wire: signal
2-wire: signal, ground
3-wire: signal, heater 12v, heater ground
4-wire: signal, redundant ground, heater 12v, heater ground
I've always assumed 1-wire sensors and 3-wire sensors got their grounds from the exhaust plumbing, and the 2-wire and 4-wire sensors included an additional signal ground for correcting voltage offsets.
In the end, it usually doesn't matter if you ground them or not because the signal they generate isn't used in such a way that it matters. Which I believe is why there seem to be so many 1 and 3 wire sensors still in use.
You don't need a narrowband to run an engine. if you think you have an PCM issue the 'first thing I do' is disabled closed loop and disconnect the O2 sensors completely.
[QUOTE=dr.mike;539697]The narrowband sensors are a good sanity check for the widebands. As mentioned before, if the wideband reads significantly lean, the narrowband should NOT read more than 450mv. Conversely, if the wideband reads rich, the narrowband should NOT read more than 450mv. If they don't line up correctly, there is very likely, a problem with the wideband. Every time you see a transition across the 450mv line on the narrowband, you should see a corresponding transition of the wideband crossing 14.7 ( Lambda 1.00 ).\, within a few milliseconds.[/QUOTE
This doesnt make sense. In my logs when my wideband is rich o2 volts are high like .890mv and when lean its .040mv.....
Example- in my log when i was decelerating with dfco on my wideband read 20+afr with 02 reading .003mv. Then when in pe afr was 12.8 on wideband with 02 reading .890mv
Last edited by doorev800; 09-07-2018 at 06:43 PM.
2010 /2SS/Long Tubes/ Magnaflow axle back/LSA Conversion/ 2 bar OS running / Stock Blower Pulley...for now
He meant to say if the wideband reads rich the narrowband should (Other option (less than)) he put the same thing twice by accident
my mpg isnt what it used to b and ive only changed my pe afr tables and mulitplied them by 1 so id get that reading on my aem 30 4110 eugo controller on p0 settin it shows my actual afr while it reads rich alot when i get into the throttle but on my track addict app my 02 sensor show bank 1 sensor 1 it stays at a .63 until engine is cut off and no matter how much i accel or decel it stays the same and my rear 02 sensor jumps all the way up to .95 is what ive seen without having to put my eyes back on the road so it jump from .4 to .95 in p0 mode p1 it stays at lambda and p02 is small volt 1-2 v measure and bank 1 sensor 1 is .63 and sensor 2 is from .05-.47 p03 is the autronic emulation and it barley even moves anywere but my bank 1 sensor 1 is .63 and sensor 2 is .25 and is rises n lowers slower but p04 is also the same thing so i decided to watcj my wideband instead and log the switches and while doing all that my widwbands goes from p0 sweeping the gauge from 14.7 to 11.6 afr wot and its a steady sweep 01 doesnt move on the gauge besides from 1.00 and up or down .01 so p02 p03 p04 sweep the gauge faster and faster as im trting the switch n log it all what should i do about this to correct it or has anybody has this problem before that 276k mile Tb LS runs very good so i would like to figure it out. @doorev800 whats the wideband ur using and how about the 3rd party tuner program
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