I have been logging with Powerlogger. I have not been to the track but have made some WOT third gear runs. I have an LM-1 tied into the PL. I am getting an A/F of 10.5-10.6 thru out the pass and a steady 02 sensor number of .720. Why is this? My PL is calibrated and matches up with the LM-1 sensor. The car runs good and pulls strong. Should I just ignore the narrow band and take my tuning cues from the wideband?
A/F good...02 not so good
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GNVYUS 1
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Yes, Bruce had a great post a while back that was narrowband on one side and wideband on the other, it was obvious that the narrow band is just a reference at best.
Thanks. Do you remember the thread name?
Not being smart, but I could swear someone asked me that very same question almost a week ago. I think I told that person what they'll read in "said" thread.
FWIW my datalogs show a narrow band reading .750's and wb reading 10.2. Which one you think I'm gonna believe?
FWIW my datalogs show a narrow band reading .750's and wb reading 10.2. Which one you think I'm gonna believe?
What brand O2? How old is it? how are the grounds on the firewall? Run any leaded fuel?
I have seen cars read low o2's in the past. Sometimes its ECM, sometimes O2, sometimes grounding, etc...
See the O2 gets its ground from the header. Header connects to head/engine.. firewall ground strap ties it to the ECM grounds at that same point.
Maybe loosen the grounds at the firewall and redo them if all else fails.
Understand the difference is .03 volts... thats not a lot..
I have seen cars read low o2's in the past. Sometimes its ECM, sometimes O2, sometimes grounding, etc...
See the O2 gets its ground from the header. Header connects to head/engine.. firewall ground strap ties it to the ECM grounds at that same point.
Maybe loosen the grounds at the firewall and redo them if all else fails.
Understand the difference is .03 volts... thats not a lot..
Its a single purple wire AC 02 sensor. Maybe 100 or so miles on it. Dont get to drive my car much.:frown:
No lead fuel..just pump gas(and alky:smile: )
I have grounds all over my car.(4 guage from battery to block, frame and body) When I rebuilt the engine last year I went crazy with the grounds. I have all new ground wiring and good clean locations on all points from the head to the intake to the block etc...
I feel confident about the advice from TURBO6(he usually knows a thing or two when I pick his brain ). I just wanted to know WHY there is a discrepency in the readings and I think you may have answered my question Julio. I am not going to tear my hair out looking for a solution to a problem that is not there. My car runs great, plugs look good and there are no misses or sputters. Its just a good strong pull all the way thru the RPM range up to peak boost. No complaints other than getting rained out going to the track...
No lead fuel..just pump gas(and alky:smile: )
I have grounds all over my car.(4 guage from battery to block, frame and body) When I rebuilt the engine last year I went crazy with the grounds. I have all new ground wiring and good clean locations on all points from the head to the intake to the block etc...
I feel confident about the advice from TURBO6(he usually knows a thing or two when I pick his brain
). I just wanted to know WHY there is a discrepency in the readings and I think you may have answered my question Julio. I am not going to tear my hair out looking for a solution to a problem that is not there. My car runs great, plugs look good and there are no misses or sputters. Its just a good strong pull all the way thru the RPM range up to peak boost. No complaints other than getting rained out going to the track...Narrowband readings are useless these days imo. If you had egt numbers to compare then it would be a little better but id still ignore narrow O2 readings otherwise. The timing has a big effect on a narrowband readout too. Did you test the readings with the wideband sensor in the same spot as the narrowband? Location makes a big difference too.
My WB sensor is under the car at the end of the DP where the cat conveter would be. Im not gonna start running wire just to move the narrowband down there. I think I will just go by my WB LM-1 readings. Thanks for chiming in BISON.
As long as it's not knocking don't worry about it. Three varibles:WB,NB and knock. Two out of three wins.
I deal with control systems everyday at work. To me it's just a very simplified version of what I deal with everyday. That's the way I think I guess.
I deal with control systems everyday at work. To me it's just a very simplified version of what I deal with everyday. That's the way I think I guess.
Narrowband sensors are completely worthless for tuning air/fuel ratios other than stoichiometric, thats about 14.7:1.
They work like a three position switch, in the middle you have 14.7, and under that it will spit almost any number beneath stoich (iirc .440) , and anything above 14.7 it will spit out almost any number above the stoich MV reading for that particular sensor
this is why widebands came into existence.
Narrow bands are highly affected by temperature and pressure, to make things worse they aren't even consistent if you hold those two constant. By just varying timing, or changing your exhaust, or increasing volumetric efficiency you'll get three different WOT mV readings from a narrow band O2 sensor even though your AF ratio may have held constant.
There is even a narrowband O2 sensor "saturation point" whereby you start to run too rich, the sensor will start reading lean.
I'm still surprised that anyone doing any serious tuning looks at narrow band sensors at all for anything other than part throttle attempts at getting 128/128 blm and int. Even then, you have to run open loop so the narrow band doesn't swing which is a built in closed loop algorithm to maximize cat converter efficiency.
They work like a three position switch, in the middle you have 14.7, and under that it will spit almost any number beneath stoich (iirc .440) , and anything above 14.7 it will spit out almost any number above the stoich MV reading for that particular sensor
this is why widebands came into existence.
Narrow bands are highly affected by temperature and pressure, to make things worse they aren't even consistent if you hold those two constant. By just varying timing, or changing your exhaust, or increasing volumetric efficiency you'll get three different WOT mV readings from a narrow band O2 sensor even though your AF ratio may have held constant.
There is even a narrowband O2 sensor "saturation point" whereby you start to run too rich, the sensor will start reading lean.
I'm still surprised that anyone doing any serious tuning looks at narrow band sensors at all for anything other than part throttle attempts at getting 128/128 blm and int. Even then, you have to run open loop so the narrow band doesn't swing which is a built in closed loop algorithm to maximize cat converter efficiency.
Hey What's up man. I noticed the same thing with my nb vs. wb readings. I just thought it was amazing to see how far off they actually were. 10.6 = 720 ish with mine too! I'm just tuning off the WB thats what I got it for. P.S. I still love that PTC!! I'm gonna run it over the weekend so I will get you some new times! Jason
