Wideband sensor
Team Owner
Joined: May 2004
Posts: 26,345
Likes: 231
From: SoCal
Originally Posted by Billdog350
Some O2's are double duty. I can calibrate my LC-1 auxiliary output to match a narrowband (0 to 1 volt) signal to the PCM. You can change the drop off rate and sensitivity so it looks exactly like a narrowband to the ECU.
You have a wideband sensor in one of the existing sensor positions. Then you calibrate that sensor to act as a narrow band during normal use and a wideband during tuning ????
And if this is correct....do you have it in front or back. Seems that even when you are tuning you need the front sensor providing normal narrow band feed back to the PCM.
Thanks
DH
Drifting
Joined: Dec 2005
Posts: 1,720
Likes: 3
From: East Hampton CT
Originally Posted by Dirty Howie
So if I understand you correctly......
You have a wideband sensor in one of the existing sensor positions. Then you calibrate that sensor to act as a narrow band during normal use and a wideband during tuning ????
And if this is correct....do you have it in front or back. Seems that even when you are tuning you need the front sensor providing normal narrow band feed back to the PCM.
Thanks
DH
You have a wideband sensor in one of the existing sensor positions. Then you calibrate that sensor to act as a narrow band during normal use and a wideband during tuning ????
And if this is correct....do you have it in front or back. Seems that even when you are tuning you need the front sensor providing normal narrow band feed back to the PCM.
Thanks
DH
Le Mans Master
Joined: Dec 2003
Posts: 5,561
Likes: 448
From: Atlanta metro Ga.
Optimum location for any W/B sensor is before the cat converters, in a location similar to Mike Mercury's post.
Most tuners claim approximately 2 tenths (lean) difference between before and after the cats.
Most tuners claim approximately 2 tenths (lean) difference between before and after the cats.
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
Originally Posted by see5
Using rear bung or tailpipe is not more than a few tenths difference.
May not be a problem if you have the effeciency rating of that cars particular converter.
But then it becomes a problem because the efficiency of a catalytic converter changes over time. So, to do an accurate variance calculation of the amount a converter alters an AFR reading - would be calculated by:
a). The efficiency of that particular cat.
b) then further skewed by the mileage of the car.
Does such data exist ????
Who drops their car off at a tuner, pays $350 to $600, and then says "do your best guessing" ???
Cats do not remove O2.
I thought you said "not more than a few tenths difference".
Originally Posted by Billdog350
This is exactly what I said and people jumped all over me.
Furthermore there are TONS of legit tuner shops who shove a sensor in your tailpipe regardless if you have cats.
.
Safety Car
Joined: Jan 2001
Posts: 3,879
Likes: 3
From: Hobart, WI
Originally Posted by Mike Mercury
but it's not a constant; and that's where the problem is. The amount of variance depends on the efficiency of the cat.
May not be a problem if you have the effeciency rating of that cars particular converter.
But then it becomes a problem because the efficiency of a catalytic converter changes over time. So, to do an accurate variance calculation of the amount a converter alters an AFR reading - would be calculated by:
a). The efficiency of that particular cat.
b) then further skewed by the mileage of the car.
Does such data exist ????
Who drops their car off at a tuner, pays $350 to $600, and then says "do your best guessing" ???
I thought you said "not more than a few tenths difference".
no one "jumped" all over you... you said "supposedly before cat, after cat, and tailpipe will all read similarly"; and that needed to be corrected.
OK then; name just 5 , so we can determine for ourselves whether they are "legit" or not.
.
May not be a problem if you have the effeciency rating of that cars particular converter.
But then it becomes a problem because the efficiency of a catalytic converter changes over time. So, to do an accurate variance calculation of the amount a converter alters an AFR reading - would be calculated by:
a). The efficiency of that particular cat.
b) then further skewed by the mileage of the car.
Does such data exist ????
Who drops their car off at a tuner, pays $350 to $600, and then says "do your best guessing" ???
I thought you said "not more than a few tenths difference".no one "jumped" all over you... you said "supposedly before cat, after cat, and tailpipe will all read similarly"; and that needed to be corrected.
OK then; name just 5 , so we can determine for ourselves whether they are "legit" or not.
.
The repeatability of a 02 sensor is not 100%, narrow or wideband, let alone between two different sensors. I have dynoed many times with no cats my PLX in the header and dyno shops Bosch (same) in one tailpipe. Do they read together- no. Close, but about the same as with cats. Do cats degrade, sure but it does not seem to bear on the 02 content.
I have only used 3 different dynos and they all use tailpipe sensors by default. What is a tuner to do, there are not many folks around with welded precat bungs.
Most of us who self tune have bungs welded in because we are relatively hard core, but I have no qualms about using after cat bungs because it proves out every time. Maybe a tenth or two but that is within normal variance.
Just my experience---
Drifting
Joined: Dec 2005
Posts: 1,720
Likes: 3
From: East Hampton CT
I said similarly, not "exactly the same"...whatever, we're getting into symantecs now.
Regardless, in a N/A application you're not going to melt down your motor with a few tenths difference. If you're not getting knock and you're at 12.8:1..even if its really 13:1 you're ok....Most NA LS1's that I've seen don't care a few tenths either way for hp...I mean 12.6 vs 12.9 and you're within 2-5hp....that's not much of a difference. If you're looking for the "optimal" location of the sensor, closer to the collector will be your best bet on a header car....but anywhere in the exhaust system will get you in a safe tune that puts out good hp.
My "street" tune on my LC-1 was dead nuts matching the sensor at the dyno when I tested it a few days later.
Regardless, in a N/A application you're not going to melt down your motor with a few tenths difference. If you're not getting knock and you're at 12.8:1..even if its really 13:1 you're ok....Most NA LS1's that I've seen don't care a few tenths either way for hp...I mean 12.6 vs 12.9 and you're within 2-5hp....that's not much of a difference. If you're looking for the "optimal" location of the sensor, closer to the collector will be your best bet on a header car....but anywhere in the exhaust system will get you in a safe tune that puts out good hp.
My "street" tune on my LC-1 was dead nuts matching the sensor at the dyno when I tested it a few days later.
Melting Slicks
Joined: Mar 2005
Posts: 2,252
Likes: 181
From: NE OH
2 comments:
1) Most wideband systems have a method for simulating the narrow band signal. Therefore you can run a WB in place of an existing NB sensor. Downside to this is if, you have issues with the WB, most likely you'll have NB issues also, which will affect how the car runs in CL mode.
2) Most (every??) dyno's use WB sensors in the tail pipe. These units are not calibrated to each individual 'cat' efficiency. Therefore I'd would suggest that the difference in O2 readings is not significant between pre and post cat readings.
1) Most wideband systems have a method for simulating the narrow band signal. Therefore you can run a WB in place of an existing NB sensor. Downside to this is if, you have issues with the WB, most likely you'll have NB issues also, which will affect how the car runs in CL mode.
2) Most (every??) dyno's use WB sensors in the tail pipe. These units are not calibrated to each individual 'cat' efficiency. Therefore I'd would suggest that the difference in O2 readings is not significant between pre and post cat readings.
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