O/2 sensor location,where is the sweet spot???????

I'm getting some silly readings from the O/2 sensor,the log looks more like a seismograph.I have the sensor about 8 inches from the header pipe merge in the bend inward toward the "X" .
Monte said it's most likely in a turbulent location.The sensor is at the 9 o'clock position.

SO where IS the sweet spot to install the sensor???

I put them in a straight run area.. about 6"
after the end of the primaries.. if yu were
running open headers I want 8"-10" before the
end of the collector.. that way it wont back
flow and pick up out side air which could give
you bogus readings on shut down or a steady rpm..
make sure the sensor is pointed a little downward
(on the inside) the drop off moisture when its
cooling... try not to put it near the X.. being that
just pulses back and forth

I have put sensors all over primary pipe, collector, before the merge, after and 8 inches down stream. I have never had a problem with reading jumping around. With that being said if there is high pressure hitting the O2 sensor the reading will change. On the dyno, when we do a turbo engine, I have a pressure sensor in the exhaust manifold that allows for a correction factor to be used.

this is from the Daytona sensor site, they have a chart that show the pressure relationship



http://www.daytona-sensors.com/tech_wego.html

hope this helps


joe

I would put your exhaust cutouts in before I moved the 02s, that back pressure could be causing the crazy readings.

Mine is mounted in the header collectors 2-3" upstream from the attachment flanges. This location has worked well for me... also what TTI recommended when they made the headers.

The sensor is junk. You could put it on the moon and it would still read lean.
Buy a new sensor, do a clean air calibration. Don't run the engine with ratios lower than 12.0:1.
Read the manufacturers mounting recommendation. Mount it in a position that is least likely to get any liquid on it.

has someone been using leaded fuel. & KILLED the o2 sensor ?

NO





That was the last set,,,,,,,,,,

Put a new set on before parking it for the winter.

What's the difference between pressure & back pressure in the 4 inch pipe??

Shopping for pipe & v bands to fab cut outs

Could be a wiring problem - loose / bad ground can do that.

MMMMMMM

Bit confused by this, with no volts the O2 sensor (mine) will read 10.4 AFR and with full voltage (5 volts) it will read 19.5. So if it is a loose ground, I would expect a rich reading followed by a lean spike when it reconnected (maybe?).

Joe

A new "set"?
Do you have 2 sensors?
Did you get the same results with the new sensor(s)?
I assume the wb control box has a +5v out. Are you also using a shared SIGNAL ground?

Have not been out yet with the new pair of Bosch sensors.
Not sure on the shared signal ground,,,,,,,,,,

You might be in the same boat,,,,,,,,,,,

Really just shooting in the dark here. I cant tell scale/ value without a ref point.
You say you have 2 sensors. I see the other sensor is showing close to the same value at the cursor time line. As a trend, are they both reading the same values? If so, I guess my bad sensor theory is out the window.
Are your sensor outputs calibrated correctly to your logger?
Many WB controllers have configurable outputs. I usually set the low voltage(rich) to .5 volts 10:1 a/f ratio. Then set my high voltage(lean) to 4.5 volts 20:1 a/f ratio.
This gives wiggle room when setting the logger/ecu input values.
There are very few instances when I see NO offset voltage between output and input readings on two separate devices.
I check the offset amount by setting the wideband controller to send out a straight line voltage, regardless of a/f ratio.
As an example...
10:1 a/f = .5 volts
20:1 a/f = .5 volts
Now your wideband should be outputting .5 volts no matter what the ratio is. Check your datalog. If the voltage doesn't read .5 volts, you need to mathematically change either the output voltage, or the read value.
Do the same with the high voltage...
10:1 a/f = 4.5 volts
20:1 a/f = 4.5 volts
Same deal. I keep that .5 volt window on the high and low side for offset changes. If you don't need the "windows" on the high or low side, you can widen the voltage swings(.2 volts-4.8 volts) to get better resolution.
The reason I asked about sensor ground commonality, is there are frequently these ground offsets. Some manufaturers dont want other devices to share, and some do.

At his point,I must verify the grounds for the o/2s and see it the new sensors give a better readout.I figure 2s or 3 passes to verify where I left off last.Then open the cut outs and see what happens.
Took a few more pics and must figure out how I want to fab the cutouts.

Listen to what Trendz wrote. Others have mentioned there is no way the car can run at 19:1 a/f under load, and both sensors are reading lean. There is likely a wiring problem, and you can start by checking the voltage being read at your data acquisition unit.

Grounds are critical to these sensors telling you the truth.

All ground locations are not created equal so if the mfg instructions say ground to a specific location, just do it. If the ground potential for the controller is different than the sensor you get a ground differential and a false reading.

Just to verify, zero leaks upstream of the sensor ie header flange gaskets and no pan evac?

Kevin

This is great Info I am having the same problem woth my fast xfi system and mostly at idle.

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Here is an interesting check of the O2...
http://www.yellowbullet.com/forum/showthread.php?t=1275090

You shouldn't put too much stock in AFR readings at idle, especially with a lumpy cam. You set it so the engine is happy and the AFR is what it is.

With a cam with a lot of overlap you get a lot of random misfires or half fires at idle and all the oxygen that doesn't get used parades past the O2 sensor and you get a lean reading when in fact it could be/likely is pig rich.

Kevin

Somewhat related. Anyone using WRO2 in conjunction with crankcase evac?

How close can the evac lines get to the sensor before it may effect readings?

i know you need to have the o2 sensor up stream from the evac.

10 or 2 o clock
No leaks up stream

Yep thats the recommended . i had mine at 9 oclock.

on a straight pipe 9/3, never on the inside of a curve section..

A couple of inches is plenty as long as the O2
is up stream.. I have been a little closer without
any issue.. big overlap cams pulse a lot at idle

It's downstream, but I was worried about pulses. I got it sorted last night. Getting close to firing the EFI up if it would stop snowing...