Best Wideband O2 Sensor Location?

[2000StreetRod]

I just received an AutoMeter 5978 Wideband Air/Fuel Ratio Monitor kit. The instructions say to install the sensor "as close to the cylinder head as is reasonably possible. . . . For cast iron manifolds install the sensor in the pipe just below the manifold. . ."

My 2000 SOHC V6 has the stock manifolds and I don't plan to ever replace them. There are two stock catalytic converters with O2 sensors installed before and after each one.

For those of you who have a wideband A/F monitor, where is your sensor located? In your opinion, where is the best location?

 

[IZwack]

Just anywhere upstream of the cat really. But the problem is that you're only able to read the O2 data from one bank - in other words, you only get data from 3 of the 6 cylinders.

 

[Carguy3J]

I just received an AutoMeter 5978 Wideband Air/Fuel Ratio Monitor kit. The instructions say to install the sensor "as close to the cylinder head as is reasonably possible. . . . For cast iron manifolds install the sensor in the pipe just below the manifold. . ."

My 2000 SOHC V6 has the stock manifolds and I don't plan to ever replace them. There are two stock catalytic converters with O2 sensors installed before and after each one.

For those of you who have a wideband A/F monitor, where is your sensor located? In your opinion, where is the best location?

I have mine in the left (driver) side exhaust pipe, right after the stock upstream O2.It really needs to be before the CAT to be accurate. This location made it very easy to route all the wires through my center console, under the carpet, and right out of a stock drain plug on the floor, almost right under the driver seat. Jusr remember to watch your "clocking" on the sensor. Keep it between 9 and 3, to prevent the sensor from being exposed to collected condensation.6 o'clock (pointed straight down) is to be avoided at all costs. Also,remember, very important:
1.) If the sensor is installed in the pipe, it MUST be powered through the controller/display any time the engine is running. An unpowered wideband sensor is very quickly ruined by running the engine w/ an unpowered sensor. The only exception is :
2.) In order to avoid cracking the sensor from heat shock, from cold condesation blowing on a heated sensor; Start the engine first, wait about 10-20sec, then turn in the wideband/sensor. This give the engine a chance to blow out any water that collected in the pipe while sitting.

You might want to also weld a bung on the right side pipe, in a similar location, and put a pipe plug in it for now. This way, you can occassionaly switch the sensor to the other bank, to see if there is any difference in A/F bank-to-bank, which there very well could be. I would bet that someone willing to spend the time to tune each bank seperately would find some hidden HP and fuel economy.

 

[2000StreetRod]

Thanks CarGuy3J!

Your information was very informative and helpful! I may mimic your installation.

 

[2000StreetRod]

Only choice

I have mine in the left (driver) side exhaust pipe, right after the stock upstream O2.It really needs to be before the CAT to be accurate. . . Just remember to watch your "clocking" on the sensor. Keep it between 9 and 3, to prevent the sensor from being exposed to collected condensation.6 o'clock (pointed straight down) is to be avoided at all costs. . .

After crawling under the vehicle searching for possible locations it appears that the only choice is the one that you selected. The oil filter (or in my case the remote oil filter block adapter) essentially eliminates the passenger side. I'll get mine positioned on the driver side in a spot where it won't be in line with either of the header to downpipe bolts. I don't have the longer center console like the 4 door Explorers. I may just cut a hole in the floor under the carpet just large enough to pass thru the instrument connector and then install a grommet to plug the hole.

 

[2000StreetRod]

Confirmed your choice

I have mine in the left (driver) side exhaust pipe, right after the stock upstream O2.It really needs to be before the CAT to be accurate. This location made it very easy to route all the wires through my center console, under the carpet, and right out of a stock drain plug on the floor, almost right under the driver seat. . . Also,remember, very important:
1.) If the sensor is installed in the pipe, it MUST be powered through the controller/display any time the engine is running. An unpowered wideband sensor is very quickly ruined by running the engine w/ an unpowered sensor. The only exception is :
2.) In order to avoid cracking the sensor from heat shock, from cold condesation blowing on a heated sensor; Start the engine first, wait about 10-20sec, then turn in the wideband/sensor. This give the engine a chance to blow out any water that collected in the pipe while sitting. . .

After checking further I found that in order to get above the stock O2 sensor I would have to remove its heat shield and there probably wouldn't be enough room to even weld the bung. See photo below.

I will have my new bung inserted in the same location as yours - just downstream of the stock sensor. However, if the threads are the same, I will replace the stock sensor with the wideband sensor. I'll screw the stock sensor into the newly inserted bung. The wiring will be routed above the downpipe and thru the grommet that the speedometer cable passes thru. You can see the wiring harness is covered with heat shield sheathing in the vicinity of the downpipe.

The AutoMeter A/F meter has no user Off/On switching capability. The meter automatically starts heating the wideband O2 sensor when the ignition voltage exceeds 13.5 volts. My ignition voltage is normally 12.6 volts when the engine is not running so the heater will not be activated until the engine is started and a 20 second count down begins. After 20 seconds it is assumed the sensor is warm and accurate and the meter displays the AFR/lambda.

 

[2000StreetRod]

Sensor installed

I finally finished my remote oil filters and coolers installation http://www.explorerforum.com/forums/showthread.php?t=247990 and was able to drive to a local exhaust shop to have my wideband O2 sensor installed as shown below.

As planned I had the technician remove the stock sensor and screw it into the newly installed bung downstream. Then he installed the wideband sensor in the stock bung closer to the exhaust manifold. Both sensors were installed with antisieze compound applied to facilitate future removal.
The photo below shows the functional A/F meter.

I was surprised at how quickly after starting the engine that the A/F ratio increased from around 11.0:1 to 14.7:1. It was also interesting to notice the meter max out when letting off the gas and coasting in gear.

I'll drive for a while in this configuration until I become familiar with the stock A/F ratio characteristics. Then I'll install my replacement intake system using a Lightning 90mm MAF sensor and my MAF sensor amplifier (MAFSAmp) http://www.explorerforum.com/forums/showthread.php?t=249266 and compare the results. I anticipate the PCM generating some DTCs when I adjust the mixture to 20% rich and 20% lean when driving even though none were observed when the engine was revved to 5500 rpm while in Park.

 

[CDW6212R]

Good work, I need to add a bung like that in mine also.

 

[2000StreetRod]

ethanol added fuels

In preparation for another custom tune using E10 fuel I experimented with the data logger output capabilities of my air/fuel ratio meter. Even though I can set the display mode for lambda instead of a specific stoichiometric air/fuel ratio the data logger output is always relative to the selected stoichiometric ratio (default is 14.7:1 for unleaded gasoline). The data logger output range is 0 to 4 volts. I can set 0 volts to correspond to any lower ratio limit (default is 10:1 for unleaded gasoline) and 4 volts to correspond to the upper ratio limit (default is 16:1 for unleaded gasoline). With E10 fuel the ethanol content can be up to 10% and can vary with each fill up. In order to achieve an accurate desired lambda for the tune using a datalog I will have to determine the stoichiometric air/fuel ratio of the fuel in the tank. The formula is stoic AFR = (14.7*%gas)+(9.0*%ethanol). For example the stoic AFR for 10% ethanol = (14.7*.9)+(9.0*.1) = 14.13. When lambda on the display reads 0.86 (max power) I can switch to AFR and record the value and use that for the target WOT AFR on the datalog. Or I should be able to read the AFR when the displayed lambda is 1.00 and record that. From it I should be able to compute the target WOT AFR.