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  #1  
Old 08-22-2020, 07:18 PM
Vans101 Vans101 is offline
 
Join Date: Apr 2016
Location: San Jose
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Default Are Wide Band O2 Sensors Affected By 100LL

I am interested in installing a wide band O2 sensor to read air fuel ratio. If I run 100 LL will the lead foul the sensor?
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  #2  
Old 08-22-2020, 08:41 PM
rocketman1988 rocketman1988 is offline
 
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Default yep

Yes, I am not flying yet but a friend had to replace his after about 40 hours...
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  #3  
Old 08-22-2020, 08:51 PM
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rv6ejguy rv6ejguy is offline
 
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Default

Life of the sensor is 1-10% when operating on 100LL vs. unleaded fuel.
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  #4  
Old 08-23-2020, 08:26 AM
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riseric riseric is offline
 
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Default

I just received one from PLX Devices to complete the (not running yet) EFII System 32 installation.
Not installed, and had not considered the 100LL v.s. unleaded fuel aspect.


If as Ross says its life would be 10%, I will reconsider drilling a hole in the beautiful Trombone Vetterman exhaust...


BTW, PLX Devices mentions to install the O2 sensor at least 2 feet from the cylinder head. I presume to prevent exessive heat.That would mean after the muffler in the (short) end tail pipe.

Does anyone know how that would affect its readings, IF I choose to install??
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  #5  
Old 08-23-2020, 08:49 AM
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rocketbob rocketbob is offline
 
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Quote:
Originally Posted by rv6ejguy View Post
Life of the sensor is 1-10% when operating on 100LL vs. unleaded fuel.
I thought these things lived longer if they were kept out of the exhaust flow thru the pipe if the welded bung was tall enough...?
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  #6  
Old 08-23-2020, 08:57 AM
622BH 622BH is offline
 
Join Date: Nov 2011
Location: Albany, OR
Posts: 170
Default According to Theory...

Lead deposits are most likely when "cool" temps are permitted in the cylinders (and exhaust in the case of the O2 sensor). Robert at EFII recommends placing the sensor bung up close to the flame-front as it comes out the exhaust valve, thus keeping the temperatures up and the formation of lead deposits down. Though I cannot verify by personal experience, he says the sensor should last a very long time in that environment.
My sensor is down the pipe a bit and failed after about 50 hours. With the new system 32 installation, I am thinking of moving the bung up as Robert suggested and see how that works.
Needless to say, once you weld the bung in place, the mounting flanges will never come off the pipe... OR, put another way... you had better make sure the mounting flange is in place before you weld the bung - you'll not get it on if you don't!
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  #7  
Old 08-23-2020, 09:33 AM
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rv6ejguy rv6ejguy is offline
 
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We've seen the Bosch 4.9 LSU sensors last as little as 2 hours and as long as 300 using 100LL. Location doesn't seem to make much difference. There is some evidence that a long boss holding just the very tip (.100) into the exhaust stream may extend life slightly. Normal lifespan in auto use is 2500-4000 hours.

The biggest concerns are thermal shock, powering the sensor heater up at the same time as engine start (the auto OEMs don't do this) and condensation hitting the sensor on warmup (hence cautions about orientation in the pipe to help mitigate this).

Also, be sure to have the sensor mounted at least 12 inches from atmosphere to avoid dilution during valve overlap and reversion in the pipe.
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  #8  
Old 08-23-2020, 02:16 PM
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JoopSJ JoopSJ is offline
 
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According to Robert Paisley installing it much closer to the cylinder will keep the lead deposit off the sensor:
https://vansairforce.com/community/s...=173975&page=2
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  #9  
Old 08-23-2020, 02:38 PM
lr172 lr172 is offline
 
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Quote:
Originally Posted by JoopSJ View Post
According to Robert Paisley installing it much closer to the cylinder will keep the lead deposit off the sensor:
https://vansairforce.com/community/s...=173975&page=2
That assumes that lead deposits are what kill them. Also possible that the lead present in the exh before it's deposit onto something is damaging when it comes into contact with the precious metal inside the senor. I know little about this, but know enough to be suspicious of a theory to only relies on deposits as the cause. Many of these metallic elements have unique reactions with gaseous elements. Just consider how a catalytic convertor performs it's function. Wouldn't be surprised that the opposite occurs as well. That certain gaseous elements change the make up of the precious metal.

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Last edited by lr172 : 08-23-2020 at 02:43 PM.
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  #10  
Old 08-23-2020, 03:19 PM
219PB 219PB is offline
 
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Default

My first sensor lasted about 10 hours on my EFII system. I was running the engine rich for break-in. I now run aggressive lean of peak and the aircraft has a 100 hours on the replacement sensor.
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