O2 extender CEL Eliminators
Thread Starter
Racer
Joined: Jul 2013
Posts: 351
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From: New York
O2 extender CEL Eliminators
Hello, I wanted to ask about my 2007 Suburban and thought I might find the best answer here. It is used off road and has no cats. I have the rear O2 sensors in stock location and don't want to look at a check engine light from codes 420 and 430. I first tried some cheap Chinese O2 sensor extenders with a perforated cap with just some kind of material in it. They actually worked for over a month but then threw a code. When I removed them, the perforated cap had unscrewed itself and all the material was gone. I almost think the material probably did nothing but the perforations in the cap restricted the exhaust enough to make them work. I then tried mini cat O2 extenders which threw a code after a week. I assume they didn't work or I burned out the catalytic material right away. They had no orifice or perforated cap so the full diameter of the opening allowed a lot of exhaust gas to flow to the O2 sensor.
I think the key to these working is correct sized orifice so the gas flow to the O2 sensor is just enough to keep it's voltage as constant as possible.
So doesn't anyone have any experience with this? Do you know the sweet spot for the orifice size? Why wouldn't no orifice at all work to just keep the O2 sensor's voltage completely constant by it seeing no exhaust gas at all?
Thanks
I think the key to these working is correct sized orifice so the gas flow to the O2 sensor is just enough to keep it's voltage as constant as possible.
So doesn't anyone have any experience with this? Do you know the sweet spot for the orifice size? Why wouldn't no orifice at all work to just keep the O2 sensor's voltage completely constant by it seeing no exhaust gas at all?
Thanks
Race Director
Joined: Dec 2013
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The rear o2 sensor are just there to make sure that the cats are working, nothing else. So without cats and the sensors in play, they have to be pulled far enough out of the stream that they are really not taking a full reading instead.
So your looking for something like the below, so the sensors only get a light whiff of exhaust, so they read low, like they would be in the stream after cats instead.
Short of this, then just use HP turner to turn off the SES code reading instead.
Again, rear sensor only see if the cats are reducing, and nothing more. Hence don't need the sensors in play, since they do nothing with the tune values when the the car is in either open or closed loop. So normal for the front sensor to peak up to 9V and down to 2v, but rears should be holding around 4v instead. Hell, push comes to shove and you don't want to tune them out and not run them, just just resistor the lines to get the output to read at 4v instead.
So your looking for something like the below, so the sensors only get a light whiff of exhaust, so they read low, like they would be in the stream after cats instead.
Short of this, then just use HP turner to turn off the SES code reading instead.
Again, rear sensor only see if the cats are reducing, and nothing more. Hence don't need the sensors in play, since they do nothing with the tune values when the the car is in either open or closed loop. So normal for the front sensor to peak up to 9V and down to 2v, but rears should be holding around 4v instead. Hell, push comes to shove and you don't want to tune them out and not run them, just just resistor the lines to get the output to read at 4v instead.
Thread Starter
Racer
Joined: Jul 2013
Posts: 351
Likes: 24
From: New York
Thanks for the reply and I understand what's going with them. Your comments confirm what I have seen by using one of the extenders with an open end and one with a perforated end. The one with perforated end seemed to work until the end fell off. Next I am going to try one like in your link with a small orifice. One question is what would happen with no orifice or opening in the extender? Would voltage stay at one level and would the computer not throw a code? My guess is the O2 sensor needs a small amount if exhaust to get the right voltage.
Race Director
Joined: Dec 2013
Posts: 12,502
Likes: 3,631
Thanks for the reply and I understand what's going with them. Your comments confirm what I have seen by using one of the extenders with an open end and one with a perforated end. The one with perforated end seemed to work until the end fell off. Next I am going to try one like in your link with a small orifice. One question is what would happen with no orifice or opening in the extender? Would voltage stay at one level and would the computer not throw a code? My guess is the O2 sensor needs a small amount if exhaust to get the right voltage.
Yes, voltage has to be keep around 4V, or will throw a code thinking that the sensor is Not working at all. This is the reason that just throwing in resistor in line works to hold the read back around 4 volts.
Thread Starter
Racer
Joined: Jul 2013
Posts: 351
Likes: 24
From: New York
Makes sense. The resistor might work but I just want it to look stock from a distance. A tune would be a good idea but I'm in a very isolated area of upstate NY and you kind of have to know someone well enough to do a tune like this and I don't. I will keep trying different extenders with different sized orifices and see if any work. If that doesn't, I'll get to know a tuner and just get it tuned out.
