O2 sensor re-location???

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I am installing Bellanger Headers and hi flow cats on my 05 SRT I already have Corsa exhaust. I have heard a lot of horror stories about when you relocate the down stream O2 sensor to behind the cat and under the side sill. I hear that they get to hot under there and the wires rubbing on the insulation could short out and you will end up with the check engine light when that happens.

My question is, can you relocate the sensor to the far end of the exhaust beyond the mufflers? There is a lot of room behind the second muffler and you get out of the insulated area if you are in the tail pipe.

It would be easy to run the wires down the transmission tunnel and out to this location.

I just don't know if the sensor would function well that far down stream and beyond the mufflers like that.

Anybody have any thoughts on this.
 

dave6666

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I know in a Gen 2 it is a response time issue. Even just moving them past the merge collector inside the frame rail on the Belangers to the turnout on the outside of the frame rail. I can't imagine that concept does not apply on the SRT. So my unscientific opinion is moving them to the turnout would cause problems.
 
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Thanks. But, on my gen 2 the down stream o2 sensor is behind the first muffler in the rear wheel well.

I still have the sensor that is in the header, I am looking to move the one that is behind the first cat on my SRT, not the one that is in the header.
 

dave6666

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If it is used for tuning then location may matter. Also, what is your plan for wiring harness length, assuming your proposed sensor location may exceed the reach of the factory wiring? And is there a route to run the wire to the new spot without exposure to sill heat? Regardless of the sensor location itself?

I do on my GTS have the rear sensors at the turnouts, not above the axles. Side exhaust conversion.
 
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If it is used for tuning then location may matter. Also, what is your plan for wiring harness length, assuming your proposed sensor location may exceed the reach of the factory wiring?

I was going to splice in wires and run them down the transmission tunnel and out to he rear wheel well.
 

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Here are some pics of what I did on the GTS. I do think the underlying issue of if the rear sensors are used for tuning may need to still be answered (by someone other than me), but the mechanical/electrical aspects remain the same.

I would solder and not use crimp terminals, for best life of that mod. I would also use melt adhesive lined heat shrink for moisture seal. McMaster Carr has it cheap.

It was tough access to do some of the work up in the tunnel soldering and heat shrink etc, but absolutely no problems since I did the work 1 year ago.

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Thank you very much!

What is your reasoning for cutting and splicing the chassis side of the wiring instead of just making the wires on the sensors longer??
 

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Thank you very much!

What is your reasoning for cutting and splicing the chassis side of the wiring instead of just making the wires on the sensors longer??

Supposedly the sensor wires themselves are not copper (steel alloy?) and they are very sensitive to alteration. Like in a bad way. Rule is do not mess with them.
 

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I have that setup. GenIII 05 w/Balangers, Highflows and Corsa. I had to have DcPerformance turn off the secondary 02 sensors. I sent them my PCM and they flashed it for me turning it off. I found absolutly no way to keep the sensors from burning up (tried cat simms heating insulation etc) also Longer wires will screw up the sensors by changing the resistance load. Since then I have had 0 (ZERO) problems with them! Hope this helps. If you are installing Balangers for the first time right now there is some heat shielding you want too do also. PM me with questions.
 
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Well I just talked to Dan at DC performance and he said he has tried this before, putting the rear o2 in the tail pipe on an SRT. he said he computer didn't like it because the sensor doesn't heat up quick enough.

I guess I will have to get them closer to the cat???

Thanks for all of your input and pictures Dave!!
 
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Thanks Shandon, I think that I may just take your advise.
I will be putting this car on the dyno very soon and I hope to be putting down around 700RWHP. I expect that I will need to have my air fuel adjusted after changing the headers and cats and putting a ported throttle body on. When I send it to DC to get tweaked for the air fuel I will just have the rear sensors turned off.
 

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My '09 has headers and no cats. I put the downstream 02's in the 90 turnouts right at the outside of the bend. I had to lengthen the 02 wires by about 12" for them to reach. Solder would not stick to the 02 wires so I had to crimp them. To protect the wires, I bought some 1/4" asphalt coated fabric wire loom.

I have two spark plug anti-foulers on each 02 to pull it out of the exhaust stream. The 02 sensors heat up and stay warm but aren't exposed to the exhaust stream. No check engine light yet.
 

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dave6666

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Supposedly the sensor wires themselves are not copper (steel alloy?) and they are very sensitive to alteration. Like in a bad way. Rule is do not mess with them.

My '09 has headers and no cats. I put the downstream 02's in the 90 turnouts right at the outside of the bend. I had to lengthen the 02 wires by about 12" for them to reach. Solder would not stick to the 02 wires so I had to crimp them. To protect the wires, I bought some 1/4" asphalt coated fabric wire loom.

I have two spark plug anti-foulers on each 02 to pull it out of the exhaust stream. The 02 sensors heat up and stay warm but aren't exposed to the exhaust stream. No check engine light yet.


:omg:

:dunno:

;)
 

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Just comfirming what you suspected. And I'd rather not hack into my wiring harness so I took a chance with the sensor wiring. So far there doesn't seem to be a problem with lengthening the wires.
 

Darbgnik

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Supposedly, the second O2 is just for emissions, and the check engine light is just for cat maintenance. Some people just tie them up outside still connected so they sniff fresh air on gen 3s with no lights coming on.
 

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Supposedly, the second O2 is just for emissions, and the check engine light is just for cat maintenance. Some people just tie them up outside still connected so they sniff fresh air on gen 3s with no lights coming on.

That didn't work for me. Car ran fine but I got a check engine light for sensor temperature or something like that. Went away after I put them back in the exhaust pipe. Tying them up like that seems kind of half a$$ed anyway.
 

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Just to chime in here, I bought aftermarket O2 sensors for my 01 Stratus - they didn't have a plug, as at the time, aftermarket wasn't making specific application 02's yet. I crimped the aftermarket wires into the original wires as solder didn't stick to them (I now know why, reading this thread) but three years later, still haven't had a problem with it. I think the theories of changing resistance on 02 sensors is all myth - it's just wire. If done correctly, a crimped connection can actually have LESS resistance than just plain wire, but the differences are so minor - down to a milliamp or less - that the computer isn't smart enough to even notice.

Jeff
 
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