WB O2 sensor placement

MG8T7GN

Member
Joined
May 25, 2001
I'm thinking of building that wide band O2 sensor box on the DIY-WB page. Is there a preferred location for the sensor? Does it have to be about where the stock sensor is located or is in the downpipe close to the turbo an acceptable location? Thanks.

Mark
 
Originally posted by MG8T7GN
I'm thinking of building that wide band O2 sensor box on the DIY-WB page. Is there a preferred location for the sensor? Does it have to be about where the stock sensor is located or is in the downpipe close to the turbo an acceptable location? Thanks.
Mark

I've tried mine in several locations,
In the oem bung, just post where the converter would be and at the very end of the pipe, and haven't seen any huge change.

Later today when it warms up, I'll be running two WBs at a time and seeing if there is any detectable change.

It's not really a big deal anyway.
You tune for what your car likes, so as long as any error is constant then there is no reason to worry.

Part of the trick to the WB is that it's operating temp, is 800dC (yes, it's that hot). So it's not effected by EGT, unless your running insane EGTs and have the WB right at the port.

One thing that will happen is that the further down pipe the sensor is, the more it will average the readings, the longer the pulsations dilute with each other there is time for more reactions to take place post chamber.
 
So...

.. what would be the optimal location on my vehicle? I have a '98 Cobra. It's currently sitting in the X-pipe, in one of the stock O2 bungs by the crossmember. I did have a couple O2 bungs in the collector, but I welded them up since they weren't being used. The shop that wired up the Speed-Pro installed the WB O2 in that location (True Blue Perf. in Raleigh, NC).
 
WB placement

FWIW, I think the Wb sensor is not designed to work in a temperature that's above 1200-1300 degrees, thus the placement down in the DP. [There was a recent post on this and it was discussed in detail by several users.]
Directly under the turbo is too hot, IMO. My EGT meter at that same location runs consistently 1500 to 1600 @WOT.:cool:
 
Re: WB placement

Originally posted by Chuck Leeper
FWIW, I think the Wb sensor is not designed to work in a temperature that's above 1200-1300 degrees, thus the placement down in the DP. [There was a recent post on this and it was discussed in detail by several users.]
Directly under the turbo is too hot, IMO. My EGT meter at that same location runs consistently 1500 to 1600 @WOT.:cool:

<sigh>
you missed my posting.
The NTK (Honda) operate at 800dC, or about 1700dF. All you do by running em warm is save thermal loading of the heater circuit.

But, to actually go further with some facts.

this morning I hooked up two WBs, to my car..
One pre turbo, and one post turbo by about 6'.
At idle cruise, you could see the one sensor trail the other.
At WOT they tracked as close as I could test to the same AFR.

Granted, this was visual stuff and not data logged, but close enough in my book.

I was expecting more of a change then what I saw, but the facts are in.
 
Thanks for all the replies. I'll scrounge around for a stainless bung and have it welded in the down pipe.

Mark
 
So, the OEM O2 bung is ok? Is that what you are saying bruce? I don't wanna weld on my nice ceramic coated pipes unnecessarily...
 
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