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Guest Message by DevFuse

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O2 sensor location EA81 SPFI

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3 replies to this topic

#1 tweety


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  • Euroa Victoria Australia

Posted 12 July 2013 - 04:31 AM

Close to installing my SPFI on my EA81. Waiting on a few things in the mail including a new O2 sensor from the states.


Would like to brainstorm you guys and my local Subie forum Ausubaru for the best location for the sensor.  This is a trike and in Oz trike arent subjected  to anti pollution requirements. So the custom twin exhaust has not cat.


There is a connecting pipe between both exhausts.  This pipe is only 7" (180mm) from the exhaust manifold. I'm assuming it best be placed about 4" from the exhaust manifold meaning 2" from the connecting pipe? On a 45 degree angle. What are your thoughts?







#2 tweety


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Posted 12 July 2013 - 05:13 AM

Then I found this.



Mount the O2 sensor in the exhaust system at least 18 inches downstream from the exhaust port. If you anticipate

high EGT's (over 800C), run a turbocharger, run at high RPM for extended periods of time or plan on running leaded race
fuel then you must mount the sensor at least 36 inches or more
downstream of the exhaust port as all of these can cause the sensor to
overheat. On turbocharged engines the UEGO sensor must be installed after the turbo charger, if not, the pressure differential will greatly affect the accuracy of the unit.
For accurate readings, the sensor must be mounted before catalytic
converters and/or auxiliary air pumps. To prevent collection of liquids
between the sensor housing and sensor element during the cold start
phase, the installation angle should be inclined at least 10° from
horizontal with the electrical connection upwards.
I dont intend to supercharge or turbo charge it. But 18 inches from exhaust port?  That would leave it mounted ither after the connencting pipe before the muffler or after the muffler?????

#3 mikaleda


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  • priest lake, Idaho

Posted 12 July 2013 - 10:40 AM

They are usually mounted in the front of the cat. I would just put a bung right in front of the muffler and put it there

#4 tweety


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Posted 12 July 2013 - 06:23 PM

thanks Makalida.  Think you are right. The other idea I had was using two O2 sensors, one on each side and wiring them up togather but dont know if that would work with voltage etc. to get an average of mixture richness/leaness from both banks


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