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Location of 1st Oxygen Sensor?

3K views 12 replies 3 participants last post by  riva2model64 
#1 ·
Hi all,
I have an 06 Spec V with a 2JR Spyder header. It has two ports to install an oxygen sensor, and I was wondering which port should the oxygen sensor be installed in? I've some say the lower, some say the upper.

Here's a picture:https://www.2j-racing.com/catalog/product/gallery/id/556/image/2445/

Looks like the FSM has it installed in the collector pipe of the stock catted manifold.
 
#3 ·
Thanks, and that does make sense about putting it in the collector. However, on the picture it says about the port in the collector that it is a "longer secondary 02 port to assist in no-CEL." Could that potentially mess up the signal the first oxygen sensor sensor, the A/F sensor, is sending to the engine?
 
#4 ·
that is to keep the check engine light off. there are ways around it, mainly, in the older models with both ports in the header, they need to read different. on the 04-06, the secondary sensor is in the mid pipe, and needs the anti-fouler installed so you dont get the light. again, the sensors need to read different, not so much what they read, as the primary is the one the ecu uses for afr's, but the secondary, wherever it may be, needs to read different so you dont get the light
 
#5 ·
basically, on an 06, you can put it up high, with no issue, only reading one pipe, the longer bung on the secondary is for the 02-03. in your instance, if the upper is closer to the exhaust stream, put it there, as it needs to read correctly to adjust AFR's. then space the secondary in the midpipe so you dont get the check engine light. IIRC 2J sells pre-drilled anti foulers, or you can pick them up at almost any auto parts store, drill it out, and be light free
 
#8 ·
I may have been less than clear, to break it down, the 06 sentra has an AFR sensor in the upper exhaust manifold, that is the O2 sensor as well, but the ECU uses the sensor to adjust fuel trims, so it needs to be directly in the exhaust stream, even if it is only one primary runner. IF the lower bung is spaced, you need to use the upper on an 06, so your fuel delivery will be correct. you will need to add a spacer to the secondary O2 sensor, in the midpipe, if you do not want a check engine light. this is contrary to my first reply to you, as at that time I did not know you had an 06, and replied generically. apologies for that.
 
#9 · (Edited by Moderator)
No worries - the header was designed for a general Spec V rather than specifically an 06, which was why I asked for your folks' help :)

Unfortunately I had the primary O2 sensor running on the lower bung for several months now. Hope it didn't cause any damage. I was going to change it to the upper one, but was previously advised against it. Going to swap it ASAP. Thank you!
 
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