which O2 sensor is which? I had a b18a with 1 O2 sensor before and i simply added a second one so that my second one is the one with a green connector while the primary one still has a white connector. I read somewhere that this might be backward? Can anyone verify this? I know there must be some guru on this somewhere.
^^
I think I read this on the “common questions B16A swap” and it said NOT to use two 02 sensors. search for the post and you’ll find it, it’s in archives.
Actually, i posted that and I said you DO have to use 2 O2 sensors but now im not sure which is which on the manifold.
I guess I was thinking of this line:
“Dont bother using the b18a manifold because if you have 2 o2 sensor wires on 1 o2 sensor you will waste gas and the car will feel slower”
yeah so if you use a b18a manifold that only take 1 O2 sensor then you will have problems so use the b16a manifold instead. Now im trying to figure out which O2 sensors is which.
Ok after much research here is the answer for anyone doing a 1st gen b16a swap replacing a 1st gen b18a:
O2 sensor #1 is:
-
(C16 on the PR3 or PW0 ecu)
GREEN connector
monitors cylinders 1 & 4
-
(C8 on the PR3 or PW0 ecu)
WHITE connector
monitors cylinders 2 & 3
In the USDM b18a PR4 ecu setup the sing O2 sensor with a white connector is on C16 so dont let this confuse you. Just change the white one over to the JDM green one and add a new wire for the JDM white one.
Problem Solved.
well i had mine setup with one o2 sensor, with a splice together at the ecu side wiring harness and here are my experiences.
car ran great with no codes, fast as hell also 
also very bad gas milage, but passed emissions with stars and banners or whatever, not that that necessarily means it didnt have a 02 sensor problem
when i added a autometer a/f gauge i noticed the o2 wasnt creating a useable signal most of the time
accounting partially for the horrible fuel economy
replaced with new bosch replacment
a/f gauge worked 10 times better, and i noticed the car surged constantly cept WOT
then i jsut put the old one back on damn that **** was like 60 bux
-Toby
Originally posted by erniecars
Problem Solved.
I see where you welded the new bung hole,
but what did you weld shut?
i didnt weld anything shut but on the B-pipe i plugged the O2 sensor bung with a bung plug I got from a hardware store
I rigged it up using the single O2 sensor and connected to the ecu and jumped the wire to the 2nd o2 sensor on the ecu. The can run’s great with no code, and fast, but my fuel economy sucks major ass. i get like 150 miles to a tank. So I need a new 4-2-1 header and duel O2 sensors. I have the stock b16a manifold no downpipe. How much did that run ya for the welded bungs for the o2 sensors?
Originally posted by kincaidintegra
I rigged it up using the single O2 sensor and connected to the ecu and jumped the wire to the 2nd o2 sensor on the ecu. The can run’s great with no code, and fast, but my fuel economy sucks major ass. i get like 150 miles to a tank. So I need a new 4-2-1 header and duel O2 sensors. I have the stock b16a manifold no downpipe. How much did that run ya for the welded bungs for the o2 sensors?
4-2-1 header definintly sounds like a better option to go with
in this situation. My man at the shop just put my b16 in my car,
and he’s trying to convince me that just using the one o2 sensor
from the computer will be ok. I just don’t feel comfortable knowing
that the ecu is looking for two o2 sensors, and it will only be
reading one.
I would still get a code once in a while using one sensor. You really should hook it up right. If you leave an O2 sensor unplugged the motor will run lean which is dangerous. This welding job was $25 but I bet you could get it done cheaper. The O2 bung plugs for filling in unused O2 bungs on the B-pipe of the DC header are like 1.99 each at a hardware store.
cool, well i reviewed my vacummn lines and the map sensor was hooked up to the intake pipe, not the TB. I have to re run all my vacummn lines they are all dicked up. That should help also. Any good ideas for 4-2-1 headers for an all motor b16a? I’m willing to redo the entire exhaust system. I have a welding machine. I was thinking of the jdm header with the 2.5 collector.