I have test pipes without bungs, O2 rears have been unplugged and my car has been running fine minus the CEL.

Now I'm wondering, whats the best out of the 2 evils, No o2s, or my o2s plugged in and just ziptied up?

Probably a dumb question but its bothering me

 

Get bungs welded in.

 

It's my understanding (and if I am wrong the next 50 post will let you know) That the engine only uses the front O2 sensor to tune the engine. And it only looks for a difference between the front and back to make sure you have a cat.

 

Not on the Z, but on other cars i've run them still plugged in but out of the exhaust stream. Will give the CEL anyway, but doesn't set all the circut codes it will if you unplug it.

On the other platform, the car would try to conduct a function test of the rear O2, so we would get A/F variations at idle from time to time, randomly. Car would drop from ~15 to low 11s and stay there for almost a minute, expecting a response from the rear O2 but never getting one obviously.

Most of us ended up putting it back in the exhaust at some point and just turning off the P0420 code for catalyst efficency but not suffereing the other adverse effects.

 

I had the same (mis)understanding for a long time. The rear O2's do, in fact, affect the behavior of the ECU.

I had a problem for the longest time where one bank was reading extremely rich for no apparent reason and eventually throwing the P2A00 code. I thought it was a crack, a leak, and just about everything else because I was just sure the rear O2's had no real say-so in the tune of the car. However, I just recently disconnected the rear O2's, and the problem went away.

There's not a whole lot of shared clarity on that issue, so I figured it's worth pointing out. Especially if it can somehow prevent someone else having the same headaches I had.

 

Great Info, I have the same problem on my 370z after HFC installed. I'm going to try that

 

Please let us know how/if it affects it. I'm assuming it will throw a code if you don't disable them in the tune.

I have had these codes thrown, but haven't for some time now, though i'd suspect there are times/conditions when the banks run uneven.

 

Any HR owners completely remove their rear O2 sensors?

 

I would advise u put them back on. Check your gas mileage w/ them off. I think over time it will plummet.

Rear o2 sensors affect newer 350z. I'm pretty certain on the HR, but iono about the DE / RevUp.

Rear o2 sensor picks up the exhaust flow. I had 1 of mine unplugged and both disabled cuz one of my sensors was stripped when removing off my stock cats. Car ran fine for a while and after few days, i noticed horrible gas mileage and then CEL came on. My UpRev tuner said rear sensors was telling ECU that it wasn't getting enough fuel cuz it wasn't picking up any gas flow, and thus kept feeding more and more. I ended up running 250 miles on my tank and that's mostly highway driving to/from work. I ordered new sensors and had them plugged in and enabled again and car been fine ever since.

 

I have still have them in, thanks for the info...

Any good places to order pre cat sensors....I too stripped on and for the longest dealt with it popping out after a run. I tried using another four wire sensor to splice together with the OEM connector...didn't find anything on it and my attempt failed. Not trying to spend $300 on a sensor...

 

Amazon, probably