It's getting to the time where my transmission is gonna be replaced, and I decided I'll have him gut the precats while he's under there. I'm pretty sure the y-pipe needs to come off anyway, so might as well take the extra bit of time to shove in a screwdriver and break the precats.

Anyway, I'm buying the stuff in advance, and I'm wondering if these O2 sims will fit. Is there enough room for these to stick out that far? Thanks guys

 

Those are not sims, they are extenders or spacers. I didn't need to use them on my car, so I can't say with certainty whether they will fit. I kinda think they will. If you do need then, it would be on the downstream sensor.

 

That's not how you gut the cats lol

 

yea screwdriver will take 2 days and not entirely gut them...

spade drill bit 18" and a corded drill

and look harder for O2 sims, they pop up from time to time but not easy to find

 

I thought these might work since there’s a tiny hole to only let a small amount of exhaust gas to be read.

 

I've seen some guys use the foolers before, with some good results. I can't say they would work because i have use sims.

 

I use a modded $5 Dorman HELP spark plug nonfouler which leaves the rear O2 fully functional. The goal is relocating and slightly blocking the rear O2 from the exhaust flow, which puts the catalyst performance/efficiency back within Nissan's range. Poof, out goes the light.

I'm not quite sure what a simulator could be. Perhaps the phrase means to "simulate" catalyst efficiency (with a nonfouler or threaded tube)

 

An O2 Simulator is an active device/circuit - it manufactures the voltage waveform that your ECU expects from the rear O2 sensor, thus fooling the ECU into thinking that your precat is working properly.

Nonfouler/extender is a passive device - it moves the rear O2 sensor out of the exhaust stream, thereby making the voltage wave generated by the sensor flat/proper. As a result, the ECU thinks your precat is working properly.

 

in hindsight the extender/spacer seems more efficient and less hacky and also could be seen less reliable?... but... where is it being moved like literally just a tiny bit farther form centerline ?? i dont think position on the run matters, just how far the sensor is dipped into the center of the exhaust tube.

and whats the ratio on the extenders working? i feel there's a big gray area that the sensor could still detect problems...even if it has been moved (extended)

 

This visual may help. Your unscrewing the rear O2 sensor. Screwing in the spacer/nonfouler to the same hole that the rear O2 sensor came out of. Then screwing the rear O2 sensor into the spacer/nonfouler.




Now the rear O2 sensor has less exposure to exhaust gas. Which means the readings reported back to the ECU reflect better catalyst efficiency.

Note: None of this has anything to do with fuel trim. Because fuel trim is determined pre-catalyst via the front/precat O2 sensor. Can't calculate fuel trim post catalyst, combustion gasses are supposed to be reduced by the catalyst. Calculating fuel/air mix post catalyst would trigger a lean condition, adding way too much fuel.

Also, there are different lengths. In some cases, too long may cause a fitment issue hitting the floor, sticking out below, etc. Too short, you may not get the desired results because its not out far enough. So so some measuring prior to install to determine what length is right.

 

this is all good to know thanks for the info !, in hindsight think i would have considered this more before splicing an O2 sim in, but for now fingers crossed.

i kinda like the extender better now , its more of a passive fix, i just dont know how a lil movement away from the center of the fumes can help w the code?? i mean its the same gutted exhaust ...its confusing how sensitive it is , like with the extender it seems not solid in the sense, ok one day it didn't trip, but then the next day it does... it dosent seem reliable to me...

 

What is your objective with the foolers/sims? Are you just trying to keep the SES lamp off? Or do you need to pass emissions?

 

It's to prevent a CEL. I don't have emissions where I live.

 

Im literaly using extenders on both of my rear 02 sensors (federal). if the first 02 sensors reads 14.v then the second sensors read 14.v then th3 catalytic converter isnt doing its job. by using the extenders, they are physically pulling the rear 02 sensors out of stream while giving them a taste instead of the whole reading. while my front 02 sensors are always changing in readings, Both rear sensors always say about 3v and steady no matter how hard i rev. No codes here and i had both codes for left and right precats.

 

Heres the ones i use, amazing for clearence probs.
https://www.amazon.com/gp/aw/d/B00OXWYWK0/ref=yo_ii_img?ie=UTF8&psc=1

 

You may run into one of these on the #2 sensor
O2 Oxygen Sensor Nut Adapter in Manifold for Nissan Infiniti PK of 2 Ships Fast eBay
https://www.ebay.com/p/O2-Oxygen-Sensor-Nut-Adapter-in-Manifold-for-Nissan-Infiniti-PK-of-2-Ships-Fast/1737500550?iid=151916126611&rt=nc

If so an adapter may not clear the lip.

 

Reason I asked is I could flash your ECU to disable CEL for the pre-cats if you're interested. It might still throw the code but it wouldn't light up the dash. I'm testing the thresholds for the DTC logic but it's been frigid up here and I haven't been able to confirm whether the adjustments are successful

 

I'll let you know if I'll go that route. But for now, I think I'm gonna wait until spring because there's an opportunity for me to do it for basically no labor cost.

 

thanks for the info, it makes sense but it seems something so sensitive cant be so simple but maybe its just down to the voltage readings. how many miles have u been running that way?