[cajunzl1]

Adding an AEM wide band o2 gauge on my ZL1, my muffler shop is giving me grief about putting it before the primary cat. He said it would be tight getting it welded and servicing the sensor.

He would like to put it after the Cat. I recently watched a CSP video and Andrew installed it in place of the rear 02 Sensor.


Is the AFR reading that much different after the Cat to make a difference tuning? also does anyone have photos of their O2 location before the Cat??

Thanks

[Mark114]

This thread has some options:

https://www.camaro6.com/forums/showthread.php?t=556095

[cajunzl1]

Thanks, I did think about the passenger side as it's flanged.

I'm still curious if the AFR reading is dramatically different before and after the Cat?

All of the Tuners on YouTube seem to have it sampling the tailpipes...

[Eric10905]

Mine is an SS, and can't answer the question on how it may or may not alter readings if done after the cat. I can only say due to other issues, i had to put mine in the factory bung after the first cat for my first phase of mods. Tuner told me it was ok, and i made sure he knew that's where it was when i sent him those log files. Car ran fantastic, no issues. But this might vary depending on your tuner... idk.

[cajunzl1]

Thanks, so it was the 2nd bung you used?

[Eric10905]

Originally Posted by cajunzl1

Thanks, so it was the 2nd bung you used?

Yes, counting from head down. The factory bung after the first factory cat. You can’t mess with the factory ones before cats, as I understand.
Important, And you need to have the tuner turn off those same sensors after cats in the tune before you disconnect them and use one of those bungs for your wide band. Otherwise it writes an unerasable emission error code to the ecu. Or so I understand.

[cajunzl1]

Thanks

[JANNETTYRACING]

Originally Posted by cajunzl1

Adding an AEM wide band o2 gauge on my ZL1, my muffler shop is giving me grief about putting it before the primary cat. He said it would be tight getting it welded and servicing the sensor.

He would like to put it after the Cat. I recently watched a CSP video and Andrew installed it in place of the rear 02 Sensor.


Is the AFR reading that much different after the Cat to make a difference tuning? also does anyone have photos of their O2 location before the Cat??

Thanks

The correct location is between the manifold and front cat.

All Professional tuners require this location.

Youtube tuners not so much LOL.

If your muffler shop can't handle it don't settle for half ass, find a qualified welder.

We install them in this location regularly with no issues what so ever.

Ted.

[Joshinator99]

Originally Posted by JANNETTYRACING

The correct location is between the manifold and front cat.

All Professional tuners require this location.

Youtube tuners not so much LOL.

If your muffler shop can't handle it don't settle for half ass, find a qualified welder.

We install them in this location regularly with no issues what so ever.

Ted.

[cajunzl1]

thanks !

[cjperformance]

The entire purpose of a catalytic converter is to eliminate excess hydrocarbons (fuel) and other combustion products (NOx/CO/etc...) by combining/burning it with leftover O2. So the cats will absolutely affect the readings of an O2 sensor placed after the cats.

The reason the factory ones exist after the cats is solely to ensure the cats are doing their job.

If you watch your AFR, the ECU will go rich/lean/rich/lean alternating just to feed the cats enough O2 to do their job, which is why you have to take it out of closed loop when tuning.

I don't have an image for you, but I put mine on the passenger side, sort of on the inboard side. You could also put it on the outboard side if I recall. The driver side is viable too, but taking the cat section out of the driver side was going to be a PITA due to the slip fit, where the pass side was bolted together.

[cajunzl1]

So CJ, you removed the passenger cat when installing?

[cjperformance]

Originally Posted by cajunzl1

So CJ, you removed the passenger cat when installing?

Yeah, there was no way i was going to be able to drill the hole and weld the bung with it on the car.

I took a sharpie marker under the car with everything still bolted up. Found a place where the sharpie would fit to check for clearance. Once i was happy with the location and orientation, i marked the pipe with the sharpie, removed the section, drilled the hole, etc.

You will get metal shavings in the cat if you dont remove it to do this.

I will say though, there were more ideal placement options on the drivers side, but pass side was easier to remove.

You may want to prepurchase the header/manifold gasket. Its a crush style, and if you damage it it will leak and your o2 sensor readings will be off.

[cajunzl1]

Great Idea, i'll try and locate the part numbers!!