Anyone else find a good way to handle cat codes on this chassis?

[PyroguyFTW]

Hey all. Since installing my P&L downpipe last year, I've been chasing issues with assorted cat codes and I'm hoping someone else has seen these and conquered them.

First, it started as a classic P0420.
Now, after trying two types of O2 spacers, I'm stuck with a handful of codes on the other side of the spectrum.

With a mini-cat, I get:
P0137: Oxygen Sensor Circuit Low Voltage (Bank 1, Sensor 2)
P0140: Oxygen Sensor Circuit No Activity Detected (Bank 1, Sensor 2)
P2096: Post Catalyst Fuel Trim Too Lean Bank 1

With a shorter normal spacer(no catalyst) I get the same codes, usually preceeded by a silent P0137.

The conditions the codes occur quickest in are when cruising around 3k with very mild load.

It also is accompanied by a minor power loss caused by excessive richness. This is usually what clues me to the silent code. Target AFR goes from 14.5-14.7 to 13.5 at cruise, and under high load target goes from ~11.5 to 11 or lower(all on pump gas, no added ethanol).

If it weren't for the rich condition, I could live with it. I'm gonna be reaching out to my tuner about this on Monday, but for now, I'm looking to see if anyone else has had this issue, and found a solution.

Thanks all!

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[Apb_pools]

Is this a 2016/va or vb chassis car? Is car tuned, flashed for said downpipe? By downpipe you mean j pipe right?

[PyroguyFTW]

Originally Posted by Apb_pools

Is this a 2016/va or vb chassis car? Is car tuned, flashed for said downpipe? By downpipe you mean j pipe right?

My bad, I didn't realize I hadn't updated my profile info. It's a 22. And it's tuned as alluded to in my post. As for downpipe/j-pipe, they're one in the same. FA20 guys nicknamed it a J-pipe due to the shape.

[Apb_pools]

Yea I dont have a pipe yet so i dont know but i did have a pipe on my 2018 and Ron tuned it out. I imagine your tuner cant do it or pipe isnt proper. ETS website also has a thing saying they cannot guarantee the code off so maybe sometimes it is the way it is for whatever reason tuning Gods decide.

I am hesitant to go jpipe and would prefer to stay oem but not sure how it would impact my expensive (both financially and timely) 550-600whp trip. Will consult with tuner and go from there myself.

[PyroguyFTW]

Originally Posted by Apb_pools

Yea I dont have a pipe yet so i dont know but i did have a pipe on my 2018 and Ron tuned it out. I imagine your tuner cant do it or pipe isnt proper. ETS website also has a thing saying they cannot guarantee the code off so maybe sometimes it is the way it is for whatever reason tuning Gods decide.

I am hesitant to go jpipe and would prefer to stay oem but not sure how it would impact my expensive (both financially and timely) 550-600whp trip. Will consult with tuner and go from there myself.

The new policy at Cobb is that anything even tangential to emissions equipment is off-limits. That's preventing the tuner from disabling the CEL.

As for power goals, it's obviously doable on the stock downpipe, however it's gonna be a limiting factor. The stock hot side is a little small for a 400whp build, let alone anything higher. Any reduction in restriction will be well founded, which is why I chose the P&L downpipe over ETS. As they use a 3.5" inlet, that was a big driving factor for my choice. It's not a big gain, but given the exhaust will cool a little bit, it should be worth a bit of power. The post cat temps being lower should keep the exhaust gas velocity up.

[Apb_pools]

So aside from a pretty orange light on your dash what is the downside of having these CELs come on? Seems like a no brainer to me, pay 1200$ for more power and orange LED.

[ChainringCalf]

Originally Posted by Apb_pools

So aside from a pretty orange light on your dash what is the downside of having these CELs come on? Seems like a no brainer to me, pay 1200$ for more power and orange LED.

That orange LED also comes with locking you out of cruise control, which is another minor annoyance.

And, what happens when you trigger another "real" code that you do actually want to see? The light can't turn more on, so you'd never know.

[PyroguyFTW]

Originally Posted by ChainringCalf

And, what happens when you trigger another "real" code that you do actually want to see? The light can't turn more on, so you'd never know.

This is exactly why it irks me when people say "ignore the CEL"

But, 3rd point:
A p0137 comes with a rich condition to ensure the cat is up to temp. It riches my target AFRs by a full point, which kills power, fuel economy, and drivability.

[Apb_pools]

So some basic questions:

1. do you have both oxygen sensor properly secured into the P&L j pipe AND do you have the catalytic converter in there (between front and rear oxygen sensors).
2. is this an ots tune or a proper custom e tune?
3. is anything (hardware setup wise) different now from when you first flashed the tune?

[CXRs]

Delete

[PyroguyFTW]

1 and 2 were both covered in my original post. Nothing has been changed since the original tune. Did you have these codes before, or are you just trying to get clarification on the situation to see if improper installation was the issue?

[Chuck H]

Had this all typed up, and then accidentally went back after previewing without hitting submit.

Anyway, I have a similar setup to OP, except with an ETS J-pipe and had similar issues. I installed mini-cat extender, the straight one, not a right angle, and it was a pretty decent partial fix. I went from having the CEL come on every couple of days to only occasionally coming on. I was checking it one time and discovered that I had a couple of the silent codes -- I think the 0137 and 0140, but can't remember for sure.

I think I've had the mini-cat for about 6 months and 3000-4000 miles now, and the CEL has only come on twice with the dreaded 0240. It might be coincidence, but both times were on long highway trips after I really romped on it in 3rd and 4th.

Of course, the last time the CEL came on was a few days before I had to get the car inspected, and I was worried about passing. But I cleared the codes and got enough time in that all the ready indicators were good and no silent codes, so good for another year.

I was researching for a better fix than the hit-or-miss mini-cat, and didn't see any sort of viable candidate to swap where the GESI cat is now, before the bend. About the only thing I could think of is adding a second GESI cat right after the bend and moving the 2nd O2 sensor further downstream. But not sure if that would require an O2 sensor extender cable as well, and it's a VERY expensive experiment that's not guaranteed to work. So I'll probably live with it until I can't any more.

The other thought I had was going back to the OEM cat assembly and creating a Frankenstein J-pipe by mating it to the back half of the ETS J-pipe right after the downstream sensor. But that would negate most of the gains from the higher flowing cat and the OEM cat part is insanely overpriced from the dealership. I made the mistake of letting my tuner toss my OEM exhaust stuff, so wasn't going to buy a new one.

[Apb_pools]

YouTube

YouTube

[PyroguyFTW]

Originally Posted by Chuck H

Had this all typed up, and then accidentally went back after previewing without hitting submit.

Anyway, I have a similar setup to OP, except with an ETS J-pipe and had similar issues. I installed mini-cat extender, the straight one, not a right angle, and it was a pretty decent partial fix. I went from having the CEL come on every couple of days to only occasionally coming on. I was checking it one time and discovered that I had a couple of the silent codes -- I think the 0137 and 0140, but can't remember for sure.

I think I've had the mini-cat for about 6 months and 3000-4000 miles now, and the CEL has only come on twice with the dreaded 0240. It might be coincidence, but both times were on long highway trips after I really romped on it in 3rd and 4th.

Of course, the last time the CEL came on was a few days before I had to get the car inspected, and I was worried about passing. But I cleared the codes and got enough time in that all the ready indicators were good and no silent codes, so good for another year.

I was researching for a better fix than the hit-or-miss mini-cat, and didn't see any sort of viable candidate to swap where the GESI cat is now, before the bend. About the only thing I could think of is adding a second GESI cat right after the bend and moving the 2nd O2 sensor further downstream. But not sure if that would require an O2 sensor extender cable as well, and it's a VERY expensive experiment that's not guaranteed to work. So I'll probably live with it until I can't any more.

The other thought I had was going back to the OEM cat assembly and creating a Frankenstein J-pipe by mating it to the back half of the ETS J-pipe right after the downstream sensor. But that would negate most of the gains from the higher flowing cat and the OEM cat part is insanely overpriced from the dealership. I made the mistake of letting my tuner toss my OEM exhaust stuff, so wasn't going to buy a new one.

I've got a plan to trim down an O2 spacer as far as possible to see where it takes me. I'm not sure when I'll have the time, but it's a work in progress. Even a 45mm spacer is throwing codes, so I'd like to get it as close to 25mm as possible in the hopes that will keep my fuel terms healthy.

[Chuck H]

Originally Posted by Apb_pools

https://m.youtube.com/watch?v=AXPBYlevrt8

I love Joey's videos, but I think he's off-base on this one. Since he's not getting codes from his J-pipe, there's no way to tell if that extender would help. But based on everyone else's experience with spacers, they're not to solution on the FA24.

I was searching around and found some recommendations for HJS catalytic converters. But OMG are they expensive!

https://www.fabspeed.com/additional-...ic-converters/

I'm guessing it would be more expensive to have a GESI J-pipe "re-catted" with an HJS cat than to buy the J-pipe in the first place. If it would kill the dreaded CEL, it might be worth it, though.