Another CBFA Downpipe Post

[the_horak]

Here's what I'm thinking: I want a catted downpipe. Often in the past, I have fitted high-flow (200 cell) universal cats and I've never had a CEL. What about two universal cats in the downpipe? I know that a cat will add restriction, but 200 cell is minimal. A 3" well-flowing downpipe with two cats should still be a sweet upgrade and sufficient for the stock turbo and a basic tune.

So what are your thoughts? Anyone do this? Do you think it will minimize or prevent a CEL? What are everyone's thoughts?

 

[the_horak]

No takers? Haha

 

[GolNat]

What is your overall goal?

Buy a downpipe with a high flow cat.

 

[the_horak]

What is your overall goal?

Buy a downpipe with a high flow cat.

A catted dp is something I've been looking into. My ultimate goal is minimizing a CEL so that the polar bears are happy. I figure if each O2 sensor is seeing progressively better readings as they go down the pipe, I might be good. The OEM pipe has 2 restrictive cats, so 2 high-flow may help. Maybe still need a spacer on #3? Honestly I don't know what the ECU wants to see.

It seems like i'm not gonna have a solid answer til I start playing with it and seeing how to balance. Probably gonna buy catted dp with another universal cat, spacers and a catted spacer and see what works. I don't want to play the game of the CEL with inspections.

I just wanted to throw this out there and see if anyone has tried this with success or failure. Or maybe someone knows why this wouldn't make any difference. Looking for some experience from others to make my life easier haha

 

[BudgetPhoenix]

Aftermarket cats aren't guaranteed to keep the CEL away, especially such free flowing ones like a 200 cell. Heck people have a hard time removing the CELs using an O2 spacer. You might get rid of the P0420 but you'll start throwing other o2 sensor lean/rich codes depending on the spacing and orientation of the o2 spacer if its not perfect. The ECU on these engines are sensitive to this.

A lot of people just put their stock downpipe on for emissions and go back to catless after

 

[GolNat]

I ran a dp with a high flow cat and spacer on #3 sensor and didn’t have any emissions related codes.

 

[the_horak]

Aftermarket cats aren't guaranteed to keep the CEL away, especially such free flowing ones like a 200 cell. Heck people have a hard time removing the CELs using an O2 spacer. You might get rid of the P0420 but you'll start throwing other o2 sensor lean/rich codes depending on the spacing and orientation of the o2 spacer if its not perfect. The ECU on these engines are sensitive to this.

A lot of people just put their stock downpipe on for emissions and go back to catless after

To that point, driving around with a CEL for P0420 doesn't impact performance?

I ran a dp with a high flow cat and spacer on #3 sensor and didn’t have any emissions related codes.

So sensor #2 went after the cat and then #3 followed with only a spacer?

 

[GolNat]

To that point, driving around with a CEL for P0420 doesn't impact performance?

So sensor #2 went after the cat and then #3 followed with only a spacer?

CBFA has 3 sensors. One after/in the turbo, one before the cat and one after the cat. I put a spacer on the 3rd one after the cat.

 

[jay745]

I doubt this would make any performance difference honestly. Not worth the effort.

 

[the_horak]

CBFA has 3 sensors. One after/in the turbo, one before the cat and one after the cat. I put a spacer on the 3rd one after the cat.

View attachment 256011

I would have imagined that the cat would go between the turbo and the #2 sensor, but looks like that's not how it is.

 

[This is Ryans face]

Aftermarket cats aren't guaranteed to keep the CEL away, especially such free flowing ones like a 200 cell. Heck people have a hard time removing the CELs using an O2 spacer. You might get rid of the P0420 but you'll start throwing other o2 sensor lean/rich codes depending on the spacing and orientation of the o2 spacer if its not perfect. The ECU on these engines are sensitive to this.

A lot of people just put their stock downpipe on for emissions and go back to catless after

Can attest to the spacer not doing a fucking thing here. We have no emissions testing here in FL, so I run a catless DP. I didn't think I had, but apparently I had fitted the midpipe O2 sensor with a spacer for shits, and whenever I kicked the tune back into stock settings, it would still eventually throw a "too rich" code (probably why I thought I chucked the spacer at some point). Maybe a combo of a spacer and hi-flo cat might help OP here, but my take is not even the 42 draft design spacer did fuck all for me.

 

[uglybastard]

My ultimate goal is minimizing a CEL so that the polar bears are happy.

If this is your ambition, stay stock.

 

[uglybastard]

But if you want an catted aftermarket dp, do as GolNat indicated and you will have low chance of CEL.

 

[the_horak]

Can attest to the spacer not doing a fucking thing here... ...Maybe a combo of a spacer and hi-flo cat might help OP here, but my take is not even the 42 draft design spacer did fuck all for me.

It blows me away. How many different experiences are out there with people using an aftermarket downpipe. Some people have no issues at all and some people can never get it to work. I appreciate the reply, and it really helps me to see that this is going to be trial and error If I go down this route.

But if you want an catted aftermarket dp, do as GolNat indicated and you will have low chance of CEL.

That's what I'm going to do. I get where you're coming from about just staying stock, and maybe that is the correct answer. If I'm going to do a tune though, it would be nice to have the downpipe. I'll probably just start with one cat and one j-spacer kit and go from there.

 

[the_horak]

PS @uglybastard I love the profile photo hahaha