FYI - Gutted Cats May Cause p219a Code

[Fat_Joe]

For the last several months, I’ve been dealing with code P219A on my 2021 Mustang Mach 1 equipped with a Whipple Gen 5 Supercharger. Unfortunately, my stock catalytic converters clogged up, and I took the cheapest route to fix the issue — gutting (hollowing out) the cats while keeping the factory housings in place.

Everything seemed fine until I started getting an intermittent P219A code (Air/Fuel Imbalance on Bank 1). Great, I thought. I tried all the usual tests— swapping fuel injectors, O2 sensors, etc., between Bank 1 and Bank 2 — but the imbalance stayed on Bank 1. I even tried a custom tune hoping that might resolve the issue, but no luck.

That brings me to this past weekend when I decided to reinstall a pair of stock catalytic converters. Let me tell you, the difference was night and day. The car idles and drives so much smoother — even my wife noticed. On top of that, the imbalance on Bank 1 is completely gone. I verified this after running almost a full tank while monitoring the air/fuel imbalance ratio on Bank 1 with an OBD2 scanner — it stayed perfectly at 0 the entire time, just as it should. Crossing my fingers that these stock cats lasts longer than the first set.

I’m posting this to help anyone else who might be dealing with the same issue while running stock headers and gutted/hollowed-out cats. I’m not sure if this is specific to forced induction setups or if it could happen on naturally aspirated cars too, but it’s something to keep in mind.

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[HKusp]

Just curious, and not looking to throw shade, who tunes your car?

 

[Zrussian13]

Did you run defoulers with the gutted cats?

 

[Fat_Joe]

Just curious, and not looking to throw shade, who tunes your car?

Got this car back in May at 16k miles. I was told the Whipple was placed on at around 10k miles and then custom tuned my a local tuner on a dyno. Pretty sure that may have contributed to the short life span of the original cats. (The car popped and crackled so much on deceleration).

A month into ownership I asked Whipple for their latest calibration and got that loaded on the car. No more pops or crackles, seemed to run smoother. Shortly after I discovered the cats plugged up. I gutted them, code popped up. Tried the custom tune, code didn't pop but I could see the imbalance values being over the threshold. Put the stock cats on the car and the Whipple tune back on the car as the custom tune was for the offroad setup. No more issues.

The custom tune was by a well known tuner that a lot of folks around here recommend but I won't disclose the tuner as this was for an offroad setup and I lived in a state that doesn't do emission testing

 

[Fat_Joe]

Did you run defoulers with the gutted cats?

Yes. That didn't work. I even tried turning off FAOSC in the calibration as that logic uses the rear o2s to calibrate the front o2s. And I figured having no cats, would throw that off.

 

[stang17]

If/when the stock cats fail again, I'd suggest going with the GESI Gen 2 UHP cats. I had my stock cats fail within 2,000 miles and regular Kooks non-green cats fail in 700 miles running the supplied whipple tune.

Been upwards of 7,000 miles now at 800+ hp and these GESI cats have showed no sign of failing or giving off that sulfur cat is going smell.

Kooks sells them rebranded as their HO Green Cats with connection pipes attached making it easier to swap in/out.

 

[Fat_Joe]

If/when the stock cats fail again, I'd suggest going with the GESI Gen 2 UHP cats. I had my stock cats fail within 2,000 miles and regular Kooks non-green cats fail in 700 miles running the supplied whipple tune.

Been upwards of 7,000 miles now at 800+ hp and these GESI cats have showed no sign of failing or giving off that sulfur cat is going smell.

Kooks sells them rebranded as their HO Green Cats with connection pipes attached making it easier to swap in/out.

Thank you for that tip. I know it's not a matter of "if" but "when" they are going to fail again. The latest calibration from Whipple doesn't pop and crackle like the original one which I am sure drastically decreased the life of the cats. Does your car make pops on deceleration?

Also are you referring to these? https://kooksheaders.com/products/11513400

I assume you are running the kooks long tube headers too right?

 

[stang17]

No crackles or pops. I do have the Kooks 1 7/8 headers with the GESI connection pipes.

Have to make sure you get the HO Green and not just Green.

3" Kooks H.O. GREENCATS Catalytic Converter 7" Long Certified to EPA S – Kooks Headers https://share.google/DeNDQ054a6VLQAZxd

 

[Fat_Joe]

No crackles or pops. I do have the Kooks 1 7/8 headers with the GESI connection pipes.

Have to make sure you get the HO Green and not just Green.

3" Kooks H.O. GREENCATS Catalytic Converter 7" Long Certified to EPA S – Kooks Headers https://share.google/DeNDQ054a6VLQAZxd

Ah okay. Yeah then, mine will probably go out sooner than I thought.

Did you get the competition connection pipes and then have someone weld those cats in? Seems like a way to save a good chuck of change than buying the connection pipes with the cats already on them?

 

[stang17]

I ended up getting a deal on the connection pipes ones through Terry at beefcake racing.

I currently run a PCMTEC canbus flex fuel tune via P1 Tuners and have all emmission monitors ready.

We also dyoned free flow vs the GESI and made the same 786whp SAE 819whp STD.

Just make sure COT protection is turned on within tune and avoid using any type of 2 step like WOT Box etc, and they should hold up fine. We also use the same ones on a 1070 whp hellcat and have held up to 100s of draggy hits, roll race events at Pocono, and test and tune nights at local track.

 

[Fat_Joe]

I ended up getting a deal on the connection pipes ones through Terry at beefcake racing.

I currently run a PCMTEC canbus flex fuel tune via P1 Tuners and have all emmission monitors ready.

We also dyoned free flow vs the GESI and made the same 786whp SAE 819whp STD.

Just make sure COT protection is turned on within tune and avoid using any type of 2 step like WOT Box etc, and they should hold up fine. We also use the same ones on a 1070 whp hellcat and have held up to 100s of draggy hits, roll race events at Pocono, and test and tune nights at local track.

That's crazy! I am glad they held up so well. I will getting these for sure when the time comes. My ultimate goal is to do kooks long tube headers so this works out perfectly as I want to retain the cats if I can. Thanks!

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