Any long term or short term problems with running 1 catalytic converter on one bank and the other bank doesn’t have one on a Y-pipe setup exhaust

[A97obs]

So 4 months in to owning this 99 suburban Im dealing with a missing cat on the driver side down pipe and the 2nd original cat is still on the passenger side down pipe . So someone I know mentioned and noticed all this when I purchased the truck “ said it could lead to engine issues down the line sooner or later …. I just wanted to know if this scenario is actually causing my engine to run maybe richer or leaner or hotter off one of the two sides of the engine bank ?
I don’t know how long the truck had the one cat missing maybe years now …but now 4 months in driving a p0430 code arrived.
It says online a p0430 really would never be a cylinder 1 “drive side” issue and that it is a bad Catalytic converter or o2 sensor issue off the passenger side bank of the engine


Below is a CA emissions exhaust setup for a 99 gmt 400 suburban
My Driver side cat is gone and filled with a 12” flex pipe
Any suggestions if I still have time to add a cat and should they both match in a sense? Should I do both new in a specific type maybe high flow or both just to make them alike , I’m not sure if an oem stock operates differently then a cheap aftermarket ?
Will doing this fix all this time later spare any type of catastrophic failures
Surprisingly the engine runs smooth and sound in every way aside from the missing cat and the sel code

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[movietvet]

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[fancyTBI]

Yes. It can cause drivability issues. Computer knows that a converter should be there. Computer sees anomaly in running conditions and compensates for it.

If it’s a Cali truck, hopefully it’s clean underneath. Just put a whole new Y pipe on. Or you can remove the converters and use a tuner to disable the rear O2 sensors. This might be frowned upon where you live.

 

[RichLo]

Yes, CA emissions needs fully compliant exhaust. You may be able to do a single cat after the Y but it looks like the easiest would be to replace the flex-a-cat with a real one to bring it back to OEM.

 

[KansasOBS]

Nothing constructive from me, but that Mustang exhaust is mint.

 

[A97obs]

Yes, CA emissions needs fully compliant exhaust. You may be able to do a single cat after the Y but it looks like the easiest would be to replace the flex-a-cat with a real one to bring it back to OEM.

It’s extremely clean like it’s the year 99 still under this suv paint and all . I could unbolt the y-pipe with a ratchet literally and likely .

I just wanted to know what’s best option for a replacement cat going back in that section and should the passenger bank have the same type of cat ?

I don’t wanna run junk on the truck but I also wanted too just run a nicer sounding exhaust while I’m at it like true duals to the back , essentially ditching the y-pipe and just doing straight back off each bank after the cat with some borla mufflers midway’

 

[Sean Buick 76]

Do you guys have emissions testing in Michigan? If not then sure just add a straight pipe where the cat was. I don’t run cats on anything, no issues ever.

 

[A97obs]

Yes. It can cause drivability issues. Computer knows that a converter should be there. Computer sees anomaly in running conditions and compensates for it.

If it’s a Cali truck, hopefully it’s clean underneath. Just put a whole new Y pipe on. Or you can remove the converters and use a tuner to disable the rear O2 sensors.

Yes. It can cause drivability issues. Computer knows that a converter should be there. Computer sees anomaly in running conditions and compensates for it.

If it’s a Cali truck, hopefully it’s clean underneath. Just put a whole new Y pipe on. Or you can remove the converters and use a tuner to disable the rear O2 sensors. This might be frowned upon where you live.

When you say tuners you mean like the anti fouler trick on the one and only rear o2 ? Or a pcm tune ?
I would love to just redo my exhaust the way I wanted to without either cats. But wouldn’t that require a federal tune ?

 

[A97obs]

Do you guys have emissions testing in Michigan? If not then sure just add a straight pipe where the cat was. I don’t run cars on anything, no issues ever.

Hell no, we have zero Emissions testing here. We have nothing but crime in Michigan
That’s exactly what I wanna do straight pipe right off of each bank with a set of borla mufflers either dumped before the axles or at 45* out each ass end.

What am I supposed to do with my O2 sensors at that point ? Do I need to run anti-followers the old trick and out of the downstream only ? Or is there a better way to avoid the whole sel light and o2 issue when you delete the cats
Mind you I still have egr air injection pump the whole dam bit.
I wanted to try to get a federal tune and act like I don’t have any of those issues if I deleted all the emissions .
I spoke with black bear performance briefly earlier, try to get an idea for my options “ they’re super sketch with what they wanna do and can or won’t . …you can’t really elaborate on what your wanting to do unless you quote “ own a off-road vehicle “

 

[Sean Buick 76]

100% you keep the two upstream o2s. They are integral to the engine running properly. The rear o2s, I remove the 02 sensor, bag up and take the connector out of the way in case a future owner wants to use them.

The de foulers may trick the down stream 02s however as far as I know only the upstream 02s actually control the tune of the engine. Sometimes they work and other times they don’t. The check engine light will pop up for the downstream 02s not getting the proper readings but that won’t effect anything other than the light popping on.

Blackbear has tuned a bunch of my trucks and I always have them shutoff the downstream 02s in the tune so I can remove the cats without a check engine light. The truck being from Cali doesn’t matter just make the exhaust how you want.