Does straight piping this section (pic attached) will cause me issues?

[sugjavier]

Hey guys, quick question: Does cutting out the boxed area (in the diagram attached) cause me any issues?

I've been having trouble with the stupid vibration/rattle noise and my mechanic have changed gaskets and looked for exhaust leaks to fix the issue multiple times. I have also tried other shops to tell me what's wrong and they said that the cats are bad.


Anyways, my mechanic said that he can cut out the boxed area and weld a straight pipe in place and that should take care of my noise issue instead of me buying the OEM cat system which is like over $1k (f that). I also don't feel like buying aftermarket cats since I've heard they only last a couple years anyways.

I know that it might also pop the PO420 codes like I had before (it was fixed by replacing the rear o2 sensor) but I can just clear that code out with my scanner thing OR leave it alone lol.
I also know that straight piping it will make like a more throaty sound but since I have the muffler still, it shouldn't be like obnoxiously loud is it?

Oh and don't worry about passing the tests and stuff, I live in Michigan and I don't think we have them lol

 

[cashmoney]

Nope. Will just through a constant CEL light. There's a thread a few lines down from this one about how to build your own 02 simulator to get rid of that light.

 

[gamefreakgc]

The rear O2 sensor is in that boxed area, which is a sure fire way to ruin your fuel economy and throw a constant check engine light.

I suppose you could run a simulator for the rear O2 sensor and straight pipe it, but I have no experience on whether or not that will affect how the engine runs.

 

[jeremyc74]

The rear O2 sensor is in that boxed area, which is a sure fire way to ruin your fuel economy and throw a constant check engine light.

I suppose you could run a simulator for the rear O2 sensor and straight pipe it, but I have no experience on whether or not that will affect how the engine runs.

Rear O2 won't hurt fuel economy, only the front. The ECU can't calculate fuel trims using data from behind the converter. The only purpose for the rear sensor is the make sure the converter is working.

 

[sugjavier]

Rear O2 won't hurt fuel economy, only the front. The ECU can't calculate fuel trims using data from behind the converter. The only purpose for the rear sensor is the make sure the converter is working.

So I should be okay right? I mean I'll let my mechanic know to not cut off the rear o2 sensor lol and I can do the simulator later.

 

[98OzarksRunner]

So I should be okay right? I mean I'll let my mechanic know to not cut off the rear o2 sensor lol and I can do the simulator later.

Other than that federal offense thing for modifying the smog system. olice:

 

[jeremyc74]

So I should be okay right? I mean I'll let my mechanic know to not cut off the rear o2 sensor lol and I can do the simulator later.

It's a half assed fix, but it should run ok.

Other than that federal offense thing for modifying the smog system. olice:

Exactly. Although I'm not sure they care too much about that in MI. CA and NY and you'd be looking at a pretty healthy fine if you got caught.

 

[3bears]

the feds are gonna come after you now that you posted on the internet your gonna do something against fed law
forget food stamp or unemployment fraud ,
they will send a crew after you and tarnish you for life for getting rid of that cat.
might mean serious jail time