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E46 M3 (2001-2006) Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006.


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Old Thu, Feb-09-2017, 02:37:56 PM   #1
burningchrome
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Default Bad cats. What to do?

Well, my bank 2 catalytic converter is bad. Fortunately, I'm in a state that DGAF about emissions, so I don't have to get it fixed immediately, but I might as well upgrade it eventually.

What is the most cost effective upgrade to go cat-less? Euro headers and straight section 1? aFe? Would doing the headers without replacing section 2 and the muffler be counter-productive?

Thanks for your input.
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Old Thu, Feb-09-2017, 03:05:38 PM   #2
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Default Re: Bad cats. What to do?

Your correct the most cost effective is euro headers with your stock section 1. It will bolt right up, keep on mind you will need new gaskets.

You will notice the difference so I say it's worth doing it, even if you don't want to go full exhaust
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Old Thu, Feb-09-2017, 03:51:57 PM   #3
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Default Re: Bad cats. What to do?

Euro headers would be the cheapest option. It's a direct bolt on with OEM fitment. As stated above, you just need new gaskets. They usually go for around 500-600.


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Old Thu, Feb-09-2017, 04:33:02 PM   #4
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Default Bad cats. What to do?

Doing headers without section two and muffler is not at all counter productive imo. I would recommend either euro headers/euro section 1 (with cats) or aftermarket headers/catted section one. Aftermarket will be louder/possibly make more power but euro will for sure fit well
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Old Thu, Feb-09-2017, 05:00:21 PM   #5
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Default Re: Bad cats. What to do?

Go euro and never look back!
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Old Thu, Feb-09-2017, 11:31:47 PM   #6
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Default Re: Bad cats. What to do?

So if I go euro, what do I do with the post-cat O2 sensors?
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Old Fri, Feb-10-2017, 01:23:54 AM   #7
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Default Re: Bad cats. What to do?

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Originally Posted by burningchrome View Post
So if I go euro, what do I do with the post-cat O2 sensors?
You can get them coded out, or weld 02 bungs into your section 1 and add an 02 simulator. If you go aftermarket, they have 02 bungs for your post cat sensors.
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Old Fri, Feb-10-2017, 06:09:01 PM   #8
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Default Re: Bad cats. What to do?

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Originally Posted by mdavidm3 View Post
You can get them coded out, or weld 02 bungs into your section 1 and add an 02 simulator. If you go aftermarket, they have 02 bungs for your post cat sensors.
That depends if he goes euro header and euro cat or just euro header.

If he goes euro header alone, then the above applies. If he goes euro header and euro cat, then the post cat 02's will go directly into the euro cats.
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Old Wed, Feb-22-2017, 03:24:48 AM   #9
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Default Re: Bad cats. What to do?

I'm surprised this thread hasn't gotten more action with the age/mileage of the stock cats. I'd think many cars are starting to throw catalyst efficiency codes with a CEL.

My current car has this very problem and the car I'm about to buy does also.

Here's the problem - in CA they don't do sniffer tests BUT they do plug the into the car's computer and do a visual. A CEL is automatic fail as is the rear 02s being coded out. The car's computer/systems need to be a fully ready state. I'd expect most every other state to be identical.

So - short of Euro cats what are you guys doing to both not have a CEL AND not have your rear 02s turned off?

I'm intrigued by options but I'm concerned about these triggering the CEL:

- Fabspeed 200 cell midpipe ($1200)
- AA 100 cell midpipe ($900)
- Status 200 cell midpipe ($700)
- SS 200 cell midpipe ($2800)

Also - it should be noted that the OE Euro section 1 retails for $2755 - I wonder if this can still be bought new? Further, it looks like (according to ECS' site) that BMW now offers reman US headers/cats for $2900/pair.

Finally - there's always the 'build your own' option. The thing is is that I want quality and zero issues with CELs.

Thoughts?

Edit - what about 02 foulers for the rear 02s?
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Old Wed, Feb-22-2017, 05:59:24 AM   #10
djjvr
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Default Re: Bad cats. What to do?

Quote:
Originally Posted by EricSMG View Post
I'm surprised this thread hasn't gotten more action with the age/mileage of the stock cats. I'd think many cars are starting to throw catalyst efficiency codes with a CEL.

My current car has this very problem and the car I'm about to buy does also.

Here's the problem - in CA they don't do sniffer tests BUT they do plug the into the car's computer and do a visual. A CEL is automatic fail as is the rear 02s being coded out. The car's computer/systems need to be a fully ready state. I'd expect most every other state to be identical.

So - short of Euro cats what are you guys doing to both not have a CEL AND not have your rear 02s turned off?

I'm intrigued by options but I'm concerned about these triggering the CEL:

- Fabspeed 200 cell midpipe ($1200)
- AA 100 cell midpipe ($900)
- Status 200 cell midpipe ($700)
- SS 200 cell midpipe ($2800)

Also - it should be noted that the OE Euro section 1 retails for $2755 - I wonder if this can still be bought new? Further, it looks like (according to ECS' site) that BMW now offers reman US headers/cats for $2900/pair.

Finally - there's always the 'build your own' option. The thing is is that I want quality and zero issues with CELs.

Thoughts?

Edit - what about 02 foulers for the rear 02s?
Plenty of people in CA pass smog with the Euro cats. They also won't throw a CEL for cat deficiency if they are still in good shape. Worst case code your post cat O2s into ready but not monitoring.

As for the pricing, just find a low mileage set online and save yourself some money.
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Discussing Comprehensive CSL Intake Thread in the E46 M3 (2001-2006) Forum - Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006. at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)