Running open downpipes

Gustavor

Lurker
Feb 1, 2018
10
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2007 BMW 335i
Those of you running on open downpipes on stock twins, did it do any harm?
 

Aaron

Lieutenant
Nov 3, 2016
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Colorado
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Silver 2013 335is 6MT
I can't imagine how it'd do any harm, however there is a risk of carbon monoxide poisoning when you're not moving.

But there's no real benefit from it either.
 

Gustavor

Lurker
Feb 1, 2018
10
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2007 BMW 335i
I can't imagine how it'd do any harm, however there is a risk of carbon monoxide poisoning when you're not moving.

But there's no real benefit from it either.
So nothing could happen to the car?
 
Dec 27, 2016
134
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2010 e90 335i
I ran open downpipes for months on stock turbos as i sold my exhaust and couldnt pick a new setup. Loud as hell, sounds cool, zero issues, and smells good lol

 
Dec 27, 2016
134
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2010 e90 335i
I read somewhere about how it makes bank 2 run lean and I also got a check engine light not tol long ago

I'm not going to tell you that's not possible because anything can happen. But my logs were perfect. Also note i wasnt running OTS maps, always custom maps
 

veer90

Captain
Nov 16, 2016
1,000
762
25
West Nyack, NY
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e90 335i 6MT
I ran open downpipes for a week once for shits and giggles. Other than making my ears bleed, the fuel trims got wonky because the post-cat O2s are too close to the end of the downpipe / ambient air. I got mixture control and "bank 1-2 O2 sensors switched" fault codes intermittently.

Wouldn't recommend it.
 

Gustavor

Lurker
Feb 1, 2018
10
1
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2007 BMW 335i
I ran open downpipes for a week once for shits and giggles. Other than making my ears bleed, the fuel trims got wonky because the post-cat O2s are too close to the end of the downpipe / ambient air. I got mixture control and "bank 1-2 O2 sensors switched" fault codes intermittently.

Wouldn't recommend it.
Yeah that's what's happening right now
 

Jon1998

Lurker
Dec 1, 2017
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I ran open downpipes for a week once for shits and giggles. Other than making my ears bleed, the fuel trims got wonky because the post-cat O2s are too close to the end of the downpipe / ambient air. I got mixture control and "bank 1-2 O2 sensors switched" fault codes intermittently.

Wouldn't recommend it.

im open down pipe, single turbo doc race kit. the car does not like it. Brand new Ntk’s and new rear 02s. I get mixture control codes and also system check codes, as well as fuel trims leaning out. Safe to say no exhaust causing this?
 

SD Garage

Private
Jul 4, 2017
26
13
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e92
One of our guys is running downpipe out but has attachments that point the exhaust gases straight towards the ground. No issues.