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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > Catless downpipes but keep orignal secondary cats



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      12-13-2012, 02:19 AM   #23
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Quote:
Originally Posted by nailer335 View Post
I've got catless DPs with stock midpipes and stock catback. On a true cold start in my garage (with the garage door open obviously ) I smell gas easily, because the secondaries haven't warmed up yet. Once they're warm, they reduce the gas smell significantly- you can't smell it from inside the car unless windows are all the way down and you're stopped at a light. Even then I rarely ever notice the smell and it is extremely faint.
This is true...

Faint smell with cold starts....no smell once warmed up
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      02-07-2013, 06:25 AM   #24
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Any updates? Has anyone attempted to pass with this set up in california.
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      02-07-2013, 10:22 AM   #25
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Originally Posted by 335iJWC View Post
Any updates? Has anyone attempted to pass with this set up in california.
Its doubtful you would pass a sniffer test with catless downpipes especially in a place like California

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      02-07-2013, 12:22 PM   #26
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Originally Posted by RimasRS View Post
The main problem is that secondary cats will clog up. Because primary cats filtering and after they becoming worm/hot burning all kind of sh*t. If you will go just with secondary cats they will not last long...
You're not the first guy I've seen say this, but I don't recall seeing any threads about cooked secondaries. A lot of guys run this setup, is this really a verified risk?

And yeah, I should've done this before posting the question, but on the move today and just wanted to get the question out there.
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      02-07-2013, 12:24 PM   #27
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I have catless downpipes with the factory midpipes, but I want to remove my secondary cats. I have yet to find a shop willing to do it, though.
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      02-07-2013, 12:25 PM   #28
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Originally Posted by 335iJWC View Post
Any updates? Has anyone attempted to pass with this set up in california.
I think California is getting rid of the sniffer test for 2013.
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      02-07-2013, 04:15 PM   #29
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Quote:
Originally Posted by mikead_99 View Post
You're not the first guy I've seen say this, but I don't recall seeing any threads about cooked secondaries. A lot of guys run this setup, is this really a verified risk?

And yeah, I should've done this before posting the question, but on the move today and just wanted to get the question out there.
I know this because I have other cars like 320d which had both cats primary and secondary I removed secondary because it was clogged (checked) this was suggested by workshop who is dealing with turbo chargers and they say that primary cat burn cleans by heat secondary catching everything else what's left from primary also they say that clogged cats can cause turbo damage.
Believe it or not but that is what I saw heard and I think it is logical
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      02-07-2013, 05:00 PM   #30
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Quote:
Originally Posted by RimasRS View Post
I know this because I have other cars like 320d which had both cats primary and secondary I removed secondary because it was clogged (checked) this was suggested by workshop who is dealing with turbo chargers and they say that primary cat burn cleans by heat secondary catching everything else what's left from primary also they say that clogged cats can cause turbo damage.
Believe it or not but that is what I saw heard and I think it is logical
No, I agree it's logical, just looking for instances on this platform....well, the gasoline burning variants. These cars have been around long enough now that somebody would have had to seen this if it is a high probability risk.
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      02-07-2013, 05:02 PM   #31
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Originally Posted by Wesley Crusher View Post
I think California is getting rid of the sniffer test for 2013.
They are. My good buddy just passed his emissions exam so now he is certified. He said there is no way I would pass with catless with the sniffer test. And as far as the OBD2 only test for 2013, not all places are going to implement it at once... gotta find a place that does it.
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      02-08-2013, 05:15 AM   #32
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Quote:
Originally Posted by mikead_99 View Post
No, I agree it's logical, just looking for instances on this platform....well, the gasoline burning variants. These cars have been around long enough now that somebody would have had to seen this if it is a high probability risk.
Best thing catted after market downpipes and no secondary cats... Though I know this is expensive.
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      02-10-2013, 12:01 AM   #33
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Originally Posted by eric@helix View Post
I have never seen the catless dp/catted tail section in the shop. I'm really curious as to the smell level compared to fully catless. Anyone done both? Comments?
I got this setup installed in your shop two weeks ago
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      06-07-2018, 06:34 PM   #34
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Quote:
Originally Posted by Jeff@TopGearSolutions View Post
There is a slight difference in smell from full catless to secondary cats still installed. When I had just catless downpipes and I still had secondary cats the smell was barely noticeable but still apparent compared to fully catted.

Fully catless to me is quite obnoxious. I've had a few cars with full catless modifications and I dont think I will ever go back to it. I dont miss pulling up to lights and catching a wiff of fumes.
Help me understand this better. With windows down at stop light and just secondary cats, how bad is the smell?
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      06-08-2018, 12:05 AM   #35
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Quote:
Originally Posted by taranfx View Post
Help me understand this better. With windows down at stop light and just secondary cats, how bad is the smell?
Smell is none at all - sitting at a light car idling. The only time I smell my car is when I first start in garage. I've had full catless cars / trucks and you typically get smells...which I have NO problem with. I grew up with 60's cars and such - so I have a different tolerance. ALL that being said, my e90 with dp's and 2nd cats - has no real smell. Especially compared to past truly catless cars. I plan to remove my 2nd cats - soon. I have no fear about the smells...from what I understand - e92 cars HAVE NO 2nd cats only us e90 guys do.
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      06-08-2018, 03:52 AM   #36
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Originally Posted by bluemonstr View Post
Smell is none at all - sitting at a light car idling. The only time I smell my car is when I first start in garage. I've had full catless cars / trucks and you typically get smells...which I have NO problem with. I grew up with 60's cars and such - so I have a different tolerance. ALL that being said, my e90 with dp's and 2nd cats - has no real smell. Especially compared to past truly catless cars. I plan to remove my 2nd cats - soon. I have no fear about the smells...from what I understand - e92 cars HAVE NO 2nd cats only us e90 guys do.
Perfect. Exactly the response I was looking for. I've gone full catless with N55 in the past and I couldnt take it for a day. I went catted downpipe on n55 and I loved the gains. Just wanted to make sure its similar. Sounds like it is.
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      06-08-2018, 04:05 AM   #37
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Quote:
Originally Posted by bluemonstr View Post
Smell is none at all - sitting at a light car idling. The only time I smell my car is when I first start in garage. I've had full catless cars / trucks and you typically get smells...which I have NO problem with. I grew up with 60's cars and such - so I have a different tolerance. ALL that being said, my e90 with dp's and 2nd cats - has no real smell. Especially compared to past truly catless cars. I plan to remove my 2nd cats - soon. I have no fear about the smells...from what I understand - e92 cars HAVE NO 2nd cats only us e90 guys do.
Difference between us e92 and european e92? My 07 335i e92 have secondary cats and I have catless downpipes but can still pass emission test here in Sweden.

No bad exhaust smelling here either, smells good with some E85 in the fuel
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      06-08-2018, 12:29 PM   #38
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European E92 335i here with catless downpipes, all the rest is stock. You can definitely smell that the main cats are gone, also when going WOT the car behind you WILL smell it.
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      06-09-2018, 10:46 PM   #39
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European E92 335i here with catless downpipes, all the rest is stock. You can definitely smell that the main cats are gone, also when going WOT the car behind you WILL smell it.
Agreed. Catless DPs with secondary cats still stinks. Running E60 makes a big difference though. If, for some reason, I could not longer run any E and had to switch back to 93 octane, the stock DPs would likely get reinstalled.
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      06-11-2018, 08:35 PM   #40
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Originally Posted by FCobra94 View Post
Agreed. Catless DPs with secondary cats still stinks. Running E60 makes a big difference though. If, for some reason, I could not longer run any E and had to switch back to 93 octane, the stock DPs would likely get reinstalled.
Did you mean smell is bad with e60? I'm not plannign to run any ethanol mix. How bad was smell idling on a stop light (once cats are warm).
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      06-12-2018, 06:53 PM   #41
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Quote:
Originally Posted by taranfx View Post
Did you mean smell is bad with e60? I'm not plannign to run any ethanol mix. How bad was smell idling on a stop light (once cats are warm).
Running higher E content - the smell is cleaner (upon first start up). I have noticed that too. I typically run about 6 gals of E85 into my tank (I guess that is about E40 or so).

There is MORE smell w/out the E85 - that is what he was saying. However, all that being said...again - w/second cats it's minimal and for me - non issue.
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      06-12-2018, 09:29 PM   #42
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Quote:
Originally Posted by taranfx View Post
Did you mean smell is bad with e60? I'm not plannign to run any ethanol mix. How bad was smell idling on a stop light (once cats are warm).
No, smell with E60 is "sweet smelling" and makes the catless DPs tolerable w/ secondary cats in place.

Smell on 93 octane when cats are warm = if you stand behind the car, every ~3rd puff is stinky smelling given that the secondary cats can't do enough on their own to convert all the hydrocarbons, etc. If I had to describe the smell, it almost smells like burnt hair/nasty hair salon chemcals. I read an article once on why that is, but unfortunately can't find the link at the moment.
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