Secondary Cat failure

ASPEC135i · 04-18-2015, 09:24 AM

One of my secondary cats are rattling like a little b*tch!

Had the 1er on the lift and pinpointed out that the rattle was from INSIDE one of the secondary cats.

Never have heard / read about this issue before on here or e90post.

However, a quick google search indicates that this is a textbook symptom when a cat fails. The ceramic inside is being knocked around.

I've been running catless DP, with stock n54 mids (with secondary cats), and PE (with y-pipe) for 50,000+ kms.

It seems that my fuel economy has been slightly effected as well. It's consuming slightly more fuel.

Just wondering if anyone else went through a similar situation?

Before this happened, I've been very happy with my exhaust setup. Now I'm forced with either a) purchase n55 midpipe b) simply straight pipe it (and if so, I'm debating between t304 vs t409 stainless steel to be tig welded on)

Also, does anyone have the following exhaust setup? I've wondering if it will be too loud or create a drone: Catless DP + no secondary cats + y-pipe + PE.

Cavpilot2k · 04-18-2015, 10:35 AM

I'm close to that setup except I still have stock DP. My setup is loud on cold start and my GF finds it a little obnoxious, but I love it. I've heard that taking that setup to a full catless setup creates rasp and you'd want resonators.
But that is second hand info.

Kgolf31 · 04-18-2015, 11:24 AM

What else do you expect when you're asking your secondary cats to handle a primary cat job?

They are going to fail. Go hi-flow race cats

04-18-2015, 09:24 AM	#1
ASPEC135i Lieutenant 16 Rep 566 Posts Drives: sideways always Join Date: Oct 2012 Location: location, location iTrader: (0)	Secondary Cat failure - Rattle One of my secondary cats are rattling like a little b*tch! Had the 1er on the lift and pinpointed out that the rattle was from INSIDE one of the secondary cats. Never have heard / read about this issue before on here or e90post. However, a quick google search indicates that this is a textbook symptom when a cat fails. The ceramic inside is being knocked around. I've been running catless DP, with stock n54 mids (with secondary cats), and PE (with y-pipe) for 50,000+ kms. It seems that my fuel economy has been slightly effected as well. It's consuming slightly more fuel. Just wondering if anyone else went through a similar situation? Before this happened, I've been very happy with my exhaust setup. Now I'm forced with either a) purchase n55 midpipe b) simply straight pipe it (and if so, I'm debating between t304 vs t409 stainless steel to be tig welded on) Also, does anyone have the following exhaust setup? I've wondering if it will be too loud or create a drone: Catless DP + no secondary cats + y-pipe + PE.
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04-18-2015, 10:35 AM	#2
Cavpilot2k Chief Warrant Officer 1025 Rep 1,638 Posts Drives: like a damn lunatic Join Date: Feb 2012 Location: Boston iTrader: (0)	I'm close to that setup except I still have stock DP. My setup is loud on cold start and my GF finds it a little obnoxious, but I love it. I've heard that taking that setup to a full catless setup creates rasp and you'd want resonators. But that is second hand info. __________________ "Prius" is Latin for Eunuch. "Hrothgar": 2012 135i: 6MT M-Sport, BSM/Blk; Nav, Premium, Convenience, HK Dinan Stage 2 +PPK /// BMW PE /// VRSF CP /// K&N /// Koni Sports /// RSFB Inserts /// MPS4S 225/255 /// Other Stuff
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04-18-2015, 11:24 AM	#3
Kgolf31 Brigadier General 460 Rep 4,531 Posts Drives: 2007 Z4MC, 2012 128i Join Date: Sep 2008 Location: Ohio iTrader: (4)	What else do you expect when you're asking your secondary cats to handle a primary cat job? They are going to fail. Go hi-flow race cats
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