Remove primary cats - negative effect?
Thread Starter
Member
Joined: Sep 2010
Posts: 95
Likes: 1
From: Moore, OK
2007 CLK 550
Remove primary cats - negative effect?
Hi all. I tried to search for this answer and had no luck.
If I remove my primaries, whats the worse that can happen until I get a tune?
Will it run like crap?
or
Will I just have the Check Engine light?
Thanks in advance.
Kyle.
If I remove my primaries, whats the worse that can happen until I get a tune?
Will it run like crap?
or
Will I just have the Check Engine light?
Thanks in advance.
Kyle.
Junior Member
Joined: Mar 2011
Posts: 70
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'03 clk 500
From what I know, you'll most definitely get the light until you get a tune to tell the computer otherwise. You also won't be able to take a smog test because your car won't be "ready".
I don't know if you'll run lean/rich though, if that's what you're asking.
I don't know if you'll run lean/rich though, if that's what you're asking.
Thread Starter
Member
Joined: Sep 2010
Posts: 95
Likes: 1
From: Moore, OK
2007 CLK 550
Thanks for the reply. We don't have inspection here anymore. So the smog test issue will be fine.
Yeah, I didn't know if the car would be stumbling and be robbed of any power.
Yeah, I didn't know if the car would be stumbling and be robbed of any power.
Super Member
Joined: Jun 2011
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From: San Diego North County
2015 E400 CAB, 2010 Jeep Compass, 2009 E350 Sedan
I think you MAY lose some Torque in the lower end but thats about it. I doubt you will loose it in HP if you do it will be very minimal.
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Joined: Sep 2007
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Corrolla
Is there a reason why you want to remove the primary? Do you plan to install the headers? Or is it not enough loud for u ? And just read ur message ...all the mods that I have done to the car is more about the looks than performance ( cus I'm broke lol) . I have got my exhaust done and got the C55 AMG airbox w K&N filters installed ..that's it for the performance. Cosmetic, got the H&R springs ( still on the stock shocks) , CF front lip , single fin grille , wrapped my interior w CF , CLK550 taillights w the clear part tinted , some LED for all around and caliper painted ( red) w " white AMG decals" and that was it .
Last edited by M-bENZ; Jul 18, 2012 at 10:25 PM.
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From: A Canadian in Dubai, United Arab Emirates
'05 C200K SS, '05 Kleemann CLK500K, '08 Hummer H3 & '92 Z34 5sp (track car in Canada)
I removed my primaries and secondaries and replaced them with a pair of 100 cell, very low restriction. Car goes for the yearly inspection before the end of the month so we'll see if it passes the sniff this way.
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NO LONGER ACTIVE
Personally, I would not remove them, even if you don't have vehicle emission inspections. First of all, you will get a CEL because the downstream O2 sensors will read a failure and this will have adverse effects on the mixture formation. Second, it is illegal and if you sell the vehicle to a dealer, they will have you sign a form stating that the vehicle has not been modified in this manner. If you won't sign that, they will not accept the vehicle as it violates federal laws.
Honestly, if you want more sound, start by replacing the muffler. If that's not good enough, in order of complexity and cost, first take out the rear resonator (downstream from the two side join at the Y). If that's no good, then remove the "secondary cats", which on your car are really just extra resonators (they contain no catalyst and will have no ill effects on emission or performance). Finally, add headers.
Honestly, if you want more sound, start by replacing the muffler. If that's not good enough, in order of complexity and cost, first take out the rear resonator (downstream from the two side join at the Y). If that's no good, then remove the "secondary cats", which on your car are really just extra resonators (they contain no catalyst and will have no ill effects on emission or performance). Finally, add headers.
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Joined: Jun 2008
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From: Atlanta Metro
2008 clk550 - Navigator - Frontier
I agree with you Rudeney. I have headers and the car makes a nice growl over 2K rpm. I do want it louder at a lower rpm (about 1200 - 1500). I've removed the resonator which did not do much at all, as it is just a straight through pipe with a couple of holes in it. Others have stated that their resonator pipes have many holes (perforated). Mine had only 4 I think. Seemed to be configured as a tuning port.
I will replace the muffler and the perhaps the last quarter of exhaust pipe between the Y pipe and the muffler.
I will replace the muffler and the perhaps the last quarter of exhaust pipe between the Y pipe and the muffler.
Member
Joined: Dec 2008
Posts: 163
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From: Chico, CA
S55K AMG
Downstream o2's do not effect a/f mixtures, only the primary (top o2's) can do that, downstream o2's are strictly for emission/cat monitoring. Though a different model, I removed my primary cats, and love the sound on start up and wot. Just crusing, there is very little audible difference between stock.
