layzie12g

I have a 2003 CL55 that had bad cats. The primary cats collapsed and fell in to the secondaries. My solution was to remove the exhaust from the car and cut open the secondary cats. I gutted all of the catalyst material from all of the catalytic converters. Then the secondary cats were welded back together.

I did this about six months ago and ever since then I have noticed the car has a rough idle. It feels comparable to a cammed Corvette. There is also a hesitation at slow speeds. It has really hurt the driveability of the car. It does sound bad *** at wide open throttle but it is too loud around town. I'm thinking either straight pipe in place of the cats or headers is the only solution. (Mods are in signature)

My questions are:

Have any of you E55 guys removed the catalyst material and experienced something similar?

Would welding in straight pipe instead of letting exhaust dump in to the now open chambers help?

Do you guys with headers notice a rough idle?

SPatykAMG

Not 100% sure if it is causing your rough idle but you should replace them with either a straight pipe or some headers since having the canister there with no material in it causes a pressure pocket and is a disturbance in the system.

shardul

iTrader: (1)

From what I have read sometimes punching out the cats hurts the flow due the the turbulence created within the catalytic Convertor housing

urbamworm

No cats and no stock resonator here and have a normal idle. Perhaps it is tune related doing the change in exhaust (especially since now the o2 sensors aren't reading like they would with a cat in place) without adjusting the tune?

layzie12g

The rear 02s are ignored by Kleemann.

Urbanworm do you mean you gutted your cats like I did or you replaced them with straight pipe?

I do believe the open cavity is causing a disturbance. I should probably get straight pipe welded in.

urbamworm

I have Kleeman headers with no cats (removed) and resonator removed. I could be wrong but I don't see how at idle gutting the cats vs having no cat housing (straight pipe) is going to cause any difference creating a problem at idle.

layzie12g

The logic behind it is that the exhaust is now dumping in to four different open cavitys that used to have a honeycomb material channeling exhaust through them.

Am i really the only person to have cut open the secondaries on these cars to gut the cats?

chawkins2001

Get rid of those gutted cats.

pullejo

Yep. Dump 'em.

No cats, no resonators...no idle issues for me whatsoever.

I do burn through o2 sensors at an abnormally high rate though...gonna fix that.

layzie12g

So my next question is am I the only person on the forum to have done what i have done with the cats? I know there has to he some one else cheap as me who has had the cats fail and gone this route.

pullejo

I've never heard of anyone gutting them before...but it sounds like you're not the first. Hey...we all try and save a buck here and there and there's nothing wrong with that! I've been without cats for two years now though. Had to when I was cheap and hopped in on a group buy for long tube headers (otherwise, I probably wouldn't have bought them!).

That CL needs to breath better - either go back to having regular cats... or spend the $$$ to get rid of them and have some pipes put in.

layzie12g

Ya. That is the next step. Some days I wish I didn't sell my tig. A set of headers should would be nice though. Thanks for the input guys.

layzie12g

So I got this solved. I had straight pipe welded in place of the primary cats and Vibrant race cats in place of the secondaries. This was much easier to say then do. MB exhaust uses different diameter tubing and made fabbing a little difficult. There was a bit of up sizing and down sizing.

It still beat spending $5,000 on a set of factory cats. The smell is gone and the car drives great.

pearlpower

Had 200cel race cats on mine, still failed smog miserably with them and since they did not serve their purpose, I went straight pipe from headers to rear factory exhaust. Loud, but a ton of compliments from strangers.

Afr00t

When you guys say that your cars run fine with no cats no resonator, do u mean no primary cats or no secondary? or no cats at all? The car should drive like crap if primary cats are deleted because the O2 sensor will send faulty readings and mess up the fuel/air intake?

jmb614

Primary oxygen sensors are in front of the primary cats, they care not what is or is not behind them.

Sir-Boost-a-Lot

iTrader: (1)

No cats at all on my CLS, runs beautifully.

Gadget

I would recommend a compression test on the engine to check/verify that it is still mechanically healthy. If it is, you should be able to solve the idle problem.

When you have a cat clog up, the exhaust pressure gets really high and the knock potential really goes through the roof. It is possible that you have damaged one or more pistons due to knock from the high exhaust pressure. I had the same thing happen on one of my vehicles in the past.

When doing the compression test, you will also get a chance to get a good look at the spark plugs.

I doubt your modified exhaust is causing the problem you are having.

G

layzie12g

Bingo Gadget.

This was a year or so ago. That is exactly what happened. Driving the car hard with a bad primary killed the engine. It was wrecked shortly there after by someone else so I guess it worked out for the better.

beisenhauer24

Mine ran all rough when I gutted and still does cause never put on my 3 1/2" down pipes. But I like the idle. Also I noticed turbos don't spin at idle anymore only when hit throttle. It runs 9.81 to 10.23 at track if I hook. So don't care. But mine is s600 v12tt not an 8 and turbos keep it all quiet. Anyone know a cheap way to fix or delete air pump. Mine got loud after deleting them and since no cats at start up I don't need right? And if anyone looking for cheap abc items or factory bose command center with changer and amp. Went to aftermarket unit's. Just message me.And anyone from east coast in pa was trtrying to get group together for some track day's.