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Discussion Starter #1
So the car sounds like crap when it's idling because the coverter is rattling like crazy.

I don't have emissions inspections, so do I even need this anymore? Will it screw anything up?

I don't want the service engine soon light coming on and I don't want the car sounding like a muscle car either.
 

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1994 Cadillac Eldorado Touring Coupe
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821 Posts
It won't hurt anything but politicians feelings if you pull it off. If your car would have been a 96 or newer though, you would have thrown a P0420 code which is easily rectified by a simple hack. If you try it let us know how much louder the car gets.
 

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Cadillac Technician
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11,051 Posts
Apart from it being a violation of federal law and that it will drastically increase the hydrocarbons, carbon monoxide, and oxides of nitrogen entering the atmosphere contributing to ground level ozone, smog, and poor air quality in your area no, you should be fine to put a straight pipe on it.
 

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1993 Eldorado, 4.9L, 200k miles
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273 Posts
The exhaust on my '93 Eldorado 4.9L cracked wide open at the Catalytic Converter's exhaust port such that the pipe was fully open at the Cat's. I noticed a significant decrease in performance likely due to the untuned exhaust flow....it simply felt like the engine had asthma....it was very annoying. Changing the backpressue w/ a straight pipe may do the same.

Btw, how do you know the internal's of the Cat are the source of the rattle? Before changing the Catalytic converter...inspect the "rubber band" hangers that are located just behind the Cat...if the rubber bands are weak or missing, the exhaust pipe may rattle on the cross brace (also located just behind the Cat) and make a sound like loose internals in the Cat...inspect it w/ the engine running at idle. Due to my poor repair of the Cat's exhaust connection on my car, I have the rattle and it occurs only at idle also.
 

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Cadillac Technician
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It may run differently and not necessarily in a good way.
The CEL will not come on as that year did not have catalyst monitoring equipment.
I'd agree that your issue should be pinpointed accurately and a decision made based on that.
There are a lot of affordable options to keep the vehicle running as it was designed and not choke your neighbors or the guy behind you on the highway.
 

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1992 Seville
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323 Posts
Just a thought - The EGR valve on you car requires a positive back pressure from the exhaust system to work. If the required back pressure is calibrated to include what ever drag the catalytic converter imposes on the exhaust flow then you could have some problems.
 

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1994 Cadillac Eldorado Touring Coupe
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821 Posts
Removing the cat won't cause any "back pressure calibration" problems. Just will make the car a slight bit noisier and emit poisonous gas. You may even pick up 1 or 2 HP removing it.
 

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Cadillac Seville STS 2003 47000 miles
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128 Posts
Just about every rattling cat converter issue that I have dealt with was due to the heat shield around the converter coming loose. If you don't want to replace the converter then go to any hardware store and pick up two 6 inch stove pipe clamps. Place the clamps around the heat shield and tighten them up. No more rattles.
 

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96 Eldorado
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283 Posts
Just about every rattling cat converter issue that I have dealt with was due to the heat shield around the converter coming loose. If you don't want to replace the converter then go to any hardware store and pick up two 6 inch stove pipe clamps. Place the clamps around the heat shield and tighten them up. No more rattles.
This is a common problem for cars for all makes, The spot welds rusting loose an causing a very irritating rattle. RENEW82 mentioned the easy fix that is the smartest fix. Large diameter hose stanless hose clamps piggy backed together and tightend around the whole body shield if the converter. Its important to have the heat shield on the converter because its a fire hazard without the tin shield. Keeping the converter in place is the better way. Although, I do believe a WOT hp rating would increase more than a coulple of hp. I would say somewhere between 5-10hp. Plus you would get a deeper tone in the exhuast tone Because the converter definately helps muffle some before the exhaust reaches the mufflers. An OBD-1 system would have no adverse affects due to eliminating the converter. The emmisions may still pass the federal sniffer test but would fail only because the converter is not in place. Most cars are capible of passing a federal emmissions standard for that vehilce spec without a cat due to refined engine management controls. Technically, the passenger car without a cat is illeagel in all fifty states.
 

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1994 Cadillac Eldorado Touring Coupe
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821 Posts
This thread has me wanting to remove mine. I may do so and record before & after exhaust tones. I'll let you all know if I decide to do it.
 

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1997 STS, 1991 Chevy RC w/500 CAD
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115 Posts
According to Little Mike on the caddyinfo site:

removal of cat netted 6hp (tested with gtech).


In my experience on previously owned vehicles, removing the cat will certainly increase the sound levels.
 
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