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Discussion Starter #1
Just as a cross-check on my own troubleshooting, what are the classic symptoms of a clogged CAT converter?

Grazie muchissimo for your assistance.
 

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1966-2013
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Stalling at idle, loss of power, the need to rev the engine a bit more to get rolling, quieter exhaust rumble, perhaps the sound of hissing air when you rap the throttle, and slow throttle response at idle among other things.
 

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Discussion Starter #3
Yep, sounds like that, acts like that! And I thought I had fuel delivery issues.
When I heard the hissing sound from under the car this afternoon, it all came together for me. Lumpy idle, an occasional stumble, straining to accelerate, and the backpressure of the exhaust blowing out every gasket it can!

The heck of it is, the car doesn't have 60K miles on it! And it shows no codes off the ECU. Nothing... nada. We've had this Spider for nearly four years now, and used nothing but Chevron 93 octane. The engine never gave any problems with rich running that I can recall, either. I wonder what happened?

Now, to find a replacement cat converter that bolts up for south of $590...

I've seen Magnaflows advertised for "1982-94 Spiders", in the realm of $300, but does anyone know for sure if they'll fit correctly? The doggone fitting for the O2 sensor is on top of the inlet, with the floorpan blocking the apparent installation of an O2 sensor! Am I right here? Has anyone used this aftermarket cat successfully on their Spider?

I see that Simon lists the new Magnaflow cat available for up to 1989 models only. :(
 

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1966-2013
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A lean mixture can burn one up too. (you know, like a false air leak at the intake manifold rubbers)

Actually anything not close to stoich for extended amounts of time can put the bake into it. (like lots of short hops with a shutdown and startup at each one blowing the extra startup enrichment in there every time among other scenarios)

If you can't get the O2 sensor out with the headpipe in place, it's not too big a deal to drop it and pull it once things are out over there on the floor. Just make sure you disconnect the O2 wires fitst of course.

Dunno on fit/availability of S4 converters, though with a creative muffler shop, chances are high you could get a generic one in there.
 

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Discussion Starter #5
Thanks for the help, OK? I appreciate your comments. The cat is definitely discolored - it's toast.

I'll continue shopping around. But I just want to ensure the mixture's on target before I ruin a new one. I'm going to check again for any codes in the ECU.
 

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1966-2013
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If you click the link in my sig, it'll take you to an L-jetronic test-n-tune page.

While you're on Motronic, the information regarding the O2 sensor, and more particularly how to test it, still applies.

If it doesn't test correctly then your ECU will revert to a different 'safe default' mixture that usually runs in the more than a little rich range, (closer to 12.x:1 than the 14.7:1 stoich), and it will likely never go into closed loop so that fat mixture is what you end up running all the time.

If nothing else, it'll at least let you know if your sensor is still worth beans.
 

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Discussion Starter #7
OK- I'll look it over. Thanks again.

I'm beginning to think the O2 sensor went, then led to the coking up of the converter. It all happened fairly quickly, like over a period of several weeks.

Not taking any chances, I'm replacing the sensor also.
 

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Now, to find a replacement cat converter that bolts up for south of $590...
Drive (or tow...) your car to any decent muffler shop (the 'best' ones IMO are usually in the 'tough' side of an old town) and they can cut out the old catalytic converter and weld in a replacement unit that'll probably flow better than the original one. Expect a cost of ~$75 - $100 for the cat plus $25 - $50 for the labor.

Replace the O2 sensor, too. You can buy the whole sensor with wires for $$$ or a replacement that you re-use the current wires for $$.
 

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OK- I'll look it over. Thanks again.

I'm beginning to think the O2 sensor went, then led to the coking up of the converter. It all happened fairly quickly, like over a period of several weeks.

Not taking any chances, I'm replacing the sensor also.
Hi Dave;

Yea I just went through the same stuff with my CAT/O2...check out the link.

(http://www.alfabb.com/bb/forums/showthread.php?t=48827)

As Tifosi says, it's pretty easy to drop the front pipe and get at that sensor. Heck it was only 4 bolts from the manifold and three bolts aft of the CAT. I even ramrodded the baffles in the CAT to clean it out. Mine is an original with over 100K on it. :)
 

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Is there anyone that just sells a cat removal pipe? I'd like to just have a replacement pipe that I can put in place of the cat instead of gutting it.
 

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Discussion Starter #12
Oh yeah, I remember those kind of muffler shops. Back in my hot rod Ford Cortina GT days, I had a custom system made up just the way I'd imagined it!
I may seriously look at that route, Eric. After all, the ECU doesn't know nor care what kind of cat converter is hangin' under the car. But the O2 sensor without a doubt gets replaced! Maybe even the center muffler section (the rear tailpipe is new).

I am going to call Centerline and IAP tomorrow about that vertically mounted O2 sensor. From what I see under my Spider, it won't work! I mean sure, you can install it, but I don't think the top of the sensor will clear the floorpan once you bolt everything together. Now that's a problem. The threaded boss should be on the side of the pipe, like the OEM cat design.

These days, litigation costs and liability being what they are in the USA, I doubt any business who watches their backside would remove a cat and replace it with a section of pipe. It's real, real illegal!

Thanks for the feedback, fellows. I appreciate your time and opinions.
 
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