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Discussion Starter #1 (Edited)
OK. Last night I completely re-assembled things on my '89 Graduate after replacing water pump, radiator, shroud, belts and hoses.

I hooked everything up as I disassembled it and refilled the coolant per instruction on the BB. The whole time I had a feeling I was forgetting something.

I started her up and she was very smoky and very rough. Needed my foot on the gas a bit. I just figured it was because everything was apart for a couple of weeks and it would clear up.

After about a minute the smoke was getting worse so I backed her out of garage and into driveway. Still weak and sputtering.

After another minute or two my teen aged son comes to me and says "Is there supposed to be flames coming from the tailpipe?"!!

I immediately turned off the motor and got out while other son and wifey ran to get fire extinguishers and hose.

Smoke was really bad from underneath now and when I looked underneath the center muffler (which has holes and like the rear muffler needs replaced) was glowing RED HOT!!

I seriously thought we were about to have a Car-B-Q and waited at the ready with hose, fire extinguishers and finger on the 911 button of my phone.

In a couple of minutes the glowing and smoking stopped and I was able to exhale.

The bi!7# of it was that the motor hadn't even warmed to operating temp yet.

As I was checking things over in and around for any damage I finally came across the wiring harness for the Bosch intake at the air filter, which was still disconnected:cursing:!!

I reconnected it and let it cool further. I got it to start and within a few seconds it seemed to be running relatively smooth. I shut it down and pushed it back into the garage once it was sufficiently cooled and called it a night.

Is there a chance I could have done any permanent damage to any components other than the mufflers (which need replaced anyway)? My biggest concern is for the cat. Is there a way I can test things out with the cat? What else should I be looking for??

Thanks in advance-M5
 

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With the AFM disconnected, the engine will run very rough. I suspect incomplete combustion, resulting in a rich mixture in the exhaust, caused your catalytic converter to overheat and that is what was red hot. The CAT may be toast but I doubt you did any other signficant damage.
 

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most likely the excessively rich mixture was burning in the CAT. It is more than likely melted and ruined. Otherwise you are probably ok.
 

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Discussion Starter #4
That makes me feel a little better.

Is there a way I can test the cat?

I went and check under the car and the glow was coming from the center muffler which is towards the rear wheels. The rear muffler had flames shooting out of it.

The cat is still intact. The two mufflers were already rusted through in spots. I did find some strange debris in the driveway where the car was. It was the usual pieces of rusted metal, along with pieces of what looks like steel wool, but is more fiber glass like. There is also some chunks of what reminds me of asbestos (I helped my dad cut asbestos shingles for our house back in the days when we still used the stuff.

I can post a pic of the stuff if you like.

Thanks for taking the time. I sure hope my cat isn't toast. I imagine they are quite expensive.

M-5
 

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Maybe a hundred bucks but, being in Florida, do you even need a Cat? You might just need a length of pipe.
 

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Discussion Starter #6 (Edited)
Maybe a hundred bucks but, being in Florida, do you even need a Cat? You might just need a length of pipe.
Will not having a cat (or having a toasted one) send improper data to the ECM or PCM? I'm not sure how much my '89 spider relies on the cat.

Thanks for the suggestion. That bears looking into.

M-5
 

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There is also some chunks of what reminds me of asbestos (I helped my dad cut asbestos shingles for our house back in the days when we still used the stuff.
That is the innards of your cat converter and mufflers that melted and shot out the rear.

Worst case you melted the cat matrix and plugged up the exhaust. Sounds like the mufflers were already shot anyway so may not be too much of a loss. Personally I'd take it as an opportunity to get the exhaust replaced.

The cat doesn't affect running (as long as it's not plugged up) but even if you don't have state inspections it's illegal to completely remove it. So no legit muffler shop will do so for you.
 

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Miami, the O2 sensor is what sends a signal to the ECU and helps to set your mixture while running, and it is in the downpipe just before the CAT. If that was damaged (O2 sensor) you would have strange running issues after the warm up cycle completes. I'm thinking that the resonator is where the rich mixture was reacting, but since you didn't see if the CAT was glowing, who knows if the CAT was damaged. You would find out at emissions testing, or if they don't have that in your county, take it to a shop and ask for an emissions test. Or if it's suddenly gutless and you can't accelerate worth a ****, your CAT indeed melted and the honeycomb material inside broke off and clogged up the works.

I just bought a 'stinger' from Centerline to replace the crappy rusty muffler, and I love the exhaust note. $70 or so. I also found a magnaflow CAT with downpipe for around $300 with shipping from Summit Racing, but you can get just the CAT welded in and it will be just fine. Just don't go too cheap on the CAT...some of the $40 Ebay CAT's won't last a year...ask me how I know. :thumbdown:

Recap: your engine is fine, you should replace your O2 sensor IMO. And tell your boys that you meant to do that...
 

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You should have had some of the local rednecks there to watch it - you would have impressed the heck out of them.
 

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Will not having a cat (or having a toasted one) send improper data to the ECM or PCM? I'm not sure how much my '89 spider relies on the cat.

Thanks for the suggestion. That bears looking into.

M-5
No, the catalytic converter has nothing to do with that stuff and to set the record straight I am not advocating wanton pollution of the environment. The millions of Hyundai Sonatas, Toyota Camrys and Chevrolet Silverados being driven on daily work commutes should indeed have Cats but the handful of mid 70's to mid 90's Alfa Spiders being driven occasionally can certainly do without them if nobody is forcing you to use one.
 

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Discussion Starter #12
You should have had some of the local rednecks there to watch it - you would have impressed the heck out of them.
:laugh: Too funny! I wasn't expecting to start with "Hay y'all watch this!!"

Anyway. Started her back up today. She seemed fine and could not find any leaks. My son and I took her around the neighborhood streets. Kept her at speeds of 25-40 mph. I wanted to see how she reacted when warmed up before trying to take her out on the county roads and getting her up to 55mph.

On two separate occasions (once she was warmed up) power went to hell. She sputtered and bucked like she was doing 10 mph in 5th gear only we were geared properly. Each time I pulled over and waited about ten minutes, then she started right back up.

When we got home I let her idle in the garage to see if she'd overheat. She idled steady at about 1000rpm for about 15 minutes. Then she dropped to about 800, then about 500 and stalled, not to start again.

The temp gauge went no higher than 180 (f) the whole time and it seemed she had good circulation throughout.

Are these symptoms characteristic of a bad O2 sensor? I definitely want to replace the rear and center mufflers as the direct bolt on replacements are both readily available and relatively affordable. The CAT on the other hand is rather expensive if I choose the bolt on version.

My thoughts are: (please tell me if I'm missing something)

1 Replace O2 sensor, center exhaust and rear exhaust,

If I still have drivability issues:

2 Replace CAT with a Magnaflow and have a shop attach it to factory pipes. This is much more affordable than the bolt on version.

Anything else I should consider??

Thanks-M5
 

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Are these symptoms characteristic of a bad O2 sensor?
No. But that doesn't mean the O2 sensor is OK.

If the O2 sensor is faulty the computer will ignore it and default to a pre-programmed fuel map which is slightly rich. Running very rich (or slightly rich for too long) hastens the catalytic converter's demise.

I thiink a partially plugged catalytic converter would explain your car's symptoms. If you have the original catalytic converter it is lilkely overdue for replacement. Most any 'modern' cat will flow better than the originals did even when they are not plugged up. I don't know the current costs but I had a local shop weld in a new cat a few years ago and it cost less then $150.

If you find that the cat has failed then you should also replace the O2 sensor. Otherwise the new cat will not last very long. There is info about generic replacements in the Spider FAQ thread. Usually you have to re-use the original wire harness parts so don't toss that away.
 

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This is from a data sheet for a Bosch sensor. Do you think that you may have exceeded these temperatures?
Exhaust gas temperature range(max.) for short time< 1,030°C
Hexagon temperature< 570°C
Cable and protective sleeve tem-perature< 250°C
Connector temperature< 120°CStorage temperature range-40 to 100°CMax.
 
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