Catalytic convertor

Catalytic convertor

Postby Lukybernas [OP] » July 4th 2016, 1:04pm

Hi guys, got 2003 Astro with 250k and the P0420 turned on few weeks ago together with lower power and the muffler heated so much that you could feel it stepping on the floor a lot. Didnt have 1500 to change the cat but took it to garage few days back and they said it's California version with two cats in a row and if one's plugged it's the first (smaller) one and so they cut it out replacing with pipe. It didn't seem plugged, power's bit back but muffler still heatin. Not sure what's wrong and what to do, shouldn't they have cut out the whole cat? Thanks for advice!
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Re: Catalytic convertor

Postby WimpTech » July 4th 2016, 2:45pm

I'm no expert, but i stayed at a Holiday Inn once.
Sounds like a plugged cat still. Pull the upstream o2 sensor out and see if it runs better (will be loud, fyi). If so, plugged cat and/ or muffler. If you have a gauge, you can measure back pressure, should be around 1.4 psi. Search amazon for B00KRJFSFQ for a gauge.

Next, start looking at what wiped out the cat, like bad plugs, wires, distributor, etc.

Good luck
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Re: Catalytic convertor

Postby markmitch » July 4th 2016, 3:56pm

a bad head gasket can clog your exhaust to been there done that. Just saying
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Re: Catalytic convertor

Postby AstroWill » July 4th 2016, 7:03pm

Lukybernas wrote: Didnt have 1500 to change the cat


Get the weld in cat and have a muffler shop weld it in for cheap, after fixing what caused it to fail in the first place.

Tuneup including checking the distributor drive gear, probably the number 1 killer of cats. Check the links in my sig.

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Re: Catalytic convertor

Postby Surfin Safari » July 5th 2016, 12:08am

Get or borrow an OBDII scan tool and start checking things out. An overheated cat is usually caused by an extremely rich fuel mixture. The catalyst starts working overtime to try to burn off the un burned hydrocarbons.It starts to turn cherry red hot
JTwm8Sj.jpg
Overheated Cat
I have seen them go full red from one end to the other. The honeycomb catalyst starts to melt and will plug up. The engine needs air to run but after the combustion takes place it has to get rid of the exhaust gases if they have nowhere to go then there is no room for the fresh air to go and the engine loses power. So Find out why it is running rich. Then fix the problem and replace the cat.
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Re: Catalytic convertor

Postby Astrofarian » July 5th 2016, 2:14pm

THAT, right there, looks like more of a CATACLYSMIC convertor. Don't be parking that one in any tall, dry grass.
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Re: Catalytic convertor

Postby Lukybernas [OP] » July 5th 2016, 8:06pm

AstroWill wrote:
Lukybernas wrote: Didnt have 1500 to change the cat


Get the weld in cat and have a muffler shop weld it in for cheap, after fixing what caused it to fail in the first place.

Tuneup including checking the distributor drive gear, probably the number 1 killer of cats. Check the links in my sig.


I made the tuneup few months ago so maybe it's the aftermath of it... Thanks :)
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Re: Catalytic convertor

Postby WimpTech » July 5th 2016, 9:32pm

OK cool. Did you pull the O2 sensors and see if it ran better/ more power? You should be able to feel the exhaust out the tailpipe. If you are not sure how much is good or bad, compare with a newer low mile car, or that has a new cat haha.
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Re: Catalytic convertor

Postby Lukybernas [OP] » July 5th 2016, 10:10pm

Wimpazz wrote:OK cool. Did you pull the O2 sensors and see if it ran better/ more power? You should be able to feel the exhaust out the tailpipe. If you are not sure how much is good or bad, compare with a newer low mile car, or that has a new cat haha.


Well that's something I'm not really able to do on my own as I'm on the road without having much tools so I basically rely on garages but the guy didn't even check the computer and cut the first cat (of two) off with saying "doesn't seem plugged to me" and replaced it with a pipe and charged me 90 bucks for it, done heh...
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Re: Catalytic convertor

Postby WimpTech » July 5th 2016, 10:49pm

Lukybernas wrote:
Well that's something I'm not really able to do on my own as I'm on the road without having much tools so I basically rely on garages but the guy didn't even check the computer and cut the first cat (of two) off with saying "doesn't seem plugged to me" and replaced it with a pipe and charged me 90 bucks for it, done heh...


I believe it is an 18mm wrench to remove the O2 sensor, could be wrong... that's it. If you can't have regular access to tools, this might not be the vehicle for you. Shop bills will add up quick, so my advise is get yourself a decent tool set together to carry and learn some basics. I once fixed a rental car in the LAPS parking lot while stranded in a small town... got it running and even made the meeting on time... and I'm an idiot.
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Re: Catalytic convertor

Postby astrotardis » October 14th 2016, 12:04am

A friend's car caught on fire like that he had a rust hole he didn't know about in the floorboard of his crown Victoria and his cat was clogged bad . Well any way the insulation and carpet over the years got pushed through rust hole and was sitting right on his cat and viola car fire!!! he gets mad when we call him hot feet now..
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Re: Catalytic convertor

Postby JuneauCabbie » October 16th 2016, 7:15am

My '03 Safari had that problem, and it turned out that replacing the cat converter and all the oxy sensors did NOT fix the problem, since the exhaust system had been replaced before I bought it.

There was no pre-cat converter (which your mechanic removed) which was why the cat converter for that year was not working right. Someone on this group asked me about the pre-cat and when I check parts catalog sure enough exhaust system showed one.

I ordered a full exhaust system online that included pre-cat, cat, and muffler and had my wrench install it for me, and had no exhaust problems for the next 120k miles until I sold it with 278k miles on it.

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