CAT Clogging

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bdj5773

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OK. Thinking about buying a 2003 LS with only 74,000. Sharp looking car. The fellow who is selling said the CATS keep clogging up and that he just hollowed them out. As such, the engine light is on and therefore will not pass inspection. The way he said it peaked my interest -- "keep clogging up." I'm not sure exactly what he meant by this, but what would cause a CAT to keep on clogging up? Any help or advisement on this issue would be much appreciated. I don't want to buy trouble. But, if I can get a good deal and only have to do a little work, that would be great!:D
 
bdj5773 said:
OK. Thinking about buying a 2003 LS with only 74,000. Sharp looking car. The fellow who is selling said the CATS keep clogging up and that he just hollowed them out. As such, the engine light is on and therefore will not pass inspection. The way he said it peaked my interest -- "keep clogging up." I'm not sure exactly what he meant by this, but what would cause a CAT to keep on clogging up? Any help or advisement on this issue would be much appreciated. I don't want to buy trouble. But, if I can get a good deal and only have to do a little work, that would be great!:D
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That's easy. It's the number one LS engine problem. Marginal COPs (Coil-On-Plug) ignition. The solution is to replace all eight or six (V8 or V6) COPs and all eight or six spark-plugs. Expect to have to do this every 60 to 90K miles.

(The 03 V8 has a 10 year /100K mile extended warranty for the COPs, but the 10 year part may have already expired.)

Also, if there is oil in the spark plug wells, you will have to replace the valve cover gaskets.

The marginal COPs cause misfires. Misfires send raw gasoline into the cats, where it burns and melts the guts of the cats together.
 
so it sounds to me like his mis fires destroyed his cats, then he got them replaced and didn't fix the misfire, which then burned up his next set of cats.

I'm kinda wondering how many sets has he went through. lol
 
I'm going to find out more about this. I appreciate the responses. I will definitely see if there is oil on the plugs. I have replaced one set of gaskets on an 01 LS and I don't want to do that job again. :mad:
 
joegr said:
That's easy. It's the number one LS engine problem. Marginal COPs (Coil-On-Plug) ignition. The solution is to replace all eight or six (V8 or V6) COPs and all eight or six spark-plugs. Expect to have to do this every 60 to 90K miles.

(The 03 V8 has a 10 year /100K mile extended warranty for the COPs, but the 10 year part may have already expired.)

Also, if there is oil in the spark plug wells, you will have to replace the valve cover gaskets.

The marginal COPs cause misfires. Misfires send raw gasoline into the cats, where it burns and melts the guts of the cats together.
Click to expand...

You mentioned "marginal COPs." What do you mean by "marginal?" I just replaced my coils on my 2001 LS that has 215,000 miles. I bought the car with around 80,000 miles and never had to replace the ignition coils until now. The CATS have never been replaced. I did replace the gaskets a couple of summers ago, though, and no oil leaks since. I just don't want to do it again, but it could very well be the case that this 03 LS I'm thinking about buying has that problem. I could take a few plugs out and see what I discover. But, they are a pain to get to.
 
From what I've learned from this forum marginal cops are failing, on their way out, missing but not to the point to trip the computer to say there is something wrong. Again, from this forum, when under warranty, the dealer will run stress tests to determine the marginal or failing cop causing misfires. I'm not sure of the count, but I don't think one misfire will trip a check engine light, it's a series of misfires in a given amount time. Long story short, a marginal cop is simply that, a cop that is almost insufficient to function.

From the sounds of it you could walk away with a steal of a deal but CATs aren't cheap, at least the factory ones are not. Considering the care this owner showed for the car it doesn't sound like something I would walk into. What's to say he put a band aid over something else and it goes unnoticed.
 
All I can do is look it over and especially see if there is any oil on the plugs. It's funny, my 01 LS never did have the issues with the coils going bad until 215,000 miles and only one was bad but I replaced them all because I got 8 free coils from a friend he didn't need. Another did go by around 180,000 miles. So, I have 8 brand new ones I could use. CATS should be well under $100 a piece to replace, correct? It does only have 74,000 miles on it, so that is appealing. He is asking $7,000 and haven't even negotiated any yet. Is there any way to keep these coils from going by so quickly; any particular brand? I just don't want to get trouble!! Can't afford it.
 
as defined by merriam webster, marginal: close to the lower limit of qualification, acceptability, or function : barely exceeding the minimum requirements

a failed coil doesn't work at all, a marginal coil works fine most of the time, but its that "rest of the time" that is important.
 
Visteon 1008 ... dg 592 I believe? ( do a search or correct me if I'm wrong) Were on ebay for 200 a set of 8 a wile back, now 30 a piece (coils) . Visteon is oem replacement and owned by ford ? So you're lookin 240 approx, plus gasket and plugs? ....ngk irridium is what came stock I believe also. Cats and probably 02 sensors wouldn't be bad. that's my best guess for that problem.
 
A replacement CAT from the dealer will run you $1500 or so. I think there are universal ones you'll be able to use however that will obviously cost much less. Perhaps, find a wrecked one and cut 'em off of that. Assuming that those were not run on misfires of course. Not sure about that but some members have run different CATs on their cars. I'm not digging for threads to find 'em.
 
I have Thunderbolt universal CATs and so far they work great. You have to weld in your own O2 sensor bungs and have the CATs welded in but they only cost $80-90 for the pair. They are high flow universal 2.25" in and 2.25" out.
 
hite337 said:
I have Thunderbolt universal CATs and so far they work great. You have to weld in your own O2 sensor bungs and have the CATs welded in but they only cost $80-90 for the pair. They are high flow universal 2.25" in and 2.25" out.
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That right there is important info for what will surely be a future issue. I'll have to remember you have those to check the longevity when my time comes.
 
UPDATE: I didn't buy the 03 model. I found a super nice black 05 model. It has 84,000 models and is in great shape -- inside and out. I hope it's a good one.
 
Coming soon. I get the car later on this week...I will post pictures for sure.
 
this happened to me, i thought i blew my transmission took it to the shop, replaced all coils and cat converter, running like new, cost about 2gs with parts and labor and my car has a lil over 130k on it, also an 03
 
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