Clogged Cats

[shodown220]

So my SHO doesn't feel as fast as it did when i first got it. I have also had people tell me that it smokes some when WOT. I have read a lot of posts about having clogged cats. What are the symptoms of clogged cats? And how can i check to see if they are clogged? What can i do if they are clogged? Any input is greatly appreciated!

 

[SASHO91]

if they are really clogged:
1: you will have bad gas mileage...
2: if you tap the bottom of the cat, more tha likely you should hear something vibrating in there.. thats the catalyst...
there is some more stuff as well... just cant think of them right now.. others should chime in...

 

[TicoSHO]

My cats were clogged and I couldn't keep the engine running when at temp. It would just shut itself off. That sounds like what I have now. Does it drive better before it get to running temp? I think mine is the DIS (I got a #2 coil code a little while back). Let us know what it finnaly is.

 

[shodown220]

Yea it drives good when first cranked. Sometimes wants to cut off after getting up to temp and maybe just a little hard driving. So what would i do if the cats are clogged?? Also, yes it does have pretty bad gas mileage...

 

[TicoSHO]

It cost me about $500-$600 for new y-pipe w/cats and new O2s. Not an problem since. There are other solutions that someone else may have.

 

[LeddZepp8687]

Just buy a catco Y-pipe, its a perfect replacement and its like 200 something bucks...Maybe even have a shop weld some hi-flow cats in there???

 

[SASHO91]

magnaflow has a pipe for 257 IIRC... its on summits website....

 

[wood_e]

He has an ATX... do a search for ATX y pipe and you should find a recent thread on where to find a replacement cheaply.

 

[shodown220]

ive heard if the cats are clogged, you could smell it, is this true? Also, could it just be 02 sensors that are causing this??

 

[ManySHOs]

Causes what? Smoke at WOT? Many SHO's smoke at WOT. Is it black smoke, blue smoke, white? If it's just a little bit of black soot, I wouldn't worry about it. As these cars get higher in mileage, blue smoke from burning oil is starting to become the norm. That doesn't mean that there isn't a problem as something is obviously leaking into the combustion chambers. However, it may not be a huge issue unless you are burning a ton of oil. If you floor it at night and check your review mirror, do you see the smoke in the headlights of the cars behind you?

Ian

 

[stevemainian]

Tap the cats, if you hear something that sounds like pennys and quarters flying around, problem found. Clogged cats will make the car run like ****. No gas mileage, no acceleration since theres an overage in backpressure. If theyre clogged, theyre clogged. Only thing is a replacement, and cats are expensive.. it doesnt help they contain platinum either.

 

[SuperHO]

Causes what? Smoke at WOT? Many SHO's smoke at WOT. Is it black smoke, blue smoke, white? If it's just a little bit of black soot, I wouldn't worry about it. As these cars get higher in mileage, blue smoke from burning oil is starting to become the norm. That doesn't mean that there isn't a problem as something is obviously leaking into the combustion chambers. However, it may not be a huge issue unless you are burning a ton of oil. If you floor it at night and check your review mirror, do you see the smoke in the headlights of the cars behind you?

Ian

I see smoke in people's headlights, but it ain't oil smoke....something about a Doug Lewis superchip riching things up a lil and having dropped my y-pipe repeatedly on the pavement and shaking a bunch of burnt platinum out...

 

[91_SHOster]

would glowing red hot cats also be a sign of clogged cats??

 

[SuperHO]

Ummmmm....yeah.

 

[SHOslyter485]

would glowing red hot cats also be a sign of clogged cats??

Glowing red cats could also mean that the car is getting too much fuel, and that excess fuel is burning off inside the cat, making them glow red. Not necessarily a bad cat, but it will toast a cat quickly

If you do find out they are clogged, you'll need to replace them . If you don't already have a y-pipe installed, get one.

 

[SonicRiot]

Either way, once the cats are glowing for any significant length of time, they're shot.

Any signs of misfires? It's a '94, you should be able to monitor the Pre-cat O2s to see if you have a rich condition. Or just hook up a scope to each one...

Blue smoke will NEVER be normal from a gasoline car... you're burning oil if you see blue. I don't care how old the car is, sum'um ain't ryight!!