95z28 -quicksilver

Ok, heres the deal, the car is starting to sound different, is down on power, and has a high RPM miss... I already have a thread about the miss but I have already replaced every ignition part and its still doing it.... But my question is, what are symptoms of a clogged cat? The cat is original, and there hasnt been any AIR or EGR hooked up on the car for a good 45 - 50 K.... Thanks.


Chris

madwolf

When my cat was clogged, it started with a change in sound, loss of power and the car would simply not rev past a certain point. It gradually went down to the point where I could barely rev the car to 2000 RPM. It wouldn't even go up a small hill.

Best way to find out is if you can open up one (or both) of the AIR plugs and see if it will perform any better. You can also make a nickel size hole right before the cat to test.

95z28 -quicksilver

So when you say it "simply wouldnt rev past a certain point", what did it do when you tried? Because mine will miss and kinda stumble at about 5K now.....

madwolf

Well that could also be your opti, but mine just gradually went down from 5000 to 1500.

95z28 -quicksilver

Its got a new opti.... I'm on my 3rd one actually, LOL. If its the opti again... I'm getting an LS1.

BigBlue95Z

Go to ghettoZone and get a vacuum gauge and hook it up to a vacuum source. Rev your motor to about 2.5k and hold it there for about 3sec and then let off. Your vac should be high at idle and then when you go to 2.5k, it will drop, when you let off, if it stays low(10-15psi) then your cat could be clogged.

Mtdewandal

When mine was clogged the car got really quiet at idle and when I revved it to about 4000 rpm it stumbled and wouldn't rev any higher, almost like it was suddenly tied to a stump. I pulled off the Y-pipe and found out the converter was breaking apart inside. Plus I could smell the exhaust backing up as well.

)2overt SS

1) You will definately hear a change in tone (will be muffled)

2) Loss in power.

944v8inDFW

My cat was clogged. It made a lot of noise, wondered around the house aimlessly and wouldnt eat. I finally gave it a tiny bit of exlax in its food. Now he is sh**tin like a christmas goose

... tap tap.....
...whisper whisper...

What the hell you mean this is a car forum, and not that kind of cat???

oops
my bad

95z28 -quicksilver

95z28 -quicksilver

Yeah, and it has been smelling differently too..... Maybe i should just buy a highflow....

ny_z28man

I think autozone has pressure guages and adaptors to rent from them if you need to. Unscrew your precat O2 sensor and screw in the adaptor and hook it up to the pressure gauge. I think anything over 2PSI isnt good. If your getting lots of presure then your cat (or farther down the exhaust system) is clogged up. Its not the easiest way to do it but its a sure fire way to find a cog in the exhaust system. If you have a lazer temp reader check the temp of the exhaust pipe after the cat and before the cat. You'll find a clog by the huge temp drop. Check the whole system sometimes the inside of the cat can break apart and plug up farther down the pipe or in the muffler. Hope this helps ya.
-Paul

944v8inDFW

Yeah when my cat was clogged it smelled "different" to. I would find little piles......

DAMN!!! Wrong forum again

kevm14

Hey cool. That happened to my 93 Caprice 9C1. It got quiet and was making a strange whistling sound. And I saw white "smoke" coming from the exhaust. Turns out it was the cat disintegrating. I got about 10 miles on the car after I started seeing the dust and I went accelerate hard off the line and as soon as the tach hit like 4000rpm, the car just died. I was able to restart but it wouldn't do much more than 15mph. That was a pretty cool time. I thought I blew my engine.

95z28 -quicksilver

Ok so i am getting a test pipe put in on wednesday, so we will see if a clogged CAT CONVERTER is the problem. Hopefully so, maybe the clogged cat caused my 02's to foul out and that is the culprit of my high rpm miss.... That would be cool, lol. Anyways, thanks guys.


Chris