Clogged exhaust question

Ok I know for sure that my sons car has a clog in the exhaust. I pulled the primary o2 sensor and got 25 psi of pressure at 2k rpm. I got the same results at the secondary o2 sensor as well. The car went to zero vacuum at 2k rpm in drive with the vacuum test. When I split the exhaust at the flange for the y pipe the back pressure was gone and the vacuum test shows about 7 inches at 2500 rpm. The motor also pulls pretty hard during the open test where it hit a wall with the exhaust closed. Now I’m left with the single secondary cat and the muffler as the possible clog.

My question now is how can the secondary cat be that clogged while both primary cats ( bank 1 and 2) are fine? What could possibly cause such a backup in the system? Personally I was leaning towards the muffler only because I’ve never seen so much water pour out the exhaust as on this car and I was thinking that maybe the muffler ( original ) was rusted up inside.

Thoughts?

You can maybe get way with gutting that piece before muffler

Or again cut between and add this back onto system.

Cats are a mesh screen.

Anything can happen wouldn’t put much into it.

Goal here was to see if car ran without falling on its face.

To say exhaust over engine issue

Here you found engine runs fine

Well the next and final stage is the harder one. I’m going to have to cut into the system somewhere after the second cat and see if there is any back pressure still. If there is then I’m going to gut that sucker and put it back on. If it’s the muffler that at least isn’t too hard as it’s in the back near the bumper

toomanytoys said:

Well the next and final stage is the harder one. I’m going to have to cut into the system somewhere after the second cat and see if there is any back pressure still. If there is then I’m going to gut that sucker and put it back on. If it’s the muffler that at least isn’t too hard as it’s in the back near the bumper

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Saws all works well

How rusted is system

Salt water and salt for snow your lucky it last a few years

Rust is minimal. I think it’s a low quality stainless. Pipes are brown. Muffler looks meh

toomanytoys said:

Rust is minimal. I think it’s a low quality stainless. Pipes are brown. Muffler looks meh

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Its T409.

Just give the secondary cat the heave ho and throw in a piece of tubing from pepboys. If its still clogged, throw a cheap-o jegs or summit turbo muffler on it and be done with it.

kevinatfms said:

Its T409.

Just give the secondary cat the heave ho and throw in a piece of tubing from pepboys. If its still clogged, throw a cheap-o jegs or summit turbo muffler on it and be done with it.

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Here is where if he guts it.

It’s still there is someone was to look.

Who can say it didn’t empty itself

Some of these states still have hell to pass inspection

I live in NYC and inspection here is plug into the aldl and a quick visual. Shouldn’t be a problem if I replaced that pipe