Possible clogged main cat...
Thread Starter
Racer
Joined: May 2002
Posts: 354
Likes: 0
From: Beach Cities SoCal
Possible clogged main cat...
My '90 has started stumbling on WOT. I started 'er up this morn and put my hand against both tail pipes and could stop the exhaust from emitting. Is that normal or should the exhaust being pumped at idle be to forceful to block the tail pipe on initial start up?
Drifting
Joined: Nov 2001
Posts: 1,498
Likes: 0
From: Bucks county Pa
Re: Possible clogged main cat... (Ivory90)
Its easy enough to drop the exhaust behind the cat and look at it. Or better yet hollow that main cat. The bigger problem is that the precats are more likely whats clogged and you cant easilt see inside. An in vestment in a front Ypipe, a hi flow cat and a cat back if you dont have one. Even if that aint your problem youll love it. :cheers:
Burning Brakes
Joined: Jan 2001
Posts: 1,169
Likes: 0
From: Manhattan
Re: Possible clogged main cat... (Ivory90)
sounds like an ignition problem.
you can get a back pressure test on the cats at a muffler shop. they'll measure the pressure before and after the cats to tell you if they're clogged. generally if your cats are clogged, the engine won't be able to rev above live 3000rpm.
i would check your spark plugs and wires, base timing, cap and rotor.
you can get a back pressure test on the cats at a muffler shop. they'll measure the pressure before and after the cats to tell you if they're clogged. generally if your cats are clogged, the engine won't be able to rev above live 3000rpm.
i would check your spark plugs and wires, base timing, cap and rotor.
Melting Slicks
Joined: Mar 2002
Posts: 3,252
Likes: 6
From: The Colony Tx
Re: Possible clogged main cat... (Ivory90)
I had my main cat clog about 18 months ago. They first replaced the pre-cats and then discovered it was the main cat. If you take it to a muffler shop have them try the following before they start replacing parts. Drill (or torch) a small hole behind the main cat and feel for air coming out of the hole. If you get a very small amount of exhaust gas then do the same just infront of the cat. If the cat is clogged you will get a strong exhaust thru the hole. This way you may save having to replace a pre-cat you don't need. :seeya
Instructor
Joined: Dec 1999
Posts: 127
Likes: 4
From: NJ
Re: Possible clogged main cat... (Ivory90)
I actually had a precat break into peices. A chunk of it was stuck where
the two precat pipes collect into 1. The pipe also turned cherry red not sure if that will happen in all cases.
Melting Slicks
Joined: Apr 2002
Posts: 3,305
Likes: 2
From: Havelock NC
Re: Possible clogged main cat... (aawil)
Sounds just like my problem and it ended up being the cats. I had small pieces of metal and ceramic coming out of my tail pipes, and there was hardly any exhaust pressure. My muffler guy put a high flow 3 way, and removed the old precats and welded in new pipes where the precats were for $240 bucks. I would recommend that over buying something and putting it on yourself. In my case it was cheaper to spend 240 to pay somebody to do the work than to spend 150 bucks for a front y from MAD plus a new 3 way which would prob run around $100. It still passes emissions because of the more efficient 3 way, has gobbs more power in every aspect, and sounds like a fighter plane under WOT(I also have muffler deletes). That's deffinately the way to go in my opinion.
[Modified by tarheelracer, 3:49 PM 9/27/2002]
[Modified by tarheelracer, 3:49 PM 9/27/2002]
