Catalytic Converter Problems

Reply Subscribe

Thread Tools

Search this Thread

Jan 5, 2011 | 09:08 AM

vabatwho714

Thread Starter

Intermediate

Joined: Mar 2009

Posts: 29

Likes: 0

Catalytic Converter Problems

I had posted earlier a problem that I was having with my 1991 that I had inherited from my Father. I had take a long road trip and on my return home when I would give it gas it would loose power. It would barely idle and if I tried to left off the clutch it would die. For the advice I received on here I have check the injectors, I bought a fuel pressure guage and hooked it to the fuel rail. I had 38 - 40 psi even after the car started loading up. Now that leaves me with the last thing on the list to check and that's the cat. Seeing there are three, how to I determine which one is bad. The car only has 35K and I'm leaning on it being the main cat due to the way it's acting. Any advice would really be great.

Jan 5, 2011 | 09:32 AM

Desert LT1 Vette

Racer

Joined: Nov 2010

Posts: 470

Likes: 5

From: elk grove,ca

few weeks ago there were few guys in here with cat problems.they bought new ones and passed smog.

Jan 5, 2011 | 12:32 PM

lt4obsesses

Le Mans Master

Joined: Dec 2006

Posts: 5,139

Likes: 482

From: H-Town Texas

Quote:

Originally Posted by vabatwho714

Actually, I would look at the precats first. They are the first in line and most suseptible to being roasted. Cats either melt and clog the system or break apart. It sounds like, if this is a cat problem that yours are melting. However, if your cats were damaged to the point that it causes the car lose power and not idle, I would think codes would be present. The SES would definitely be on. Don't forget about checking spark and vaccum.

Jan 5, 2011 | 12:39 PM

btr85vette

Instructor

Joined: Oct 2009

Posts: 202

Likes: 9

From: Tucson

I recently had a prob with the cat on my 85. No codes, it would idle ok, but bogged and pinged with any throttle. Yanked the cat, and it was nastly. Hogged it out, reinstalled it, and it ran better than it ever has. This is definitely worth a look.

Jan 5, 2011 | 01:04 PM

Siveck

Drifting

Joined: Aug 2002

Posts: 1,775

Likes: 125

From: Birmingham AL

Depending on your location, you might be able to install a new y-pipe with no precats and a new high flow main cat. This comes as a kit and is 49 state legal.

Jan 7, 2011 | 10:09 AM

vabatwho714

Thread Starter

Intermediate

Joined: Mar 2009

Posts: 29

Likes: 0

So, I know that there are very few lift points to get the car off the floor. Is the main cat welded to the Y tube coming from the engine? With the use of a couple of floor jacks, can I get the front end of the car high enough in the air to get the Y tube off the header and replaced with one without the pre-cats?

Jan 7, 2011 | 12:56 PM

btr85vette

Instructor

Joined: Oct 2009

Posts: 202

Likes: 9

From: Tucson

Just put your jack in the middle of the car and lift the whole side up. I do this all the time. You can definitely get the car high enough to work on anything, and its pretty fast.

Jan 7, 2011 | 05:03 PM

aklim

Team Owner

Joined: Jul 2004

Posts: 28,472

Likes: 3,290

From: Hartford WI

A stupid crazy idea but here it is. Can you disconnect the exhaust going into the cats and run it that way? Would that take out the O2 sensor? Not sure about a stock setup.