Pre-Cat Question
Thread Starter
Melting Slicks
Joined: Mar 2003
Posts: 2,898
Likes: 0
From: Oklahoma City Oklahoma
Pre-Cat Question
Are the pre-cats on these cars as restrictive as the main cat, or are they more restrictive than the main cat? It was my assumption that they are nearly as restrictive, but I was told that they have virtually no restriction at all. I am reinstalling mine tomorrow, in hopes that it will help my little Code 32 problem. I had no codes till I pulled them off. I'm working backwards with this, but I want to find out if the pre-cats had anything to do with the code being set, or if it was just coincidence. I know I probably have an EGR problem somewhere, but if the pre-cats create enough back pressure to make the system work, it might buy me a little time. TIA
BTW...the main cat has been gone for quite some time, so I'm considering that aspect a non-issue.
BTW...the main cat has been gone for quite some time, so I'm considering that aspect a non-issue.
Team Owner
Joined: Sep 2001
Posts: 62,157
Likes: 1,732
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
They do little of the work, you would be better off adding a new main cat back in.
But they are the same 70's era cats, just smaller, so they are as restrictive.
But they are the same 70's era cats, just smaller, so they are as restrictive.
Team Owner
Joined: May 2006
Posts: 21,473
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From: Palmdale, Ca----- 2009 Cyber Gray 4LT A6 F55 452 RWHP 422 RWTQ- RIP 1998 C5 734 RWHP & 585 RWTQ-----
Any Cat is restrictive unless you have purchased a Super High Flow after market Cat from the industry. If you want to keep your two pre-cat's you could if anything purchase a couple of High flow's to put there instead.
As far as the problem with the code I would agree that it is a coincidence, might be a little something more(not much though)!
Thanks,Matt
As far as the problem with the code I would agree that it is a coincidence, might be a little something more(not much though)!
Thanks,Matt
Thread Starter
Melting Slicks
Joined: Mar 2003
Posts: 2,898
Likes: 0
From: Oklahoma City Oklahoma
Had the OEM y-pipe w/pre-cats reinstalled this morning, took that
%&$# Stage II chip w/EGR delete out.....took it out and drove it all over town on the freeway, using the cruise, and foot.....NO LIGHT/NO CODES!
The car is running cooler, oil temp seems to be down a bit, and no pinging. I probably have a potential EGR problem, I admit, because the removal of the pre-cats/main cat shouldn't have triggered an EGR fault code on a car this old, but this should buy me a little time before I have to get serious about tracking the problem down.
%&$# Stage II chip w/EGR delete out.....took it out and drove it all over town on the freeway, using the cruise, and foot.....NO LIGHT/NO CODES!
The car is running cooler, oil temp seems to be down a bit, and no pinging. I probably have a potential EGR problem, I admit, because the removal of the pre-cats/main cat shouldn't have triggered an EGR fault code on a car this old, but this should buy me a little time before I have to get serious about tracking the problem down.
Drifting
Joined: Mar 2004
Posts: 1,504
Likes: 0
From: Byron Center MI
I removed the pre-cats and main cat on my '89 last year and started triggering a code right away. I added some Seafoam to the tank a couple of times and now no code. I think the Seafoam cleaned the EGR valve. By the way I only put the Seafoam in the tank.
