What causes catalytic converter damage?

[npritchard777]

I installed my Corsa system over the weekend and discovered that both my cats are bad. The passenger side cat actually had broken down and a big chunk fell out when the exhaust was cut off it. The driver side is nearly black but hadn't blown apart like the passenger. So I'm wondering what would be the most likely cause this much wear? The car has about 72k miles on it.

I've got a set of FIC injectors sitting in the garage waiting for me to get enough motivation to pull the plenum again. Could the stock injectors cause damage to the cats with bad flow rates?

-Nate

[gbrtng]

Running too rich OR too lean hurts them. And excessive oil usage kills their efficiency over time.

[GOLDCYLON]

As stated above but also impact due to speed bumps, potholes etc damage the honeycomb substrate until it starts breaking apart. Also 72K is about right. THe black may have been previous damage before the injectors were replaced.

If you need a factory replacement passenger side I have one low mileage one about 18K miles on it I picked up in the actic (complete) As you well know the cats and exhaust header are intergrated on the 90-91s.

[npritchard777]

I actually haven't replaced the injectors yet. I've been dreading pulling the plenum (again) but I'll probably get to that this winter. I'll get back to you on the cat. The guy that did my Corsa was supposed to get back to me yesterday to let me know if/when replacement cats would be in.

With these integrated exhaust/cat, can the cat still be replaced without messing with the exhaust manifold?

-Nate

[GOLDCYLON]

No the 90-91 cats are one unit. So to deal with the cats your going to have to pull the exhaust manifolds on both sides. These are NLA from GM. GM made them seperate units in 92 and the rest of the model run. If he can find a factory replacement I would be very surprised

[npritchard777]

Well that sucks. Maybe I should just hold off for a while and save some pennies for headers.

-Nate

[npritchard777]

Oh, it wasn't factory replacement he was talking about. I think he said he found them from Magnaflow.

-Nate

[GOLDCYLON]

Yep I kinda figurered that as im running MFs on my car now but good luck getting it to pass emissions. Mine doesnt and CA is even more anal than AZ. Im running Jeal Long Tubes, With MF High FLow Cats and a Corsa system. With the original Cats I passed no problem.

[Dynomite]

Yep I kinda figurered that as im running MFs on my car now but good luck getting it to pass emissions. Mine doesnt and CA is even more anal than AZ. Im running Jeal Long Tubes, With MF High FLow Cats and a Corsa system. With the original Cats I passed no problem.

I Prolly will install SW headers and exhaust :D AND will be registering ZR1 in South Dakota :dancing:dancing:dancing There are NO vehicle emissions checks in good ole SD for licensing. I think I will run SW offroad headers without CATS :D

[GOLDCYLON]

I Prolly will install SW headers and exhaust :D AND will be registering ZR1 in South Dakota :dancing:dancing:dancing There are NO vehicle emissions checks in good ole SD for licensing.


Which is why my Z is registered in Flagstaff ;)

[GOLDCYLON]

Well that sucks. Maybe I should just hold off for a while and save some pennies for headers.

-Nate

I dont thnk any headers for CA are CARB approved. Sorry bro

[npritchard777]

I was looking through some old posts and saw TomC (tccrab) had done his homework. I sent him a private message and this is what he sent back. Sounds like I might as well give it a shot;

-------------------------------------------------


Nate:

Howdy!
It's a legal loophole that allows us to have non-CARB approved aftermarket exhaust headers on '90-92 ZR1's only.
Here's how it goes:
First, take the car down to a SMOG shop and have them fail it for the bad Cat. Make sure they document that the Cat is bad and needs replaced.
Get the smog shop to set help you set an appointment for a referee inspection.
Then go down to your local Chevy shop and have them search for a replacement exhaust header/cat.
They will tell you that there are none, haven't been any for years.
Have the parts manager write you a note stating this.
Order up a set of headers, but be sure to have the air injection hoses and pipes installed on them. Buy a pair of Cats that are CARB approved (there are quite a selection)
Take the headers and the cats down to the referee, explain to them that the old cat has failed and there are NO OEM replacements available anywhere.
Remind the referee that you know that you can't legally buy a used cat here in CA so that means you have to go with aftermarket equipment.
No headers for a ZR1 were ever CARB approved, so they will have to accept whatever headers you show them as long as they have all the correct SMOG hoses.
The referee will write you an exemption.

You can of course buy a set of good used stock manifolds and cats from a fellow forum member and install them yourself. It's not exactly legal, but nobody but you would ever know that you illegally bought a used catalytic converter and installed it on your car.
This is actually the cheapest way to go, there's a lot of guys who have headers on their cars in places where the SMOG nazi's haven't taken over.
I've seen them sell for as little as a couple of hundred dollars for the pair.

Good luck!!

TomC
"Crabs" __________________
TomC
'90ZR1 #792
Honorary Pirate
http://i71.photobucket.com/albums/i159/tccrab/arg.gif

I can break every speed law in the country going into 2nd gear.
There's 4 gears after that.