BimRon

Ok, I've already been properly shamed by my friends. I won't do it again, like this. I promise. I'm also suffering the sting of loosing money.
I bought a CAT from Amazon, and it said that it would fit. Later, something made me want to look at it again and read through everything. I saw that the CAT I bought was only good for Firebird models up to 1995 (Walker Exhaust EPA 15042). What I needed was the Walker Exhaust Ultra EPA 93303. The wrong CAT has already been welded on. The repair shop is finishing up my muffler replacement this morning (2/23/22).

My question is: What problems can I expect from my exhaust, until I get the CAT replaced?

B52bombardier1

If the repair shop gets it to fit and welded on, I think your situtation will be OK and at this point, you obviously can't return it. Reset all DTC's and any Check Engine lights and see what happens.

Rick

BimRon

Thanks for sharing your thoughts Rick. The CAT fit on my firebird just fine. I drove my car for about 30 minutes. I'm not having my usual acceleration issue, as for now (I posted another thread "Help me: Code P0405"). Rush hour traffic started picking up so I couldn't get on the highway for a good long stretch. Later this evening I'll give it a good run on the highway.

99 Black Bird T/A

iTrader: (4)

Looks like there is about 4 pounds of weight difference in the two and the OBD1 is the lightweight. As exhaust systems go, OBD I vs OBD II's have more efficient cat(s).

Since the muffler shop made it fit I doubt the car will have any issues with the OBD1 cat.

There's a very very very small risk of failing the visual portion of the smog check if your car has to have that.

The smog tech would have to be a extremely OCD to notice the cat isn't OBD II compliant. There a law smog techs are supposed to follow, and the law states all OBD II vehicles must have an OEM cat, or an approved replacement OBD II compliant aftermarket cat. So smog techs are SUPPOSED to look at the CAT, and if it is not an OBD II CAT on an OBD II vehicle, fail it.

Do smog techs pay attention? I highly doubt it...do most smog techs even KNOW how to tell the difference? Highly unlikely.

Would they even care enough irrelevant nonsense to be a jerk and fail a car or truck that passed everything else for the smog check? I would hope not.

Kjduvall

As long as it runs/ drives fine and passes , I wouldn't worry about it. In my experience when cats really go to **** the remaining junk is stuck in or before the muffler and that usually led to most problems anyway, ( lack of performance and terrible gas mileage/ with a side of engine light on).

BimRon

Flowmaster created the American Thunder for the 4th Gen Firebirds and Camaros. The stock 2001 Firebird has a single exhaust; I wanted to upgrade to dual exhaust (I plan to get LED tips). I also wanted to give my Firebird just a little rumble to the sound. The shop did a good job on the install. I'm no welder, but it looks good to me. I was too excited and didn't get pics of the underbody welding.

I was not impressed with the sound. I don't know if having the wrong catalytic converter installed was to blame, or maybe the engine size. I know the American Thunder (AT) was made with the V8 5.7L engine in mind. My Firebird is a V6 automatic. (I bought the car for "the look", not be a Hot Rod. I've had the car since 2004.)

My car does sound deeper, but there is no "throaty" (or rumble) sound. When I first start up the car it sound good, deep, and has throat! Then it settles into a mono-tone drone sound when idling and driving. When I'm coming off the acceleration, it gives me that throaty sound. If it's not going to sound right, I'd rather go back to a stock muffler. Who knows, maybe I need to get used to it? That mono-tone drone sounds like a car with a bad muffler to me.

I didn't go with a Magnaflow muffler, because I heard their mufflers use sound packing media. As the Magnaflow gets older the packing will degrade, and the sound will change; so I heard.

I'll try to get some pics and sound bites posted.

What are your thoughts?

68Formula

If the converter isn't efficient enough, then the downstream O2 sensor won't get the proper response and set a check engine light. Not sure if 30 minutes driving is enough time to verify it's happy. It may take a few more miles. Or since it's new, it might be efficient enough for now; but as it ages will need to be replaced earlier than the correct converter would have required.

SteveC

As long as you are not in a smog certification state (thanks California), it should not be an issue.

BimRon

My firebird is running just fine. I don't have any warning lights in my vehicle.