Catalytic converter question?

**DarkLord** · 04-18-2013

Hey gang. Now that we're past the coolant temperature sensor problem on
my son's 2001 Pontiac Grand Prix GT (3800 motor), it's time for the next
problem.

He is still complaining that it doesn't *quite* have the power that it had
when he first got it. He slapped it on the computer and right now its only
showing some kind of environmental equip. error (kinda vague to me). One
of his friends has a garage and gave it a quick once-over. He told my son
that his best guess was that the catalytic converter was going or gone.

We looked up the price at Advance and those danged things are $170-240.00,
pretty expensive stuff for an older car.

Is there any cheaper ones or can anything <cough> else be done, like replacing
it with a straight pipe, reaming the current converter out, or some solid after
market solution?

We live in Kentucky so we don't have to worry about California stuff.

Thanks for any and all help.

**Madness** · 04-18-2013

Don't go with a cheap or universal cat. It will throw a P0420 "almost" instantly.

**99PontiacGTP** · 04-18-2013

You can strait pipe it. you'll probably get a catalyst innefficency code from the rear 02 sensor but it shouldn't cause any driveability issues. thats the cheapest route.

**Fivefingerdeathpunch** · 04-18-2013

Originally Posted by 99PontiacGTP

You can strait pipe it. you'll probably get a catalyst innefficency code from the rear 02 sensor but it shouldn't cause any driveability issues. thats the cheapest route.

If only you knew.

01+ has cat diag in the PCM, it needs a cat there to not get crappy gas mileage.

And nobody better say "get a tune to fix that" because not everybody knows what those words mean or know anybody that can even do it.

**FordMan77** · 04-19-2013

Originally Posted by Fivefingerdeathpunch

If only you knew.

01+ has cat diag in the PCM, it needs a cat there to not get crappy gas mileage.

And nobody better say "get a tune to fix that" because not everybody knows what those words mean or know anybody that can even do it.

Ok, how's about he "aquires a program modified ECU to resolve the issue"?

**Fivefingerdeathpunch** · 04-19-2013

Don't be a smart ass now.

**GrandprixGT01** · 04-19-2013

Good time to get the 2.5 inch downpipe with high flow cat from zzp.

**smoke14** · 04-19-2013

I got the ZZP 2.5" cat'd dp, still throws the code. Light has been on for about 8 months now.

**GrandprixGT01** · 04-20-2013

Originally Posted by smoke14

I got the ZZP 2.5" cat'd dp, still throws the code. Light has been on for about 8 months now.

How much did the shipping come to for the 2.5" dp? I have been thinking about getting it for a while now.

**smoke14** · 04-20-2013

Was $220 I think to my door. $160 for the part, $40 for shipping and $20 brokerage fee at the border. Then installed it myself. The cat isn't Magnaflow as advertised, it's CanAmMex.

**smoke14** · 04-20-2013

**GrandprixGT01** · 04-21-2013

Did you notice better response getting rid of the ubend?

**smoke14** · 04-22-2013

Ya, I noticed a little bit more power above about 4k rpm and it also changed my exhaust note. However since we have e-test here I'd recommend buying it without the cheap cat. Buy a good cat. and get that welded in.

**Shiftingshaddow** · 04-22-2013

ZZPerformance - ZZP Downpipes #ZZ-GPDP

get the 2.5" with cat converter. its like 170 and 15 shipping. no probs with mine. or you can get the magnaflow from your parts store (might have to ship) and thats like 225. or maybe rockauto.com

there's probably a way to clean the stock one out though. google "how to clean catalytic converter"

dont straight pipe it. i did on a 99gtp and lost fuel economy and the engine light was always on.

before anyone jumps in to say i'm wrong.....no i'm not. that was the problem. stock cat back on=happy car

it was that simple.

**smoke14** · 04-22-2013

That's kinda what I was saying. Buy the ZZP dp. then buy a quality cat. 2.5"inlet/outlet and weld that into the dp. Then just bolt up the dp. These cars don't like cheap cats.

**BillBoost37** · 04-23-2013

Straight pipe plus the defouler trick and poof.. cheap easy and done.

However..I'd like to hear what that code was.

**Bandit1228** · 04-23-2013

Just as an FYI...If you're doing to work yourself and you do replace the CAT, you should look around to see about scrapping your old CAT. I've seen CATs sell for over $100 on ebay. At least you can make some money back so the investment in the new parts won't hit the wallet too hard.
I wish I would have known this before I brought my old CAT to a scrap yard and got a whopping $7.50 for it.

**smoke14** · 04-23-2013

Originally Posted by BillBoost37

Straight pipe plus the defouler trick and poof.. cheap easy and done.

However..I'd like to hear what that code was.

I have the P0420 code (same as a few others) and we need a cat. here to pass etest. I like the idea of the defouler thing.

**Shiftingshaddow** · 04-23-2013

Originally Posted by smoke14

I have the P0420 code (same as a few others) and we need a cat. here to pass etest. I like the idea of the defouler thing.

it was 3 years ago but i believe it was the p0420 code.
two mechanics told me that was the problem. one told me before i did it and said it would run like s#$+. he was right.

**jjmitch87** · 05-22-2013

Just got my sticker today (big fat R cuz P0420, no cat) thinking bout buying the high flow cat from wbody store (I think it was like 40-50$) and getting it welded in. Tossed around the idea about buying a new pipe with cat in but its way more than I'd like to spend. I'm looking for a 100$ fix haha