aftermarket catalytic converters

Back in October my catalytic converter died so I had an aftermarket one installed. Last week my cel came on and the shop said the cat was bad. So I had a different that I had put on. I'm a little concerned that the one cat only lasted 4 months but I'm trying to work with them on the warranty.

Also, are aftermarket cats supposed to be loud? When I press the gas it almost sounds like an exhaust leak. I originally thought the cat I had put on in October was leaking but the new one makes the same noise and the shop has assured me that there isn't a leak anywhere in the exhaust system. It just seems weird to me that they sound this way.

Does anyone have experience with aftermarket cats they can share?

I put a magnaflow aftermarket on a friends M3, passed NJ inspection with flying colors and then the insides fell apart 90 days later. They honored the warranty and sent a new one - its been in a long while now and still working.

I guess the quality of a $100 unit that replaces a $700 one should be assumed spotty and maybe just get 2 up front.

Yeah, I have Magnaflow universals on my 740iL. $65 each new vs over a grand for OEM. Not much of a decision even if they don't last as long. So far they've been on there since last September and no problems, though due to the higher flow, I had to mount the rear O2 sensors in spacers.

The federal government mandates all original pollution control equipment must last for 80,000 miles ( though it might be 100K now). Aftermarket suppliers have no such rules so their replacements can be much cheaper.

Even an aftermarket cat should last far longer than a few months. If the engine produces too much HC or NOX, the cat runs excessively hot. Take a look at your EGR system and make sure all the sensors are working properly. If your car is fuel injected, the spray patterns might be bad resulting in too much liquid fuel running through the motor and messing up the O2 sensor voltage.

I put an aftermarket from Jeg's on a Malibu. If you hold it up to the light, you can see through it. We don't have emmisions here. 2.5" in and out, worked great!

Dan

I had another shop check it out to look for a leak. They said there was no leak and that the sound I was hearing was just the catalytic converter. Makes me wish I had just bought a Honda one in the first place since I hate the noise.

My 02 sensors are white at the ends which means the car is running lean. They said that could be the cause for the cat dying after 4 months. It's going back to the original shop Monday and they're going to try and figure out what's going on.

I have a magnaflow stuffed under my bed right now. the Bimmer barely passed emissions two years ago and is due up in august. Unfortunately the check engine light came on for the cat AND the exhaust came apart due to rotted bolts.. so the whole thing needs to be replaced

mrsoul55 wrote: I had another shop check it out to look for a leak. They said there was no leak and that the sound I was hearing was just the catalytic converter. Makes me wish I had just bought a Honda one in the first place since I hate the noise. My 02 sensors are white at the ends which means the car is running lean. They said that could be the cause for the cat dying after 4 months. It's going back to the original shop Monday and they're going to try and figure out what's going on.

Look for vacuum leaks and dirty fuel injectors. Liquid fuel doesn't burn but it adds to the total HC as seen by the O2 sensor. So the computer keeps turning down the fuel.

I bought a "lifetime warranty" (listed as 50,000 miles elsewhere in their literature) $100 replacement for my Accord a few years ago. The factory part was ~$500. The cheap cat lasted about 3 years and 25,000 miles. After that I got the "cat efficiency" check engine light. It also had a small leak at the case seam since it was new.

I had filled out all the warranty paperwork properly, but still got the runaround on warranty. Six months later, 3 emails to 3 different people/addresses, and I still don't have an RMA. This was from ecatalyticconverter.com.

I don't remember the brand, but it is sold on a lot of sites. Just plan to replace it sooner than you might expect, and pretend the warranty doesn't exist.

I don't remember it being any louder than the factory part. The leak hissed a bit, but it seemed to stop eventually.

-Brian

Another reason I love this message board!

I was planning on dropping my wife's 2002 VW Cabrio off to have a replacement (aftermarket) catalytic converter installed today. Her car has that same "cat efficiency" check engine light on now, and we were hoping this would fix the problem.

I guess we're going to have to just step up and buy a genuine VW cat. Any idea where to get an OE Cat for less than what the dealer wants for it? Thanks guys!

PorschesOnTheCheap wrote: Another reason I love this message board! I was planning on dropping my wife's 2002 VW Cabrio off to have a replacement (aftermarket) catalytic converter installed today. Her car has that same "cat efficiency" check engine light on now, and we were hoping this would fix the problem. I guess we're going to have to just step up and buy a genuine VW cat. Any idea where to get an OE Cat for less than what the dealer wants for it? Thanks guys!

Try any worldpac distributor. I use Zygmunt Motors in Doylestown PA. (bimmerparts.com). They have online parts for everything worldpac sells, the name is just because that is the focus of their service business.

They list the OE catylist for a '90 BMW 325i $381.00, BMW wants 1150.00.

If you call them, ask for Chris and tell him Walter sent you... who knows, you might just contribute to my frequent-flyer discount :)

This thread is relevant to my interests...

Does anyone know what issue the Miata cat review article is?

Are the Magnaflows any good?

walterj wrote: Try any worldpac distributor. I use Zygmunt Motors in Doylestown PA. (bimmerparts.com). They have online parts for everything worldpac sells, the name is just because that is the focus of their service business. They list the OE catylist for a '90 BMW 325i $381.00, BMW wants 1150.00. If you call them, ask for Chris and tell him Walter sent you... who knows, you might just contribute to my frequent-flyer discount :)

Wow. They want $750 each for the cats on my 740iL (of course, that's a significant discount from the $1700 list price each). 'cmon. It can't be that much more to make an aftermarket BMW cat than an aftermarket Camaro cat.

Yeah, even if my Magnaflows only last a couple years, it'd still take 22 years of replacing them to equal the cost of one new one from somewhere else.

PorschesOnTheCheap wrote: Another reason I love this message board! I was planning on dropping my wife's 2002 VW Cabrio off to have a replacement (aftermarket) catalytic converter installed today. Her car has that same "cat efficiency" check engine light on now, and we were hoping this would fix the problem. I guess we're going to have to just step up and buy a genuine VW cat. Any idea where to get an OE Cat for less than what the dealer wants for it? Thanks guys!

The aftermarket converter probably will fix the problem, just not forever. As others have said, you can buy a few cheap ones for the cost of one dealer replacement. I guess you'll just need to estimate how much longer you'll keep the car, and how much hassle it is getting a new one put on.

My Accord cat just bolted in place, so it was no big deal to change it in the garage.

Is a car that new still under emissions warranty? They are getting pretty long now.

Good luck! Brian

Last I heard emmissions parts were covered for 7yrs or 70k miles. My dad had to get a catalytic converter replaced on a 99' Sonoma when it melted into a giant block and the truck couldn't make it up hills at more than 15mph. GMC footed the bill.

Small world. I live not too far down the road from Zygmont Motors. It's fun to drive or cycle by there and see the various project cars outside the garage..

The VW warranty on catalytic converters is 8 years or 80K miles.

all car companies are now required to warranty cats for 8 years/80k miles.

as some others alluded to, a cat failing is a side effect of some other problem, not a symptom of its own problem. it could be something anywhere from an out of whack MAF (this can be off enough to go through cats but not set a CEL) to bad rings/valve stem seals and burning oil, to a missfire/weak spark causing an incomplete burn. you need to check the other systems that could be causing the cat failure.

My wife bought the Cabrio new in 2002 and it has 94K on it now. She LOVES the stupid thing, so we're commited to keeping it.

That said, in the past year we have replaced (at the VW dealer's suggestion) to "cure" the check-engine light:

• MAF sensor
• both oxygen sensors
• idle speed motor (part of a $475 throttle body)
• charcoal canister (the little electric door didn't work)
• aux. air pump (little thingy next to the air box)
• crank sensor (part of the distributor we also replaced)
• cat-back exhaust (was getting rusty - not "check engine" light related)

The car runs PERFECTLY, has been meticulously maintained (first by the dealer, then by me) and passes emissions with flying colors. Compression is good and even among all four cylinders, there is no blow-by. We can't get an inspection sticker because the stupid check engine light won't go out.

The dealer that sold her the car said that all of the parts she's replaced are "normal wear items" and that their failure is to be expected after 90K miles of usage.

I think it's BS. I think they want to sell us a cat because they can't think of anything else to throw at the car.

Acting upon the belief that the VW Dealer in question was either ripping her off intentionally or simply throwing parts at it because they have no clue (and therefore ripping her off because they don't know any better), I took it to two other dealers and an independent specialist. All agree the light won't go out, but only two have found a cat-related problem - namely that it won't "reset" with the computer.

I think it is a vacuum leak or an electrical problem.

I also say that I would never, ever buy another VW built after 1992. The third-gen and up Jetta/Golf/Cabrio cars aren't even fun enough to be worth the aggrivation.

Jerry From LA wrote: Even an aftermarket cat should last far longer than a few months.

I have seen brand new ones clean insufficiently, right out of the box.

Jerry From LA wrote: Look for vacuum leaks and dirty fuel injectors. Liquid fuel doesn't burn but it adds to the total HC as seen by the O2 sensor. So the computer keeps turning down the fuel.

O2 sensors don't measure HC, they measure O2.

So if you have a misfire, or otherwise incomplete combustion, you have extra free oxygen in the exhaust. This gets interpreted as a lean condition, and the computer can start dumping fuel.

Good self-diagnostic setups do not check for catalyst efficiency or O2 efficiency if the engine has misfires in history.

Bad cats as determined by OBD-II are often bad O2 sensors. If the rear O2 switches as fast as the front, that means the converter isn't working... but the computer may see a slow front O2 as a bad cat.

Most aftermarket cats arent legal in california, probably becasue they arent as efficient/dont last as long. My dad took his subaru to a muffler shop and they put one on that was good enough for it to pass smog at least for about 1/3 the cost of a factory one. They said it is as good as an oem one, so we will see i guess. The cheapest aftermarket ones were around $300 and specifically not for use in california, so as long as this one last a few years it will be fine.

The VW doesn't now, nor has it ever misfired. It's just posessed. The codes that I can remember were:

MAF malfunction

EVAP system leak(s)

0xygen sensor (not sure exactly what the scanner said was wrong with it)

Camshaft sensor (defective?)

I want to put Webers and a straight-pipe on it and pull the stupid bulb. THEN I could understand it and fix it myself. I hate OBD II.

noisycricket wrote: Bad cats as determined by OBD-II are often bad O2 sensors. If the rear O2 switches as fast as the front, that means the converter isn't working... but the computer may see a slow front O2 as a bad cat.

Guess I have to try that next.. thanks!

My friend had a aba swapped mk2 gti and it constantly set cam position sensor codes. He thought it was probably a wiring problem. It could also have been related to the fact that the crank gear for the timing belt was no longer firmly attached to the crank though. lol