E36 catalytic converter options?

So, it looks like my '97 328 is going to need a catalytic converter to pass emissions. Had a mechanic quote $2600 for an installed, OEM unit as this mechanic didn't trust aftermarket units for these cars. This sounded like my cue to install one myself.

OEM ones are expensive - Pelican Parts lists one at $2000. Are there any aftermarket converters out there that hold up well? I see a lot of options out there on Rock Auto for WAY less than OEM prices.

I bought one of the rockauto ones for around 400 bucks and it passed just fine. This was on a '95 M3. We'll see about next year :P

If you aren't in California, I see no reason to buy EOM at those prices. I just sold a nice, 100% rust-free CA/WA E36 328i for less than the quote you got from your mechanic for replacing with EOM. I would get a nice aftermarket unit from Rock Auto or Summit.

On my Malibu the aftermarket one only went about 50k before it threw on the check engine light again.

There's aftermarket and then there's aftermarket. Catco is a four letter word if passing a sniffer test is the reason why you are installing a converter. I've seen them fail for NOx right out of the box. (On a car with computer controlled timing and no EGR, that isn't overheating, what else do you do for NOx?)

Have had decent-ish luck with Walker. They cost a bunch more (not as much as OEM at least) and they aren't available for all applications, as the downsides.

For my personal car, I went with a Magnaflow, because it was available and it was relatively cheap. But my car is OBD-II and Ohio doesn't smog OBD-II cars, we check for passing all the monitors. And since the rear O2 is ahead of the converter that I replaced, I installed it more to make me feel good than to satisfy HAL or the Ohio EPA.

PS - Going to be e-mailing you with more annoying questions in a week or two. Boss wants MS3-Pro on two of his personal cars and wants to know what we need to do/what the minimum order would be for a PNP box for Darth Vader's car. As well as some other orders he wants to make.

I have an E36 and I bought aftermarket Magnaflow cats last year that I didn't end up needing. I can sell one or both to you for a little less than Summit sells them for. They're still sitting in the box.

I agree with SEADave, most good aftermarket cats are 48 or 49 state legal. I think that California wants to play it safe more than aftermarket companies can't make a good cat. I have heard that cats are getting to be an old technology, something new may replace it, or automakers may not need them to pass emissions in the future.

Thanks for the feedback, everyone! Right now I'm starting to ponder if I should just get a good quality weld-in cat instead of using direct fit ones.

Knurled wrote: PS - Going to be e-mailing you with more annoying questions in a week or two. Boss wants MS3-Pro on two of his personal cars and wants to know what we need to do/what the minimum order would be for a PNP box for Darth Vader's car. As well as some other orders he wants to make.

If we've got the connector in stock, the minimum order is usually 10 units, but if it's something we were strongly considering already, it might well be lower.

And ClutchMan, you've got mail.

Mr_Clutch42 wrote: I agree with SEADave, most good aftermarket cats are 48 or 49 state legal. I think that California wants to play it safe more than aftermarket companies can't make a good cat. I have heard that cats are getting to be an old technology, something new may replace it, or automakers may not need them to pass emissions in the future.

CA wants cats to last as long as the OEM unit does. I'd be looking at why it died in the first place. Did it just age out or is some parameter (HC CO NOx) way out of whack?

Mr_Clutch42 wrote: I have heard that cats are getting to be an old technology, something new may replace it, or automakers may not need them to pass emissions in the future.

I've not heard any indications of that. Not only that, we are always trying to develop better catalysts. So I'm not sure where that info comes from.

As for aftermarket cats- I wish some of them would be a litte more open about them- but I suspect that none of them actually know what they are being sold as catalysts. There are a very limited number of suppliers for washcoat- which closely matches who markets industrial volumes of precious metals. And there's equally a very limited number of companies that make the substrates. So getting some basic info where there product comes from should be easy.

I'd like to see that, at least.

Jerry From LA wrote: CA wants cats to last as long as the OEM unit does. I'd be looking at why it died in the first place. Did it just age out or is some parameter (HC CO NOx) way out of whack?

It hasn't been put on a sniffer; I was told the O2 sensors are also apparently dead, though. The car has 250,000 miles on it, so I can believe these all died of overuse.

There was an article in GRM about cats a while back should read that.

MadScientistMatt wrote:

Jerry From LA wrote: CA wants cats to last as long as the OEM unit does. I'd be looking at why it died in the first place. Did it just age out or is some parameter (HC CO NOx) way out of whack?

It hasn't been put on a sniffer; I was told the O2 sensors are also apparently dead, though. The car has 250,000 miles on it, so I can believe these all died of overuse.

Do the O2s first. FIRST. Then worry about the cats. A lazy front O2 looks just like a bad catalyst to the computer. A lot of OBD-diagnosed failed cats are really just bad info from the sensors. That or air leaks ahead of the converter.

I've got the O2s on order from Rock Auto - we'll see how they work out.

So did you get the O2s installed?

I haven't put them in yet as the car hasn't thrown any codes since the evaporative emissions repair.

I cut the pipe and welded a Magnaflow universal (IIRC $80?) one on my friends '95 M3 and it passed a NJ emissions inspection no problem. This was a few years ago, they are probably $100 now. There were a number of configurations so make sure you match the in/out sizes. Since you probably have an OBDII car stock exhaust you need 2.

I might have a mid-pipe with good cats in my garage if you want a used one. I'll have to look to see if it's OBDI single or OBDII double. send me a pic of what you have now so I can match it up if you are interested.

I have had one from Random Technologies on my Focus since 2003. It passed the MD sniffer test just fine before they went to OBDII plug-in. It has been tested every 2 years since I put it on.

It doesn't look like they have a direct fit replacement for BMW but they do have universals. Also they are located in Loganville, GA.