Catalytic converter STINKS!!

[Bravo]

I have a 1994 325i and the Catastrophic converter is really starting to smell like rotten eggs. Does this mean it is going bad and plugged up? How much is this going to cost?

Thanks,

Dean

[Jared at Pelican Parts]

Sorry to say, but usually a sulphur-like smell indicates that the cat is going out. Replacement involves cutting out the old cat and having a replacement cat welded in place. I'm not sure off the top of my head how much the labor is, though.

[JasonBMW]

Aren't there two cats on this car? I think that there are on my 318.

[Bravo]

Thanks for the responses. I called a local muffler shop today and inquired about the cost of a replacement and he asked me if the car had a loss of power. I said no and he asked me when it smelled. I told him that I mostly noticed it when I get home and pull in the garage. Then he asked if I go up any hills? I said yes that I go up a windy 1 mile hill to my house. He said that when you go up hills the car is dumping too much raw feul into the intake and the smell is the converter doing its job. I told him I appreciated the honest answer and that was it. Has anyone else heard of this? The loss of power makes sense but the hill thing??? btw it does not smell at any other times

Dean

[Wayne 962]

That's almost 100% bull (in my opinion). If your car is operating correctly, the mixture going into the cat will be the same regardless of the load placed on it. The mixture is controlled by the Motronic engine management system, which dynamically tunes the car for a variety of conditions, based on feedback from various sensors. If one or more of the sensor (like the o2 sensor) is bad, then the car will run rich or lean.

What you really need to do (instead of listening to someone 'guess') is to take the car to a friendly shop that will allow you to check the mixture. This will tell you firsthand if the car is running rich.

CATs don't typically fail on their own - they are usually hurried along by a rich-running car that dumps soot and raw fuel into the CAT. This is what causes the cat to clog. Placing a new cat on the car without fixing the original problem will lead to premature failure of your new cat. The cat should be the last thing to be replaced when you've done repairs, because if the mixture is bad, you will ruin your new cat...

-Wayne

[Dave at Pelican Parts]

Actually, the mixture does change when the engine is loaded "enough". If you're running up the hills at wide-open throttle (WOT), usually the feedback mechanism in the Engine Management System will be disabled and the mixture will be fairly rich. Ditto if you keep pumping the gas pedal; most EMSes will richen the mixture when the throttle goes from less-open to more-open to help acceleration.

But if you're cruising up the hill at a steady part-throttle, the mixture should be fairly near stoichiometric.

The rotten-egg smell is sulfur. Among other things you can try, another brand of gasoline might help. I recall that Chevron and Shell were rumored to be relatively high in sulfur content, but that was just a rumor that I have not been able to verify.

I agree with Wayne, though--find a way to check your mixture and see what that has to tell you. Catalytic converters can indeed fail without blocking the exhaust (to the extent that you will notice just driving around on the street) so the "does it make less power?" test is not definitive.

Of course, you could always wait until you have to pass some emissions test....

--DD

[Wayne 962]

Okay, I re-read your post, and I semi-retract my statements. Maybe not 100% bull - I didn't read carefully that part about the hill, right before your house. True, if the car is dumping fuel, but running at low RPM, then all of a sudden shut off, you may have that smell (I suppose).

Still, I would have it checked out with the scope - it won't lie. Also a code checker will tell you if the scope reading is going to be off...

-Wayne

[Bravo]

Thanks for all of the responses. A couple of points. I do use Chevron Gas and yesterday I filled up with premium to see if that would help. secondly I am often driving pretty spritedly (sp) up the hill to my house. (you know just getting out of trafic onto a relatively quiet road - sometimes the ponies need to run! so I am on it pretty good

but today I am taking it to my local shop to have it checked out and I'll have some answers later

Dean

[Bravo]

Wayne do you selll the converter for my car? And also do you sell the computer to reset the codes?

Dean

[Wayne 962]

We'd have to special order the converter - they have to be sold through CARB-approved places, etc.

As for the tool, here it is:

http://www.pelicanparts.com/cgi-bin/autocat/load_page.cgi?page_number=1&bookmark=1&model=BE12&currsection=electr

Hope this helps, the tool is very, very useful.

-Wayne

[Bravo]

Ordered the Gadget and the Bently manual from you this am Thanks

Dean

[Wayne 962]

You should not be disappointed. Although the Bentley manual is lacking, it is the best source out there right now (until 101 Projects comes out!)



-Wayne

[umnitza]

this *might* help.

I don't know when it began, but our E38 had it's cat replaced under an 8yr/80K warranty.

You *may* fall under that - but most likely your mileage is higher.

[Bravo]

Good Idea, my mileage is 71k so if there is some type of Warrenty I would probably qualify. I am going to call the dealer today

Dean

[umnitza]

beg then, because a 95 is 8 years old, yours is a 94

[umnitza]

but it's date of purchase I think

[Bravo]

aaaahhhh! good point I guess well see!

Dean

[Blackfoot]

i have a '92 325i that needed a new cat 6 months ago. ours is a dual-style, and at a muffler shop set me back $700. that was for a "universal", non-oem cat.

[Wayne 962]

Yikes, you're right - retail for the aftermarket units are around $700!

-Wayne

[Kelley Brown]

You are going to need a new CAT or I heard you can try to clean it or remove the insides. I am looking for help with this myself!


Kelley Brown

kelleybrown1@comcast.net