Mister Quickie

A remanufactured OEM catalytic converter is over $1000, more than the car is probably worth if I do two. A Universal catalytic converter is around $100 each. As long as I match the pipe size of the exhaust is there any reason not to use the Universal catalytic converter? By the way this is for an Audi A4 B6 B6 Cuatro

Van

I put a $79 Magnaflow universal cat on my 944. Seems fine.

odonnell

(There are forums for those cars too)

A cat is designed to interact with exhaust from a gasoline burning engine, with exhaust properties that are consistent with 99.9% of cars. It will be fine.

V2Rocket

here is a direct-fit piece for your car for $270
http://www.rockauto.com/en/partsearc...nverter%2C5808

SloMo228

Uh oh, someone mentioned Audi on a 944 forum.

But yeah, to answer your question, a universal catalytic converter can be used no problem. Just match the pipe diameter, weld it on in the same location, and away you go. This doesn't address any legal aspects (such as having to have a CARB-approved conveter if you live in California) but functionally, a quality aftermarket converter will do exactly the same job as the OEM one.

I have an aftermarket "high flow" converter on my 944S and it works just fine. Got rid of the exhaust stank that was a result of the PO putting a straight pipe in place of the OE converter.

marc abrams

I agree with Spencer on this. Get the direct fit cat and save a trip to the emergency room.

Perry 951

I've worked in the repair industry for a very long time and have a bit of experience to share on OEM vs Universal converters.

If you see a direct fit that is OBD2 compliant, it is a toss up if it will actually function like an OEM converter. Universals that are non OBD2 compliant most certainly will not function like an OEM.

What we see on a pretty regular basis is.. on OBD2 vehicles.. more often than not, the universal cats do not have enough catalyst material (the expensive metals) to keep the rear O2 happy. This in turn keeps the check engine light on. In areas where smog testing or OBD2 compliance is required for inspection, the car would fail. For non OBD2 cars and for people who don't care about the light or the possibility of increased emissions, the universals will pass the look test for inspection.

pdxfj

When I bought my 944 it had a straight pipe in place of the cat. I went to a local muffler shop and they installed a universal one. I remember them telling me since it's an '86 I didn't need to spend the extra on an OBD2 compliant CAT. Don't remember what the cut off date was for an older style CAT vs a new one.

My car has passed local emissions testing two times since then without any issues.

Jfrahm

If the cat is working well enough to pass smog but just throws codes you can spacer out the rear O2 sensors with spark plug anti-foulers. Cut the element cover off the planar style sensor if needed to fit. It might also be possible to switch to the skinny ND style O2 sensors or to hog out the anti-fouler body. *My friend* found that cutting the cover off the planar style sensor was easy enough with a dremel. Just cut off below the threads to expose the element.

flashx

The trick you are talking about works very well. It spaces the 02 sensor out of the main stream of exhaust. What I have done s drill out the center of one oil fouler to 1/2 in inside diameter the then the o2 screws into that. It works like a charm in fact if you go that route you shouldn't even have to change the Cat

SloMo228

That's a good point - the cheapo universal ones don't work as well as quality ones with an adequate amount of catalyst.

You just can't make a catalyst which requires platinum for cheap - if your converter is $50, it's because the manufacturer skimped on catalyst.

Mister Quickie

I have no idea how to do that but if it were just to suppress the CEL, couldn't I just remove the 02 sensors from the cats and tie them someplace out of the exhaust stream?

The next questions though is since I only have to pass emissions every two years (no safety inspection) and to do that they warm up the car and rev it then plug some tool in the tailpipe and run a test, if the cat isn't properly cleaning, is there another way to pass the test just for that day? I've heard people say there are liquids you can put in the gas tank to get you to pass but I'm leery of doing that

Jfrahm

No, you get a CEL for anything but an O2 sensor in place and the sensor heater drawing current and it sending a plausible signal and that signal being a reasonable derivative of the other O2s, and other factors such as engine temp.

The spacer trick works when the cat is working well enough to pass smog but not well enough for the ECU to feel that everything is working properly. The spacer on the rear O2 makes it look like the cat is working really well when it might be only working at 50-70% or something.

You might have other issues causing the poor cat performance (bad O2s, bad fuel pressure regulator, etc.). If the cat is not working well enough to pass smog you need to fix that and probably whatever is killing the cat unless it's just old and wasted or poisoned from oil smoke or something.

You can post your OBD2 codes if you like and we can take a look at them.

-Joel.