Barring the normal issue of visual inspection, and saying that the visual is hypothetically removed from this equation -

Has anyone passed "rolling road" smog with no cats on an S3 or S4?

 

i passed with a racing cat from magnaflow...... ofcourse the inspector was a Korean who spoke no english, let alone could read the German under the hood.... :-)

 

Not possible in California, that is for sure.

 

I know someone who passed CA smog in a VW Vanagon with a gutted cat. That was probably about 8 years ago, but it passed smog well within limits.

 

In CA, can you pass with race cats? If they spot aftermarket cats on the visual is there an issue even if it meets standards?

 

yes, my 84 passed with no cats back in the day where they might be too lazy to look for the cats on a near stock car.
it was funny to see the gross change in the levels of polutants, but it passed.

 

You will be failed on visual unless the aftermarket cats have a CARB ID that matches the list of what they can be used on. That's one of the best reasons to keep the belly pans in place IMHO. What they can't see won't hurt them.

My 'inspector' looks, scratches his head, and ultimately asks if anything has been changed. He can't seem to get a timing reading since #1 wire is so short, gets lost with the vacuum diagram and all the hoses hidden by intake manifold and fuel rail covers, and can't seem to ID the air pump unless I point it out to him. So he just asks. And this is a claimed former 928 owner, at a test-only station.

My S4 will not pass without cats. NOx is too high in the under-load tests. MK's success probably happened in the pre load-dyno days of Cali inspections. In those days, the tech just raised the engine RPM with no load, so NOx wasn't an issue on the 928. Now, the autobox rolls through the gears quickly with the light loading, and the sniffer looks at gas composition. It only cares if the engine RPM's are too high.

 

I passed with $50 race cats, metallic cores too. Got them from Performance-Curve.

 

Thanks Bob. NOx is a function of combustion temps if I recall correctly, and one may be able to reduce those NOx numbers with some other fuel, possibly the fuel made from *corn* (I didn't just say that).

Its tempting. I have a smog guy that does not check for cats, and the rest of the car is stock including the air pump. I am contemplating trying it on the 86.5 to get it registered legally and clearly titled here in CA.

Further, if there are "bumps" in the pipes after the H-pipe area, then that would also suffice if he looked, no matter what the bumps were.

I am interested in Andy's usage of "race cats" as a cheaper alternative.

 

I live in Michigan, what's a smog test?

Rhetorical...

 

All it takes on a pre 96 car is a hundred bucks, or so I hear.

 

Depends upon the age of the car.

 

Why would you have cats on your car? The leave all those dirty footprints everywhere. The cows here cause more environmental damage than the cars.

 

They lick the pollutants clean.

 

Here's the Magnaflow list of CARB approved cats. Absurd that they differentiate 85-89 and 90-95, but I won't complain, 'cause the 36304 has no provision for the air pump injection tubes, while the 36014 does.

'Yes sir, that's the CARB approved cat for a '93, yes sir!"