ROG100

I do not think ite cats never heard of a failure before.
New MAF on the way so we can check that out.

RED SHARK 1990

Hello ROG anyway there will always be the first of anything dont say never.Parts failed even like new knock sensor or tps sensor new so often we have heard its new.But they do failed...Lets see..ROG

jorj7

Roger,

My Random Tech Cats failed the first time I tried a CA smog test with them. My
stock cats also failed the CA smog test. I had to install a known good cat to
pass... So it does happen, at least here in California (a lot!).

ROG100

I stand corrected

blown 87

When we replace cats at our shop with aftermarket ones, I tell the customer that they need to be ready to replace them every year or two.

There is a reason for the very large price difference in after market and factory cats.
Even after they are bad, I have seen defective MB cats go for over 300 bucks each, and aftermarket ones you are lucky to get 20-30 out of them.
There is more precious metals in the factory ones, or so I have been told.

We have the same test on pre 96 cars in Georgia as far as what comes out the tail pipes as CA does.

RED SHARK 1990

Alright tonight i installed a rebuilt maf ,new air filter and a new o2 sensor .Tomorrow a set of CA cert magnaflow cats made for the 928 to be installed and i hope that will solved the problem....

ROG100

I hope you pass. Unfortunatly you will probably not know what the cause was. At least with the MAF we can send it to JDS and have it tested.
Fingers crossed for you Luan.

blown 87

If it still fails on just NOX, you can hook up a 20 OZ soft drink bottle with a restriction of about .020 or so and fill it with water to use as a poor mans water injection to cool the combustion chamber to lower NOX for the test.
Just hook it up to a direct vacuum source.

ROG100

An interesting discussion taking place on one of the European forums about the same subject. IIRC the regulations are even more stringent in Europe (particularly Germany) than CA.
Disconecting the airpump or bypassing the diverter valve to stop air being pumped into the cats is the difference between passing and failing.

blown 87

The AIR pump in the 928's must work different than the cars we work on.

Most of them only come on for a few minutes after starting to get the cats up to temp quicker, and some times they are used during de-acceleration.

Are they testing for secondary air injection reaction pump operation?

I am missing something here as to why they would fail with the air pump not working on a hot car during a sniffer test.

Bill51sdr

+1. The air pump is only used to warm up the cat on cold start, nothing else. After that, the pump output is diverted to the airbox/atmosphere. However, if the diverter valve is malfunctioning you could theoretically get constant air to the cats. It's been my experience that this will result in a cherry-red cat at times.

Mongo

I'm waiting to hear about this smog update.

The air pump on my car is not hooked up at all to my aftermarket cats due to no air inlet and they passed me in San Diego with flying colors at half of the max allowed in CA.

I hope I'm just as lucky this year in the Bay Area...

Bill51sdr

Didn't I warn you about this??

dprantl

Are you sure about that? I saw my friend's report from CA for his '97 SAAB 9000 CSE a few years ago and the HC limit was unbelieveably low, something like 20 ppm (yes, TWENTY).

Oh, duh. I just noticed your post said pre '96.

Dan
'91 928GT S/C 475hp/460lb.ft

Chris

Good luck with your retest, I just came back from the station with my 87 with x-pipe, no air pump and high flow cats that are over 2 years old. Passed just fine, note we only test for HC and CO up here and the car JUST fails with no cats.

Chris