Waterguy

Was this originally a California model? California had (has?) stricter emission standards than the rest of the USA, so our 951 DMEs contain California-specific maps. To convert from rest of USA to California emission specs, you need to add a jumper (coding plug - 944.612.525.01) to the DME wiring harness. There should be two open sockets on the DME wiring harness a few inches from the DME connector. The coding plug goes into the first open socket.

This won't help with a bad cat, obviously.

hansman

Excellent point..........
I can only speculate here but you may be on to something.
How does one find out whether or not it is a California model?

400hp944

I just went through all this back in October. I feel your pain. After 3 attempts, Jeff at Black Forest said to try the Race Fuel. Worked like a charm.

Did you put all your stock crap back on before all this?

Loquat15

IF you do end up getting a cat, have it designed in such a way so that you can remove it and install a test pipe in its place so that you can store your Cat and not destroy it. Although then you wouldnt be street legal and could get a ticket, however i've never heard anyone getting ticketed for something like that.

My OEM cat is waiting for next november... we'll see what happens :-)

quinnfiske

I had a hard time here in Wisconsin. We have an IM240 dyno test that runs the car at various speeds. I finally passed with the original cat (178K miles). I ended up replacing the O2 sensor, DME temp sensor and dialing in the idle fuel mixture at the AFM. I think that a previous owner/tech adjusted the AFM with an old O2 sensor, so it failed when I replaced it. Just a guess.

biggles

Reduce boost and add a bottle of octane booster. Worked for me in Texas after a hot few miles. Also, go back before due date and do a prelimanary test.
good luck!