I have a 1995 993. (Sorry folks, nothing exotic. Just a Carrera 2)
I tried to pass smog the other day after a long time in storage. Prior to trying to pass (CA) smog, I changed the cap and rotor, replaced the plug wires, spark plugs, fuel filter and probably some other things I don't remember. Everything is OEM except the plug wires, (Beru). Drove it around on the freeway for over 20 miles to get it hot. It failed. The slow speed (15mph) HC failed. It registered 92 PPM. Maximum allowable is 59. Average is 15. The high speed (25mph) HC passed ok. It was 28 measured. Allowable is 35. Average is 11.
So, took it home and put some rislone pass smog stuff in it. The directions say to add it to a 1/4 tank. Drive it till it's almost empty, put a full tank of fresh gas then take the smog over again. So I did. This time drove it for about an hour on the freeway prior to testing. Results were a little better (85PPM), but still failed slow speed HC. I think I replaced the o2 sensor about a year or 2 ago. And I have a book of receipts but can't find the one for the o2 sensor. I've heard that an oil change can help? So I went to the dealer and ordered a new wheel lock key (You Have To take the car in so they can try different keys) so I can change the oil (Access the rear filter). I would Really rather not have to replace the very expensive cat. Short of all that, any other suggestions? And is there any way for me to test it before taking it to the smog guy?
The smog tech said this means it's running rich?
Also, any Good, Knowledgeable (with older 911) smog techs with the working equipment to do smog checks in the SF bay area (East Bay) you can recommend? Although this guy only charged me $42.50 for the restest because he did the first one ($90). So I am not complaning. Thanks.

 

Before you replace cat conv get it on a puter to see if when it drops into loop mode if it is running rich…if it is, check injectors for one or more not metering properly and if all ok replace ox sensors.

 

Wow. Big thanks for the quick reply GT3 Chuck!
"get it on a puter to see if when it drops into loop mode if it is running rich" How do I that? Who has that type of software?

 

Any Porsche independent or dealer should have the ability to check individual injectors and air/fuel at ox sensors to see if running rich…thinking it could also be pcv problem. Although cat conv is primary suspect I would want to clear the injectors and smog pump (pcv valve) first to make sure it isn’t just running rich.

 

Awesome. Big thanks GT3 Chuck. I'll call around on Tuesday (Monday holiday) when hopefully everyone is open again. Thanks again