I need help/advice on how to clear the sensors on my (newly acquired) 993 Turbo so that I can get it smogged. The car has sat for a long time and the battery may have been disconnected at some point. At the suggestion of the smog shop owner, I drove it on the freeway for about 30 miles, but when that didn't work, he said to drive it 100 more miles and come back. Kind of feels like I'm shooting in the dark... Any suggestions or insight would be appreciated!

 

Do you have a check engine light / fail, or was there some other reason?

Unfortunately, there is tons of info on this subject here if you search for "CA smog" and "California smog."

I put in the Techron black bottle FI cleaner before any smog check for good luck.

 

Thanks, I'll do a search. There are no check engine light issues; the sensors just aren't sending data to the smog check computer...

 

You may mean that you have to reset the flags. There is a specific drive cycle to reset the computer. Check out this thread:

https://rennlist.com/forums/showthre...ferrerid=71740

Also do a search on BMW drive cycle. Good luck.

 

There is a specific drive routine to follow to get all the register in ready state. In CA, you are only allowed for 2 registers in "not ready" state to pass. I have an OBD reader and I work in San Mateo if you need a reading on your ECU.

 

I had similar issue on my 97 Lambo, battery was disconnect for a month or two, car passed the sniffing part, but the 02 sensors were not ready or (not on line)
I was told by the smog tech the same thing, drive steady no more then 60mph for 20-30 mi and bring it back.
Well that did not resolve anything.
My Lambo had to go through 3 heat cycles, meaning you drive the car park it and let it fully cool down, and go through the warm up process. (Three times)
I’m not 100% sure if that is the same for a Porsche but that sure took care of my Lambo’s readiness code.

 

key search terms for your issue = "readiness codes"

https://rennlist.com/forums/search.php?searchid=5527581

good luck

 

call rich walton at jerry woods enterprises in campbell...

he took my car through to reset codes and then pass smog.

my 2 cents

 

Call Tony at Heyer Performance in Mountain View, 650-962-0930. He can reset everything and send your around the corner for a smog certificate... as long as there is nothing truly wrong with the car. Great guy, great shop!

 

In short;

Here's the simple version:

Start engine, let idle for approx. 2 min, 10 secs.

Accelerate to 20-30 MPH, Maintain steady speed for approx 3 min, 15 secs.

Accelerate to 40-60 MPH, Maintain steady speed for approx 15 mins.

Decelerate and come to a stop. Then:

Idle in Neutral for 5 mins. (manual trans.)

Idle in Drive for 5 mins. (Tiptronic trans.)

During the drive cycle, do not exceed 3,000 rpm or 60 mph.

 

Guys, thanks for all the great suggestions and leads...I'll give these a try and take it in for a re-test on Saturday, and I will let you know how it goes...

 

Before he attempts a full re-test, ask him to plug in the electronics and see O2 sensors and whatever that is throwing the codes are ready.

 

I bought an OBD II diagnostic tool, and it took two drive cycles for all of the monitors to run their routines and come online, but I followed the steps below, and I can attest that it worked (like magic)!

1) Start engine, let idle for approx. 2 min, 10 secs.
2) Accelerate to 20-30 MPH; maintain steady speed for approx 3 min, 15 secs.
3) Accelerate to 40-60 MPH; maintain steady speed for approx 15 mins.
4) Decelerate and come to a stop.
5) Idle in neutral for 5 mins. (manual trans.)

I was never so happy to see that yellow light on the diagnostic tool change from yellow to green! I'm in Los Gatos, and if anyone in the area encounters a similar problem, I would be happy to help... Dean

 

Been there, done that! Great feeling, congrates.

 

I went through the same thing on my '96 C4S. Call the DMV and make an appointment with a Smog Referee Station. 1-800-622-7733. Explain that the car passed the emissions part but the computer isn't ready due to the battery and/or car sitting for a long time. They'll have you bring the car in, inspect it, and pass it.