Failed smog check due to OBDII
08-25-2004, 12:21 PM
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Failed smog check due to OBDII
Hi all,
I have a stock 96 993TT which I took to get smogged. It passed the emissions test with no problem, but failed when the OBDII was connected. The reason I was given is that the OBDII had not done it's system check. He thinks that perhaps the battery was disconnected during some recent repair work and that the car needs to be run for a specific amount of time at various conditions for it to perform these checks. The car usually sees freeway driving of around 150-300 miles/week. I don't recall having any recent service that would have required the battery to be disconnected. I have had the car on a trickle charger regularly because the battery use to die if not driven for 2 weeks, but I got the charger months ago and haven't had that problem since. The mechanic thinks I need to do some more city/stop and go driving to get the system to reset and perform it's diagostics. Does this seem to make sense? Could the trickle charger have something to do with this?
Thanks in advance,
Anthony
I have a stock 96 993TT which I took to get smogged. It passed the emissions test with no problem, but failed when the OBDII was connected. The reason I was given is that the OBDII had not done it's system check. He thinks that perhaps the battery was disconnected during some recent repair work and that the car needs to be run for a specific amount of time at various conditions for it to perform these checks. The car usually sees freeway driving of around 150-300 miles/week. I don't recall having any recent service that would have required the battery to be disconnected. I have had the car on a trickle charger regularly because the battery use to die if not driven for 2 weeks, but I got the charger months ago and haven't had that problem since. The mechanic thinks I need to do some more city/stop and go driving to get the system to reset and perform it's diagostics. Does this seem to make sense? Could the trickle charger have something to do with this?
Thanks in advance,
Anthony
08-25-2004, 01:21 PM
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I drove my car for months after a battery disconnect and it wouldnt pass. Search this topic in the archives and you will find the procedure to "ready" the car for inspection. I followed the annoying steps (like not going over 3000rpm--that one was next to impossible) a fellow renner listed, and in 30min or so my car was "ready". These kind of tips make the membership to Rennlist a steal.
08-25-2004, 08:15 PM
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Make a appointment at a referee station. The 1996 993 is in their book as one of the cars they will let slide if the ready codes are not set. FWIW the 1997 ECU has less of a problem learning. I have drove less than 75 mile on the 1997 ECU and the ready codes have set. This was not the case with my 96 ECU.
09-04-2004, 09:55 PM
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Drive cycle to pass OBDII
Here's the drive cycle that works to reset the readiness codes:
1. COLD start, Idle for 10-15 min.
2. Drive at 2200 RPM for 6-8 miles.
3. Drive at 2500 RPM for 4-5 miles.
4. Drive at 1800 RPM for 6-8 miles.
5. Let idle for 3 min.
This cycle worked for my 96 993TT. The Porsche mechanic who gave me this sequence, told me that it may have to be run twice. I ran it once and it worked!
It's difficult to find a safe place to do this run and I tried another drive cycle posted around here, but that didn't work. You cannot exceed 2800 RPM at any time during the cycle. I hope this is helpful to someone.
Regards,
Tony
1. COLD start, Idle for 10-15 min.
2. Drive at 2200 RPM for 6-8 miles.
3. Drive at 2500 RPM for 4-5 miles.
4. Drive at 1800 RPM for 6-8 miles.
5. Let idle for 3 min.
This cycle worked for my 96 993TT. The Porsche mechanic who gave me this sequence, told me that it may have to be run twice. I ran it once and it worked!
It's difficult to find a safe place to do this run and I tried another drive cycle posted around here, but that didn't work. You cannot exceed 2800 RPM at any time during the cycle. I hope this is helpful to someone.
Regards,
Tony
09-04-2004, 10:56 PM
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Tony,
Thank you for posting that. May come in handy, since I just ordered an OBD-II reader from Auterra to check a repeating CEL (which I recently reset by disconnecting the battery).
LOL...I couldn't help but chuckle because the drive cycle sounds like a recipe for the dreaded carbon buildup problem.
Thank you for posting that. May come in handy, since I just ordered an OBD-II reader from Auterra to check a repeating CEL (which I recently reset by disconnecting the battery).
LOL...I couldn't help but chuckle because the drive cycle sounds like a recipe for the dreaded carbon buildup problem.
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09-04-2004, 11:25 PM
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I had same the problem with my 993TT. The codes wouldn't reset, even after trying all the remedies my shop could think of, and that I found on rennlist. I ended up going to a referee station, and they passed the car without a problem, even though the codes would not reset.
I don't know how anyone can do the specified reset cycle driving, unless they have a very long open road with no traffic. Avoid the pain and just go to the referee station. I went to one at Los Angeles Trade Tech, and all the guys in the large garage came over to gawk at the car. Almost all of the cars they were working on were beaters, so the 993 really stood out. They even took a photo of the car for their scrapbook, as they said they get a lot of exotics in for smog checks, and they keep a scrapbook.
I don't know how anyone can do the specified reset cycle driving, unless they have a very long open road with no traffic. Avoid the pain and just go to the referee station. I went to one at Los Angeles Trade Tech, and all the guys in the large garage came over to gawk at the car. Almost all of the cars they were working on were beaters, so the 993 really stood out. They even took a photo of the car for their scrapbook, as they said they get a lot of exotics in for smog checks, and they keep a scrapbook.
