STLPCA

From another thread:
This has become a commonly mentioned point. Does anyone have any meaningful data on the numbers or percentages of OBDII 993s w/this CEL problem?

Those on the board that have the carbon problem are understandably upset & quite vocal, but in total represent a statistically insignificant number of cars. I've not had any CELs at all in my daily urban driving. FWIW, my Porsche dealer has yet to see this issue on a 993, but maybe we in the Midwest just drive 'em like they were meant to be driven.

I'm curious IF this is the widespread problem that many posters seem to suggest.

Dave Crellin

You raise a great point, and I say that from a position of having spent many ,000's of $ on this problem.

I have no statistics but my local independent shop (RedLine) and Mike Schatz at Rusnak in Thousand Oaks had seen this before they saw my car and diagnosed the problem. I understood it to be more prevalent in Tiptronics where revs tended to stay lower, and esp in those that saw lots of heavy traffic. This could elevate the incidence in Los Angeles, I'm sure.

Rezal

Poll time? Not statistically accurate but better than speculating. I apologize if my quote above exagerated the facts.

Ron

Hi Dan,

I don't know if this is a widespread problem or not either; really only time will tell as the cars accumulate miles.

What I concerns me or should I say interests me is whether or not a design flaw exists relating to the air injection ports. I am not an expert so I can not offer an opinion one way or another. My information relative to the issue has been from my research of the opinions offered by others on the Board and from emails from folks who seem to have a handle on the issue.

The following seems relevant and worthy of comment; I do not take credit for this analysis, it's from a fellow Rennlister who knows far more about this issue than I.
1-Carbon blockage issue is the result of the buildup of carbon in the air injection ports,
2-The purpose of these ports is to lean the air fuel mixture to reduce emission during the first two minutes after start up as mandated by the EPA for all '96 year cars and newer equipped with the OBD-II systems
3-European 993's do not have these injection ports as they were not required for reduced emissions.

If 1-3 above are correct. The question is why did Porsche design and manufacture the the air injection ports in such manner so as to allow them to become blocked by carbon buildup sufficient to trigger the CEL?

David '96 993

Statistically speaking, I do not have any data on prevalent this problem is. What I do know is this:

1) It is frequently discussed here and quite a few Rennlisters have experienced this problem (myself included).
2) The local dealer has "resolved" ($$$$) this problem on many cars, but would not divulge how many. One was being serviced with this very problem one day I was in discussing this issue with the service manager.
3) Every shop that I have discussed this with (5) has had first hand experience with this and have had to clean the ports.
4) It has been discussed on more than one occation in Panorama and Joel Reiser is very informed on the subject.
5) PCNA is very aware of the issue and has well documented reasons as to why this is "not a warranty" issue, but rather a "wear and tear" issue.

I have tried talking to PCNA, the local Service Manager and the Regional Service Manager and each time it has resulted in a dead end. Currently, I do not know what my next step would be except to contact the EPA and discuss the issue with them to see if the burden of this recurring issue is the vehicles owner or the manufacturer. I need to educate myself further on the laws regulating this.

Randy M '96 Silver 993

All I know about the issue is that my car has it and my Mechanic tells me he can try to fix it for $1500, but if that (low cost) solution does not work, the full solution ($3000) would have to be performed.

Luckily I do not need a smog check for a while!

STLPCA

It seems to me that IF it can be established that this is a statistically common problem, you'll have a far better likelihood of attracting the interest of agencies, or maybe even PCNA. Right now, you are isolated voices in the wilderness. No one seems to know if this effects dozens, hundreds or thousands of 993s.

From my layman's perspective, it seems that w/enough data & some analytical skills, it may be possible to focus in on driving habits, gas composition/quality/regional mixes, engine # ranges, etc. as contributing factors. Candidly, not having experienced the problem (yet???) I'm not emotionally or financially invested enough to undertake such a study. However, this is the stuff the internet & this forum makes possible.

Anyone with the interest & skills to set up a website to collect such data?

David '96 993

Are there any polling tools on the Rennlist besides posting it as a topic and having individuals reply? I want to make sure that this gets as widespread an audience as possible.

Also, anyone have any ideas on how to contact PCA members to poll them as well?

I do not think that I would successfully get any data from dealerships as this is currently a cash cow for them.

I will try to contact EJ and see how he was able to put some statistics together when he was working on the wiring harness issue.

Randy M '96 Silver 993

Let me know if you need help with the data gathering.

993MSJ

I have a 97 Tip. C2 with the dreded Carbon problem Daily driver. Heavy Miami traffic. My local dealer refuses to even consider any repairs under warranty on this item.. It really stinks.. I have just ordered an RX-8 to use as my new daily driver, my love for Porsches is falling fast. Double drivers side door click, noisy windshield, CE/carbon, for German engineering it is a total dissapointment. I still love the look of our 993. I also had a 90 C2 Cab. which also had certain problems. My wifes 1999 Land Cruiser just went over 65K, with the ONLY problem being a faulty starter covered under warranty.. Now, THAT is reliability !

DrZ

I have a 97 Mercedes E420 with a clogged air bank which tripped the CEL at 80K miles. Dealer quoted me $3k to "fix it" no help from trhe regional mgr. CA emission sys warranty void over 70K miles. I currently have 120Kmiles 90% of which are freeway cruising at 75mph, techron before every oil change, and the tank has only seen Chevron 91. I pass smog test by yanking the pos. battery wire to reset the computer.

Posting this info to demonstrate that this problem is not confined to P-cars and may be independent of driving habits, techron, etc. Also appears to be a common topic on the MB board. Maybe this is commom to all German imports from this era?

csertich

A newbie question on this topic. Is the potential for carbon build up greatest during the warm up cycle via the operation of the air injection ports? Would it better to start your car and slowly get it moving right away (goes against my grain to do that) so revs go up at least a little bit during this two minute cycle? Any chance of reducing build-up this way?

You veterans are certainly allowed to send this to the stupidest question pile, if that's what it is.

But I felt qualified to comment because my '96 M3 and '89 Landcruiser have flashed their cel's so many times, friends all over the city refer to the cel now as the chuck engine light.

chuck

P.S. I thought I'd lost my passion for driving (M3 was boring!). And then three months ago I got a 96 993 Polar Silver/Black. Great options. Enough said.

GratefulJED

I have a leaky exhaust valve on my tiptronic with no CEL. I would say that the tips do tend to drive in much lower rpm's which certainly would lead to the problem, IMHO. The PO probably went from "D" to redline without much thought about it - mostly drove in "D".

Kevin Reilly

My '96 had its first "air induction port" CEL a couple of weeks ago. Light came on at freeway speed, roughly 65 mph in 4th gear. I think I was easing off the throttle to get into a turn off lane.

Car has 42K, driven mostly at highway speeds. Very little idling and not used for short hops around town. Techron used before every oil change.

Last year I went through a one-month period of CELs from random misfires. There has been no repeat of that in quite a while.

I have to do a smog within the next month, so I am hopeful that I don't get any more CELs (knocking on wood).

IIRC a few months ago Excellence featured a 993 buyers guide article, and they mentioned the carbon buildup problem and CELs as a common occurance with these. Said it was a $4,500 problem for the valve guides. Out of 3 cars they looked at for a prospective buyer, 2 had CEL problems. So I don't think this is a problem that effects only a small number of 993s.

tom_993

Hi Chuck,

IMHO, warm-up time has nothing to do with it. The pump is operational during warm up, so it’s pumping fresh air through the ports and into the exhaust. It seems to me this would actually prevent carbon build-up in the ports. It’s when the pump turns off and exhaust gasses can go back up the ports that the build-up occurs.

I wonder what would happen if the pump were on all the time? Just run a wire from a 12V source to the pump. Would the fresh air going through the ports all the time prevent the build-up? Would there be any downside? Perhaps burning out the pump eventually (but that’s got to be cheaper than the port cleanout). Or maybe over-heating the cat due to the extra O2?

Tom
’95 993