glenn993

My 911 has clogged SAI ports, code 1411. Since this happened, I've learned a lot about this from this wonderful board, my mechanic and the Internet at large. Here's what I think I know:

1) This is clearly a design defect that will eventually result in BIG problems for every NA 993 owner.
2) The "official" word from Porsche (via dealers at least) is "take apart the engine every time this happens."
3) There are several alternative fixes:

1) Partially disassemble the engine, flush the system and hope for the best.
2) Bypass the ports with plumbing to the cats.
3) Modify the circuit and fool the ECU.

There is tons of information on the first 2 alternate fixes - although the plumbing bypass seems to still be evolving.

But there is almost no information on the circuit modification, which is probably the most effective, least expensive solution. I found this thread:
https://rennlist.com/forums/993-forum/12584-bypass-circuit-for-check-engine-carbon-build-up.html and was able to dig up a schematic, but very little else.

So, here's my question:

Why, when semi obscure things happen to our cars, does this AMAZING community have detailed, knowledgeable information - often step by step fixes with photos (thanks BobbyT, etc!), but when this huge, common (unavoidable) expensive problem happens, there is almost no info on (arguably) the best solution?

I would expect people selling kits, or at least a build log from someone. I've PM'd and emailed several people who posted on that thread or seem knowledgeable or otherwise informed. I get crickets.

I'm not a conspiracy theorist, but it sure feels like the community is acting differently than normal in this case.

I would LOVE nothing more than to be proven wrong here, for someone to reply with a link I missed to all the info I'm looking for. But until then I just want to know - what happened?

Thanks!

RallyJon

I think the 993 community in general shys away from electronic tinkering, at least compared to other cars. If you're the kind of guy who drives to work with a laptop on the passenger seat just in case you want to tweak A/F ratios, you won't find a lot of company here.

For a Honda or Subaru, you'd have a homebrew solution using resistors from Radio Shack, plus half a dozen vendors competing with $99 black boxes. Messing with oxygen sensor signals isn't exactly new in the car enthusiast world.

Bull

I don't know about your conspiracy theory, but I do not agree with your number one statement. I, and many others, have seen many OBD II 993s that have accumulated high mileage and never experienced this problem, some with 150k -200k miles on the clock. Several unofficial and not statistically valid "surveys/polls" have shown that around 15% of the owners of 993s have experienced the problem. Again not scientifically researched, but anecdotal evidence seems to show that 993s driven daily in heavy traffic (low rpms and high heat, etc.) developed the problem more often than 993s driven as they were intended in spirited road driving and track events.

Some cars experience the problem, some don't. Mechanics/techs often only see the ones that do have the problem...people without the issue don't stop in and tell them "no problem here".

Now back to the conspiracy............

TheOtherEric

Nobody is avoiding an electronic workaround, it's just that nobody with the needed expertise has (a) taken it on, and (b) offered to sell such a system. The "offering to sell" part is a bit problematic too, as tinkering with the emissions system is generally frowned upon by the gubment.

So the stars really need to be aligned for something like this to happen.

Marco8

What happened to the turbowerx solution? Went to the web site and they killed the product "electronic bypass of SAI test".

For the record 120K no SAI CEL, knock on wood.

Allen

Really...?...maybe I don't understand the problem. I thought that the airway/port that gets clogged, exists to allow a flow of clean air into the path of the exhaust gases leaving the cylinder. This flow occurs from the moment the engine is started until such time that the engine is "heated up"...about 1 minute or so (?). The purpose of this addition of clean air to the exhaust gases is to dilute the exiting gases that remain unburned during the period in which the engine temperature is too low to sufficiently burn the gases to the satisfaction of the "check engine" light circuit. Now...I could be WAY off here, but that is how I understand it.

So if I am correct, then the airway/port getting clogged would do nothing more than to cause the exhaust gases NOT to be diluted...thus causing a "check engine" light to turn ON....which is not a "BIG" problem, but certainly a pain in the a$$, especially if you have to pass a smog test.

Anyway, I look forward to reading responses from those who really know how SAI works. BTW, mine is a '97 with 49K miles, and I have had the SAI fault once, about 15K miles ago. It was simply reset by my mechanic and has never reappeared.

AOW162435

I'm considering an engine/tranny drop next winter and vow to completely remove all signs of that system from my OBD-1 junker.


Andreas

JM993

I just did the same thing, and while I was at it, removed the cruise control. Check out Patrick Motorsports for plugs for the SAI passages.

Davies

There's no sugarcoating this. The crap that plugs the SAI ports is a byproduct of worn valve guides. Any CEL workaround is a temporary fix. The SAI CEL is merely the canary in the valve-job coalmine.

That said, new valve guides could be considered a temporary fix also.

TheOtherEric

I see these as two different issues, since clogged passages doesn't necessarily mean your valve guides need replacing (AFAIK).

glenn993

My understanding is that it happens to all NA 993's eventually. I'll agree that it's tough / impossible to know how many people do or will have this problem. But one thing I'll argue strongly: Once you have this problem, you really have a problem. Since the car won't pass emissions test (varies by state), your car will be eventually undrivable - unless you don't mind driving with expired tabs forever, etc.

That's a big deal.

Regardless, still looking for a smoking gun - anyone been told not to do this?

Or, anyone have more information on how to do it?

Thanks all!

Mark Harris

Nice...now you just screwed yourself.

Marco8

great......

jimbo3

There are at least two causes of SAI ports getting blocked. One is worn valve guides. A second cause it a bad SAI check valve, which allows for some backflow of exhaust gasses and particulates. Could be a combination of the two as well.

Mine had an SAI CEL at 36K miles due to a bad SAI check valve. Ports were cleaned up and check valve replaced. Mileage is now 45K and no issues. Oil consumption remains constant at well over 3000 miles per quart.

If I did have a problem with plugged ports, I'd seriously consider doing a bypass. The Turbowerx chip solution would be my first choice, but it would be unlike to find one.

JM993

Agreed. My ports did not look so ggod, yet the oil consumption of my car is nil. IMHO the ports and SAI system is poorly designed and is bound to clog sooner or later.