98993c2s

Either a physical port bypass (there was a thread about that recently) or a device to fool the computer...

smddanny

I understand the SAI problem but was surprised to see the DIY a few days ago detail how the port ran thru the cam carrier and head to outlet behind the exhaust port.

I seem to remember my 930 had air injection and a pump that routed air to the exhaust manifold. Seems like life was easier then, there were no internal passages. I actually can't see what is wrong with that set up either.

From what I have seen it is a common practice for the auto manufacturers and ecu producers to engage the air pump when the motor is cold between x and y temps and then look to the oxygen sensors for a change in the a/f ratio. Realizing that the factory has many well qualified engineers to run solutions and prove them and that is why the cars work well from the factory.. they are not beyond reproach (remember how many versions there are of the cooling blower fan!) and why not install a couple or air ports upstream of the cats, let the oxygen go in and tickle the lambdas and forget about the ports in the head that look like misery to clean out. If I ever have this issue with my 993 T, I would like to weld on ports near the 3-1 exhaust junction and insert the air, it looks like a lot less work and can anyone tell me for a fact that this scheme will not work.

Perhaps the combined wisdom of the rennlist can produce such a "kit" with a pair of capillaries and ports etc. Seems like life could be simpler .. no???

Danny Shapiro
993 TT '96 with 35K miles pulls and runs like a freight train on rails and loving my new hds and eibach..even though the dealer soaked me for an alignment... now I remember why I haven't bought services there for 25 years...

Traffic53

my car uses quite a bit of oil, actually. i estimate going through 1 quart every 750 miles. however, i believe porsche considers this acceptable. it is on the low end, for sure. any LESS than that is definately no good.

trojanman

Hey Mike...

Sorry to hear of your problems. As painful as it likely sounds, with your stated oil consumption it seems like your shop only tried to address the symptom rather than dealing with the cause (worn guides). I've heard horror stories about clogged ports and the inability to get them unplugged, and ultimately the only sure-fire solution is ream them while the engine is apart.

Maybe your shop would credit you all of their labor for the flush and let you put it towards a top end rebuild? Sounds like an inevitability at some point in the near future anyway.

As others have stated, I went through the "rage phase" with my car but came out the other end (the new top end!) really loving her... you can't know the peace of mind that comes from biting the bullet and getting it done until you experience it.

Probably not the greatest solution in your mind at this point, but just my $.02.

Good luck.

vjd3

I may or may not do the top end on my new 97 ... and if I do, I will probably reroute the air to the exhaust. I'll make sure and have some photos of it to post.

JasonAndreas

The problem with a company creating a product or your mechanic installing a workaround is that the EPA enforcement division will send them a letter that says, "Section 203(a)(3)(A) of the Clean Air Act states, that for any person to remove or render inoperative any device or element of design installed on or in a motor vehicle or motor vehicle engine in compliance with regulations under this title prior to its sale and delivery to the ultimate purchaser, or for any person knowingly to remove or render inoperative any such device or element of design after such sale and delivery to the ultimate purchaser is prohibited." And if you don't comply they will close your business down.

autobonrun

I agree 100%.

By the way, this problem is not limited to Porsche. BMW has the same issue with its M5.

However, my understanding is that, at least for Porsche, the O2 sensor detects the drop in oxygen level when the air is not injected through the ports into the exhaust stream, so why not just add a bypass just upstream of the sensor and divert some additional air there. I don't have the problem with my 96 (knock on wood) but that is the exact path I will pursue before I even think about opening the engine to unplug some useless holes.

vjd3

I read through the Massachusetts emissions laws; it specifically states that "temporary repairs" to the system to improve its performance are okay as long as they are not messing with the OBD2 computer system or sensors. I would interpret that as saying it's okay to "re-engineer" the system as long as it's doing what it's supposed to do ... i.e., getting more oxygen to the cats to heat them quicker, which is what my understanding of the SAI system is. I would think that would not be illegal; putting a circuit board to fool the OBD2 system about the condition of the oxygen sensor would be.

dbf73

hence the ever-popular "for use in off road vehicles only:

autobonrun

Good research. I would agree with you that changing the circuit board would fall into the category of a modification. However, a bypass, strictly speaking doesn't touch either the sensor or the circuit board. I would also define the bypass as temporary. It's just there until I open the engine at 200k miles for a real repair; oh say in 20 years. Besides, I seriously doubt a 1/4" or 1/2" tube would be noticable if done neatly and professionally.

Slow Guy

Actually, I think the "official" figure is 1L per 1000 km so you're not too far above their limit.

Converts to apx. 1qt per 625 mi.

Leland Pate

...or you could just save yourself a lot of hassle and buy a '95.

I kid you not, these CEL threads have kept me from looking at a widebody.

DC from Cape Cod

I could strap a Flux Capacitor to my engine and it would pass a visual check here on Cape Cod. I have no idea what kind of people you have inspecting your cars where you live but around here they all hate "The Man".

pedsurg

Interesting to hear about the lack of problems with the Euro cars. Adrian recently sent out a lengthy missive on the e-mail list on this topic and one thing he mentioned was the difference between US il and Euro oil.
Adrian; would you care to elaborate??

Jack

98993c2s

There are plenty of companies that produce such products and I haven't heard of any of them being shut down. 02 simulators, cat bypasses, etc.

And the way this is worded, I don't see anything that prevents a company from producing such a product; technically, the wording only applies to 'a person' who does the work on the car.