pp000830

Thank you for answering the question the original poster and I asked above.
I disagree, with the characterization of my posting as being "shotgunned" its major intent was to point out the considerable consequences of removing emission components from a vehicle. Many here are quick to modify their cars in ways that they may regret in the long run, Not only is the light being on or off a minor issue, related to my experience being with a '96, and with your reply and my thanks I stand corrected resulting in a proper understanding by others. But the concept of the clogging of the injector ports and a potentially expensive consequential issue for some owners, especially the OBDCII cars, that may result is a valid discussion issue and one I have not seen discussed in these pages previously.
Isn't the purpose of these boards to develop and enhance a common understanding of how these cars work and through discussion we as a group become more knowledgeable owners?
If we all had a perfect understanding of how these cars work would there be any point in having these discussions at all?
I always appreciate comments on my postings interesting, and at times insightful and entertaining, yours as well.
Best regards,
Andy

hoggel

The SAI system is a critical part of the 993 emission control system. IMO if it is operating correctly it should be retained. Clean air is good.

For the catalytic converter to operate effectively it needs to be above about 800 degrees. On cold start the ECU adjusts the fuel trim rich which drives some unburned fuel into the exhaust. The secondary air pump comes on pumping fresh air into the hot, fuel rich, exhaust. The unburned fuel combines with the oxygen from the SAI and burns in the catalytic converter heating the cat to operating temperature. If the SAI is disabled the rich fuel mixture on cold start just goes out the tailpipe. On cold days or short trips the cat may not heat to operating temperature and significantly higher levels of unburned hydrocarbons, nitrogen oxides, and carbon monoxide.

Given most 993s are not driven daily and the cost to repair the SAI is very high the decision to repair it if it is not functioning correctly ... . Well, there is probably a more cost effective way to offset your personal environmental footprint.

71-3.0-911

Is like to know this as well. When the time comes, I'd love to remove the whole thing on my 96.

mpruden

Yes. 1996 and later cars check the function of the SAI system automatically. If that check fails, the ECU will throw codes and illuminate the CEL.

Mark in Baltimore

Andy,

This is not just a discussion board, but it's a technical discussion board. The OP started a technical discussion and expects technical replies.

This is shotgunning answers:

You posted this in response to the OP's 1995 993 SAI issues:


The OP asked a good question by questioning your statement:


Your answer is "Maybe not, I can't answer that"? If you don’t know the answer, then why make your statement in the first place? Shotgunning.




You also posted this reply in another recent thread regarding adjusting seat height:

tstafford corrected you; the female, seat belt release button portion is attached to the seat and has been attached to the 911's seat going back to at least the 1970s. Shotgunning.
https://rennlist.com/forums/993-foru...side-seat.html


Bob Rouleau has previously PM'd you and stated that moderators try to make sure that technical topics are as factual as possible and devoid of extraneous material so that people who are looking for answers have "clean and accurate" solutions.

To be fair, many of your replies are definitely correct, but you do have a history of supplying untrue information, with quite a number of your replies having been withdrawn by you once you've been corrected. As I've written to you before, it's really great that you're trying to be helpful, but you do need to ensure that your tech replies are 100% precise. Quality over quantity should be the key phrase here; many inexperienced owners are relying on all of us for valid information and may associate frequency of replies with technical prowess.

Apologies for the threadjack.

Cupcar

A personal observation. The system blows air into a longitudinal gallery drilled into the camshaft housings that leads to smaller galleries that lead to the exhaust ports. As stated here above '95 OBD 1 cars don't throw a check engine light when SAI is inoperative. Since this is the case, a '95 may go a long time without SAI service and the entire system will become plugged with exhaust residue during that time. And I mean plugged as in like rock.

When rebuilt, I found that my '95 engine had all these galleries plugged and they probably had been so for years. So, having a fully functional system in a '95 could be an expensive proposition if the system is plugged as mine was and the engine needs a tear down to the cylinder heads. If it needs a new pump added to the bill, Air Pump 993.624.103.01 is $1375 at a Sunset discount.

Potentially a lot of money for a system to operate that works for 3 minutes after start up in a car that is not a daily driver so may be started infrequently anyway.