ms9811

Well, I've tried a few rounds of resetting the light and then using Techron cleaner in a few tanks and while it keeps the dreaded CEL/SAI light off for a while it keeps coming back after a few hundred miles, no matter how I drive it. All of which leads to the following (related) questions:

(1) Is there any harm (other than to my eyes) in driving the car with the Check Engine light (caused by the SAI) on?

(2) Does the Check Engine/SAI clogging make the engine go into any kind of special mode that would either hurt performance or do long term harm to the engine?

(3) Will postponing some kind of clean out make the job harder down the road?

(4) It's probably posted elsewhere, but what are the least invasive methods for cleaning out or otherwise taking care of the SAI ports to buy more time before doing a bigger repair?

I ask only because the car has only 70K miles and I just did the valve cover seals and spark plugs and the car is dry as a bone, burns no oil, and the old plugs looked like they had worn perfectly (no evidence of running rich or lean) so I HATE to mess with something unless I have to.

Thanks in advance.

Ed Hughes

How do you know what the CEL is for? Did you check the code? It won't harm to run prior to a resolution.

goofballdeluxe

No.

Carbon deposits build up in the ports. They can be cleared out by a knowledgeable mechanic, or you can search here for some DIY fixes that work too.

If you don't need to smog the car, you're fine

ms9811

I pull the codes each time the light comes on. It's the SAI.

TJ993

In reply to your Heading - YES.

You need the correct reader to telll you what codes you have.
Step 2 is Delete Codes
3) dO BMW DRIVE cYCLE/S TO RESET MONITORS
4) WAIT FOR ERROR CODE TO RE-APPEAR
THEN U KNOW U HAve a problem

To Answer your questions:
1) Yes
2) Yes - Car starts Pinging - Long Term _ My Opinion - Not Good
3) Yes- somewhat - Concern is Long Term on the motor.
4) Determine the Code First. Be certain Clear Code Reset Code/ drive Cycle/Set Monitors / Drive it and wait for Codes to RE-Appera - Confirms she is Sick.

Go to a Mechanic and get Codes Read.
Then u can do the DIY if its the SAi - Costs $2-$500 if u have the Tools
Go to a Mechanic - Spend $1000 - $1500 to repair

Alternative is have a Read of this Post writtem by me:
. “Relative Newby – Seeking Varioram SAI - Vacuum Leek Assistance”
This is what I have been told by a skilled mechanic: The longer the codes sit in the car it will do damage to Catalytic Converter – BIG $$$$$$$$$$
The SAI CEL will Retard engine timing to protect the engine – the DME / Engine Computer Thinks there is a problem.
The cut back of Power and pinging is extremely annoying!
What happens is the DME Retards ignition timing, the Exhaust rings out the "Ping" sound and soon after the CEL Re-appears.
The Ping is like Bad Gasoline - Ping Ping
Find out what the Codes are by having someone with the Proper Equipment to Read the Codes…a Bosch hammer or PIWIS Tester – Both Porsche Tools. Start Here and Update your Post with results –What Codes is she generating?
Tom

goofballdeluxe

^^^^ I've never ever heard that having a CEL light due only to SAI ports being clogged will in any way harm the engine.

I've never heard the SAI CEL will cause the engine to retard engine timing or that it will damage the catalytic converter either.

Maybe someone with deep knowledge can clarify all this?

Thanks

race911

I think the comment is more about what weak valve guides cause--carbon buildup and oiling the cat. The OP claims his car doesn't burn oil excessively, so I'd say in his case it's of less risk.

(Got a look at a set of sub-50K heads a few weeks ago. Wow. As I always say, if you guys could DIY factory guides out like a set of brake rotors the replacement rate would be 100%.)

nine9six

In reply to your Heading - No

Proof of that is the 95 993 which has the same SAI ports, and the OBD I system in the 95 993 does not monitor the SAI system. These ports can clog till hell freezes over, with no detrimental effect to the the performance of the engine.

The SAI system acts as a bellows in a furnace and blows air, which contains oxygen and speeds the heating of the cat...If the cat heats slower with just hot exhaust, it does not harm the engine. Overall it may lead to a clogged, somewhat prematurely non-functioning cat, but I have yet to see any data on the 95 993 going through cat at any higher rate than the 96 - 98 993's.

Only the OBD II system in the 96 - 98 993's monitor the SAI function and will throw a CEL, if the ports clog.

NO

NO

Yes, more than likely, as more carbon deposits harden with repeated heat cycles and additional deposits build up.

Indeed there is...There is an ADMIN post at the top of the 993 forum: Recap of the SAI circuit, which outlines the SAI system and methods for clearing the ports! Enjoy the reading...
https://rennlist.com/forums/993-foru...i-circuit.html

TJ993

Oh my, do you think a Mechanic would lie?

Where did the Pinging come from? vacuum Leek ?
There are many sources for potential vacuum Leeks.
Would the Leek create a different code?

In my case, the TT Pipe compressed in the colder weather here.
I had a ripped Vacuum unit
I had a clogged Resonance Flappe
I had a few clogged ports

The Pinging stopped when the vacuum Leeks were rectified.

The CEL as nine9six knows was Cleared after drilling out the Ports.
Needed a Compressor as I left it too Long!

My car is burning Less Oil now. How??
Thanks again for your assistance!
Thanks Rennlist !!
No CEL after 4,000 Miles to date and Damm It is Cold here! 30 degrees F !

My motor is pullin nice with 100,000 on the nu valve and exhaust guides.
I would like to hear more feedback because as stated earlier these are and were my experiences.
Time for a drive!

goofballdeluxe

I don't think your mechanic is a liar, but, given how the OP is talking about a CEL only due to clogged SAI ports and nothing else, and not about vacuum leaks, any other "leeks", bad resonance flaps, worn valve guides or any other unrelated issue, I think it's highly possible you're misunderstanding what he's saying. You also may not know that clogged SAI ports and worn valve guides can be completely unrelated issues.

Given that race911 aka Ken, IS a long time Porsche mechanic and air-cooled engine expert, I think I'd listen to what he says, rather than what any one else heard second hand from someone else

hoggel

A steady CEL means a failure has been detected that impacts operation of the emission control system. A flashing CEL means a failure has been detected that could cause damage to the engine or emission control system.

As nine9six said.
The ECU drives the fuel mixture rich during SAI operation. The combination of unburned fuel coming through the cylinders and oxygen from the SAI burns in the catalytic converter quickly heating it up to the temperature where the catalytic reaction can occur and sustain itself. If the SAI system is not working properly the temperature in the converter may not reach the reaction temperature, depending on trip length and the ambient temperature. If the catalytic converter is not operating effectively in a car it will be emitting approximately 10x the harmful particulate of the same care with a functioning converter.

I think we should do everything within reason to keep our emission system working on our cars. If there is a good reason why your SAI system cannot be repaired at least you should drive everywhere at maximum RPM to heat the converter and shorten the trip.

pp000830

My understanding is that the air pump injects a little air into the exhaust for a few seconds at startup only and then shuts down. Given this do not know how it can have any effect at all on the engines health. The light may be on for a number of reasons including several common and inexpensive items such as the injector one way valve getting dirty and stuck.

Don't assume the worst have it looked at.
Andy :-)

993inNC

^^^^^^^^^^^^^ You are correct. The SAI pump and system only works for the first 90 seconds within 3 seconds of the car starting. The only thing the CEL is relaying to you is that there is a difference between the pre and post O2 sensors readings. When the SAI system isn't working, the post O2's aren't heating up quick enough to send a different reading than the pre cat O2's.

You can clear your codes but these cars are a bitch to reset. I have had the issue for 10 years on my car and trick the computer every year (in the middle of trying right now) when my inspection (OBD check only) occurs. If you want to check what I'm telling you (and your car has no other issues). Clear your codes and then DO NOT allow the car to idle or even close within the first minute and a half from start up.........your light will stay off.

All 911 motors from around the late 80's on (IIRC) have this issue but it wasn't until OBDII came along that the issue could be monitored via the O2 sensors. There is no harm to the motor, if there was, my 5 years (plus the previous owner's) of track time with my car would have grenaded the motor long ago!

richardew

I've had at least one port clogged for over 200,000 miles. I first threw the SAI CEL around 89,000 miles. I had them flushed just over 100,000 miles and one remained clogged. Then again, I might just be lucky.

goldcountryboy

The porsche mechanic I took my car to charged me $500 to do a check valve replacement and SAI port cleaning.