2000m2

Apologies if this has been asked before, but I find the search function on forums to be pretty cumbersome...

I am looking at a '96 993 that has the CEL SAI issue. It is in a dealers inventory and they are in the process of fixing it. My question is what should I look for when I see the car to make sure the repairs were done correctly? Visually, there is probably not much I can see, but maybe paperwork detailing the work that was done?

Trying to get myself in to my first Porsche and want to make sure I know what I am buying.

Thank you!

goofballdeluxe

If they fix it correctly, the CEL will not be on any longer. If they don't fix it correctly, the light will come back on sooner rather than later. All it is is carbon deposits clogging the SAI ports. My mechanic cleared mine with some caustic chemicals, a drill and a bass guitar string.

pp000830's explantion below covers it in better detail.

Good luck

pp000830

[/QUOTE]Can be lots of causes:
Some say worn valve guides allow oil to slip by and burn clogging ports, implying the problem will come back.
The CEL light can also come on due to the air pump not working. This can be due to a known wire insulation problem leading to the pump a seemingly simple fix.
Another cause of the CEL is the check valve that passes air from the pump to the engine is clogged. An inexpensive part that will be replaced when the dealer does the rotor rooter cleaning.
The dealer will clear the CEL. If it returns any time soon they did not fix the immediate problem.
If your problem is related to valve guide wear the problem will likly pop up in sometime in the future.
The last cause under discussion is inadvertently overfilling the oil resulting in what appears like oil consumption but is oil overflowing into the intake possibly clogging the passages on the exhaust outlet. The key here is to not overfill the oil and measure its fill with the engine running at idle and hot on level ground. I do not fill the oil to the point where it pins the gauge as a fluctuating gauge give me additional feedback as to if the oil is warm and if any incremental oil usage is present. When refilling the oil after changing the oil filters add 8 or 9 quarts of oil and get the engine hot then add oil until you see it at the very bottom of the dipstick then add a cup at a time until it is in the center of the fill mark on the dip stick. Once there look at the gauge in the cabin if it is at or above mid gauge you are done. If you put over 10 quarts in you probably overfilled it. Changing the oil involves draining the oil tank and the crankcase and replacing both filters. Do not detach the hard oil line as outlined in some literature it is unnecessary. The small oil filter can be removed through the passenger side rear wheel well once the rubber flex duct for the cabin heat is detached. The filter can be slipped through the suspension parts and dropped out the bottom. This will be messy, I keep a couple cans of CRC electric motor cleaner on hand to wash off the mess.

Hope this rambling reply helped.

u7t2p7

Not true as it is easy to simply reset the codes and the CEL will go off a brief period of time. If it was me I'd want to talk with the shop that "fixed" the issue. Remember, the clogged ports are the effect; the cause is typically worn valve guides and excessive oil consumption with higher mileage cars.

Kika

I am assuming that the car is throwing a P1411 and/or P0410 clogged SAI port CEL.

this means that the secondary o2 sensor is not receiving the amount of O2 that it "wants" as defined by the ECU OBDII system. There are a number of reasons that this can occur.

eventually, the valve guide wear issue WILL cause this, and given time and no having a top end, the ports will get clogged and WILL cause one or both of the 2 codes listed above.

The band aid fix is to try and clean out the ports, however that addresses the effect, not the cause. The cause is (popular belief) that the guides are worn, and oil is blowing by the exhaust valve, clogging the port. Having JUST got my car back from a top end job, and seeing first hand the complexity of the ports, I believe that it is pretty much impossible to completely clean the ports with the so called roto-rooter of bass guitar string method. which is not to say it can't buy you some time.

I would ask the dealer how they addressed the problem, and how they fixed it. Ask open ended questions, not, did you replace the valve guides, and did you use OEM guides or PB aftermarket ones. Let them provide the information, not a means to tell you what you want to hear.

in addition to paperwork, including a warranty, it would be nice if they provided photographs of the rebuild. I doubt a dealer would go through that effort, but the shop that did my top end gave me a thumb drive with photos of the complete rebuild. I didn't really need proof, as I was at the shop twice a week monitoring progress as it was made.

If a dealer is doing the work, they SHOULD fix by doing the valve guide replacement. this by no means guarantees a quality job however, as there are items that need meticulous alignment (cam gears to crank shaft for one) that can cause other issues. ditto with setting the timing, just because they did the right job doesn't mean they did the job right.

nine9six

There are no true statements if one inaccurately paraphrases a ^^^ comment. However, the statement in its entirety below, is indeed true; albeit abbreviated in its content.

There are various contributing causes to clogged SAI ports, with no substantiating data, positively identifying a primary root cause.

Some of the contributing causes have been noted above, and do indeed include overfilling the engine oil, non-functioning SAI stop check valve, along with worn valve guides...

Excessive oil consumption is a result of poor sealing rings, valves, and worn valve guides. Not a contributing cause, in addition to worn valve guides.

Lots of background info contained in the Admin posting at the top of the 993 forum; recap of the SAI circuit...

https://rennlist.com/forums/993-foru...i-circuit.html

HTH

TJ993

GET A GUARANTEE - IN WRITING

As part of your PPI, Prior to Purchase I would hire a Mechanic to Measure Valve Guide Wear by Measuring Side Play in the valve Spring Assembly using your own Independant 993 Specialist <> an experienced Pro

E30M3

Has anyone ever successfully unclogged the SAI ports by using Seafoam?

boman993

No way...Perhaps if they're not fully clogged. But jetting through any liquid or foam through the passages when they're 100% blocked would be impossible. There are almost 90degree kinks in there, so you need to get in with something abrasive.

As far as "checking" the shop's work....The worst part is, is that there are varying degrees at which you can do the clear out. Even if they did the procedure with the heat exchangers off, and the dreaded Check Valve off, they could still half *** this. I bet if you got through the carbon buildup just enough to have airflow, the CEL would go away. However, the carbon would build up again pretty quickly bringing you back to square one. I spent a few days with a drill and bicycle brake cable drilling out the stuff when I did my service. The last few techron flushes yielded crystal clear, so I figured it was good to go. Still no CEL after 2 years and 7K miles. Going to change the Check Valve soon again though...

E30M3

I figured as much..Perhaps it would not hurt for one to run seafoam in their engine once or twice a year (depending on how much mileage they put annually) along with walnut blasting as preventative maintenance?

boman993

Not sure about running Seafoam in the car. Never heard people do this, so I'm not sure. Walnut blasting won't do much...the ports exit into the exhaust so there is nothing to blast there.... The only way to clear out the SAI passages with the engine together is with a flexiable abrassive wire chucked to a drill through the openings in the exhaust chambers.

E30M3

I guess there is no way around it then...

2000m2

Great suggestions and thoughts all around, thank you very much! I feel better about going to look at this car now with an idea of what to look for/ask about.

Kika

and even then, there are many twists, turns and branches that would present challenges to completely cleaning them with a flexible wire.

solvents poured in from the top are another method, but if one passage is blocked, the solvent will seek the path of least resistance and flow through an alternate branch, if it is less restrictive.

roto-rootering and solvents CAN help, but unless the cause of the clogging is fixed, the ports will simply get clogged up again.

boman993

This is true. A top end is looming in my future. I'm just waiting for the oil consumption to get to a point where it matters. Right now, it's consuming oil, but very little. Also, in my service records there was never a record of SAI work being done during the life of the car. Once I drilled mine out which was the first time in 16 years, there has been no return of the SAI CEL..is it going to clog again? Probably. But my plan is to be on-top of it ~ change the Check Valve every 15K miles. And if the light comes on before my top-end plan, drill out the ports again.