https://www.yourmechanic.com/article...by-jay-safford


Good article here. I did the SAI last year- it was bad for sure. The valves however and the engine are super clean. I don't burn any oil and the ceramic on all of the valve guides are still white with no carbon build-up. I still throw a 0410 code now and then. I am pretty certain it's one of the o2 sensors- they are $ 100 bucks each and there are 4 on my car so I am going slow with this.

 

I was able to tell exactly which O2 sensor was bad according to the code, so no need for guessing.

 

If they got a good amount of penetrating oil down the check valve hole it may have served to reduce the flow or clog the air injector passageways.

 

there is a little vacuum hose that attaches to the sai assembly that when comes loose will throw a code. it may not have been connected securely when they replaced the check valve. worth a look.

 

not to mention its not even for the op's car it's from someone elses. look at the date its from last year and it also shows how the other party paid for it.

 

^^ OP said he "put the estimate in the drawer to deal with later"... a year goes by and now he needs it smogged...

 

 

Where is this vacuum hose on the SAI assemply??

 

 

You can investigate check valves and o2 sensors all you want, and maybe it's worth doing just to cross them off the list, but the above is hard evidence of the real problem. Worn valve guides.

 

^^ I thought 1qt/1000-1500 miles is considered acceptable. I've read 1qt/600 miles is about the max loss acceptable...??

 

A healthy 993 motor burns zero quarts. The factory lowered the acceptable standard after a significant percentage of 993's were burning oil when brand new. Shops were tearing down heads from cars with a few thousand miles on them and finding guides out of spec from new.

OP's engine has been burning oil its whole life, so no surprise SAI ports are clogged at 62K.

993 valve guides were not Porsche's finest hour. There should have been a recall, but the problem was so significant it probably would have bankrupted the company. So they moved the goalposts.

 

It's been 5 years now with zero problems, so I'm a little foggy on this.

Alright looks like I found one source:

http://www.systemsc.com/codes.htm

Look for codes: 0130, 0140, 0150, 0160

There are other pages out there with this information.

I think it was throwing a 0150, bought the appropriate Bosch O2 sensor, installed it, and BANG, problem gone! I was really happy and surprised the codes worked so well.

 

While I am sure there are instances of your posted claim; I have yet to see any conclusive documented data to support such an egregious global claim.

If there were, the people who buy Porsche 911's new, certainly have the wherewithal to solicit a law firm capable of initiating a class action suit against such a company with deep pockets.

It seems more likely, that shops that make their living on selling top-end rebuild's are more than happy to propagate such a global claim.

I am not saying the Porsche valve guide material selection could not have been more robust,; nor am I implying that there were zero, out of spec valve/valve guides as shipped from the factory.

I am simply saying, that all things being equal, one scenario would seem too far outweigh the likelihood of the other.

 

On recommendation here I talked to one of the principals at RMG in Sunnyvale about SAI issue and costs. Very nice guy there spent a fair amount on time on the phone and answered a lot of questions. A couple of things stood out:

1) He was pretty quick to say that if I am getting the cods 0410 and 1411) it is likely clogged SAI ports and not something else (O2 sensor, vacuum leak, etc). He did not seem to think that a shop could mess up putting in the check valve
2) He said that flushing and routing out with wire really don't work, no way for fluid or wire to get all the way through the blocked passages.
3) He basically said do the rebuild
4) I share the outline of the quote I got and he said that sounded about right for Top End and a clutch, no recreation to the clutch at this low mileage.

Really appreciated his time and direct answers (much better than some I have to but disappointed he did not have a magic solution for me. I was curious about comments here that costs were high and after hearing from RMG I thought i would at least check part prices. The attached compares prices I was quoted against Pelican Parts (easier to search quickly, appreciate recomendation for other vendors to check). With a few expectations prices seem in line so not sure what to make of that. Appreciate the observation that the flywheel may be fine and agree I am not sure how they know that needs to be replaced. This made me curious about a couple of things:
1) A better place to check prices
2) Cost and complexity of upgrading to the single mass/RS style flywheel (does this require re-gearing and ECU re-program on a 97?)

I think I will get someone to help me check that the Check Valve is in correctly and that O2 sensors are functioning, any thought on other diagnostic stpes before taking a plunge on Top End? (Also i will try drive cycles again but at some point I need to fix this)

Thanks