2ndof2

BTW, the fact that #1-3 is where the fault is indicated may possibly fit into the "early stages" category. Let us all hope the "little red devil" does not rear "it's ugly head" for your or anyone else!!!

Rob Kwate

If the problem is in fact in the "early stages," then the time to clean them out is now, while the techron and carb cleaner will dissolve the carbon, as opposed to later after the carbon is "coked" and so hard that an engine tear-down is necessary to clean the passages. Joel Reiser covers this issue extensively on the PCA website. Cleaning the passages is time consuming, but not that difficult. The parts cost about $200, which sure beats a $6,000 tear-down.

Just my thoughts, Rob Kwate.

CAHRERA

I only use Chevron gas which has the Techron additive in it. But I guess it should be good to actually add a bottle of Techron after every oil change. Right? Or should I do it every few tank fillups. Luckily I haven't had any CEL errors. I do have a Smog Test coming up this year though.

Can't you get you car passed by smog if you go to a referee station? Let's say you didn't have any CEL errors or believed that you didn't have any CEL errors but couldn't get the OBDII into Ready State. I thought you could.

David in LA

Actually I think it's BEFORE every oil change.

Rob Kwate

Scott:

I think you're confusing running a bottle of Techron through the tank, which will clean the intake, injectors, and combustion chamber, with a mechanical procedure, developed by Joel Reiser and maybe others, in which the heat exchangers and the secondary air injection check valve are removed and Techron and carb cleaner are poured into the SAI passages to (hopefully) dissolve the carbon. The SAI passages open up into the exhaust port just downstream from the exhaust valve, so the Techron you put in your gas tank will never get into the SAI passages. Do a search in the 993 forum under "chewing gum" and you'll see two threads concerning the SAI passages. One of them is a DIY article I wrote up, which includes pictures. It is also posted on p-car.com. Read the article and check out the pictures, and I think you'll understand why a bottle of Techron in the tank will do absolutely nothing to clean out the SAI passages. If you still have questions, we'll keep working on this until you know everything there is to know about carbon build up.

Take care, Rob.

2ndof2

Rob,
I read the thread on cleaning the SAI ports when you posted all the details a while ago. I went back and saved a copy to go over with my mechanic. Sounds like if he can fix Volvos he can do this. Hopefully the carbon buildup is fairly minimal. So you say you estimate it taking about 4 hours? I think for 4 hours of labor and 1 or 2 hundred bucks in parts its the way to go before I get a CEL. MYnext smog test isn't due for 2 more years, but I'm not going to wait for a CEL or smog test time to get this done. Thanks for the info. I hope this works for my car.

CAHRERA

Thanks Rob, I definitely check it your write up on cleaning SAI ports.

FisterD

2ndof2, I believe that is the procedure that was done on my car. It is the same procedure that is done by Hershiemers Motorsports in Southern Cal. They use chemicals to soak and clean out the SAI passages, and also replaced the air check and air injector valves.This was the first time this mechanic had done this procedure, and he was initially pretty sceptical, but, afterwards said he got quite a bit of junk to come out with the chemicals. Hergsheimers gave him the procedure, and they have supposedly had great success with it. My car was his first try at this, and so far so good.

2ndof2

Darin,
How much did your mechanic charge to do this work? Did he say how long it took him to complete the job? Also, was you car showing any symtoms of the SAI being clogged, any CEL etc? I have a 60K service due to be done in 7500 miles which may be in about 6 months if I don't find a cheap commuter vehicle before then. I'm not driving the 928 much as I'm planning to sell soon so the 993 is my DD for now. Might do this procedure before the 60K service since I need to bring it in to have my brake booster/master cylinder replaced.

24FPS

finally had my cel pop on today (first time ever @ 35k mi.) after some spirited driving.
btw: passed my 'smog test' last month & i only fill w/ chevron & do techron before every o-change (+).

but................... i'd still put money on it, that i've got build-up. i've got an extended warranty (expires @ 50k mi.) that will cover work. i'm hoping for the best/worst case senario, as i'd like a free clean-out & some new valve guides !!!

2ndof2... i'd find out what those readings were & i'd def. let the 'po' know those re-settings should have been disclosed. seems kinda' dirty, if i understand your post correctly. i'd have surely paid less for a 993 w/ unresolved 'cel' issues... something's fishy. my ¢2.

bol w/ the fix.

btw: rennlisters might wanna check phil's old post re: the "check-valve" as i do believe you should change it out sooner than later... mine was baked-on & could not budge a few mos. ago but i opted to leave (as i had the warranty).

2ndof2

24FPS,
The PO only had the car about 3 weeks. Some have said THAT sounds "fishy" which I agree. I spoke to the mechanic who did the PPI for the PO and he said his OBDII reader did not show any fault codes or any stored. I've known that mechanic for 4+ years and have spent many evenings having beers with him and the other techs at his shop after hours. This guy even lent me his car on several occasions when I was having mods or repairs done to my 928 in his shop. Why the full diagnostic my new mechanic (who is closer to where I live now) showed 8 SAI faults is concerning, but I would have figured that if the car really had this many faults that it would NOT have passed smog before I bought the car. I have NOT had a CEL nor have I needed to clear any SAI faults. Since the PO (or guy before him) had a smog test done to change ownership and re-register the vehicle only several weeks before I purchased the car, I was not required to have the car tested again. If I am correct, a stored SAI fault would have caused the car to fail smog. It may be there's something wrong with my new mechanic's diagnostic testing equipment (he bought the software from a guy selling it illegally). Who knows if its reliable or not? I trust that the mechanic who did the PPI was not lying about anything. If he says the reader showed nothing I believe him, that is unless somebody else in his shop did it and told him there weren't any fault codes. I kind of doubt that. I've known him long enough. As far as the PO is concerned, I really didn't get the sense that the guy knew anything about any fault codes either. Again, the CEL has NOT gone on, and I hope things stay that way. I plan to look into having the ports cleaned if in fact it can be done reasonably inexpensively. Cost of a full tear down vs. cleaning the ports before they get real bad - I vote for the $400 or $500 it'll cost to try cleaning it BEFORE things get bad.

24FPS

there ya go (also, not all readers will read our 'obd II' correctly)...
but 'iiwy' i'd still have a look @ the "check-valve" for sure... it's an inexpensive part ($38 when on ebay) and according to some respected shops, will head some problems off for you big time. again, bol dropped my 993 off @ the 'stealer' today... we'll see.

SCMomentum

Bottom line....OEM valve guides are not good. You will eventually have to have them replaced.

I spoke with Tony Callas of Callas Rennsport today and he has reservations about the SAI "cleaning" procedure. He didn't say don't do it but expressed his opinion that this was only a temporary fix...maybe 10-12K miles and eventually replacing Porsche's lousy valve guides would be the best thing to make this problem go away for a much, much longer period. He said to factor in $6-8K in this type of work ($6k+ because once the motor is apart there will be more work that will probably need to be done). He felt the $5K estimates were too low and that in the end the owner will be out more than that.

2ndof2

Kinda sounds like once the valve guides have gotten bad enough to clog the SAI ports to the point that the CEL goes off, cleaning the ports may work but they'll get clogged more quickly the next time. In other words, the clean-out procedure may have to be done increasingly often to keep the ports clear. Definately sounds like a case-by-case decision on which way to go..full tear down and valve guide replacement/boring out the ports or just keep clearing the ports once a year or so going forward. Aside from harming the environment and having to top off the oil every now and again, is there any major detrimental effect of leaving the valve guides alone and just cleaning the ports? How would you tell if the guides are completely toast and what other damage could this cause if not addressed? Also, what is the amount of oil consumption per 1000 miles that is considered to be the threshold for replacing guides?

24FPS

damn..... just found out my 993 simply had an air hose come loose! lucky but not. ---was hoping for a freeby... my bad.

btw 2ndof2: my car uses very little oil... i'll maybe add a quart before a hard 'funrun' if i'm nearing an oil change. but i've never seen my gauge/stick in the 'low' area. currently @ 35k & change oil every 5k miles.

cheers.