New AOS same problem
 

I installed my new porsche direct AOS unit and still have the sucking sound,..if I plug intake and AOS tube connections, No more sucking sound ,..Can you vacuum test the AOS.. plus all codes still the same aswell..Bummer,..So I guess fuel presure test and then smoke that babie I guess.? right Thanks Frank

Codes: P0300,..,04,05,06 and a P1238 secondary fuel system ??

You can test the AOS by replacing the oil fill cap with a test cap hooked up to a digital manometer. Fully warmed up, you should see no more than 5 inches of water vacuum signal.

Source/link? This is news to me and I would love to check it out.

Been around for years...………….

https://www.youtube.com/watch?v=t95lNYp2plc

Ahh ok...But the Idle does lower when I pull the oil filler cap,..Thanks !

So does a marginally bad AOS. The manometer gives you a simple way to test the vacuum signal and even catches units just starting going south. We check every car going through the shop, regardless of why it is here, 5.0 or less and you are golden; over 5 and you need an AOS. Testing regime has cut back dramatically on catastrophic AOS failures.

Any part you buy from a Porsche dealer has a 2 year warranty.

That's good news Byprodriver,..JFP,..whats a decent (cheapie) Manometer to get,and is it a common item to get around town,? Thanks once again guys..Frank

I bought this one, and it's served me well.

JFP turned me onto this method of testing the AOS as well. I LOVE that he just does it on every car as a natural course of operations. Hard to find that sort of service these days. (Wish he were near me)
I've started checking mine as I'm preparing for every Track Event.

Thanks for the info, y'all. This seems like a must-have for my shop.

Thanks,for that tip Maytag,..its on order, so as soon as it gets here Ill do that test,.!

I get the Manometer that Maytag suggested,..But Iam Not sure if I hooked it up correctly,..I set it to INH2O used the RHand prong and it shows ( - 1.47 ) cold ,.I know its suppose to be at operating Temp,.but Iam checking to see if I even hooked it up correctly,.....oil cap drilled with a brass fitting that I epoxied into place,.and then attached a 3/16 tube that was supplied..?? Thanks Frank

I've never measured cold. I can't help ya with that.

Get it warmed-up and see what reading you get. I'm typically around 3.7, fully warmed.

It really shouldn't matter which side of the manometer you hook to; one should read positive, one should read negative. You'll probably want to put a hose on the other nipple as well, though, and route it somewhere where it's protected from any wind or venting. It'll be very sensitive.

I assume you watched the video that JFP linked you to earlier?
Read this thread, for more help:
https://rennlist.com/forums/996-forum/992560-tested-my-aos-today-what-does-this-mean-2.html

Yes Maytag I sure did check out the link JFP referenced,.and now the Rennlist link you showed,..Thank You,.!! Frank

Now,I went to the left prong,warm at 180 Deg,and meter read's 3.18 to 3.30 fluctuating. Thanks

Frank, that's not too far from what I read on mine. (I'm usually closer to 3.7)
I've taken that to mean the AOS is currently healthy. But I've only ever seen the one. JFP will have much more data behind his advice. Let's wait and see what he says.

Sent from my SM-G970U using Tapatalk

it did increase to 3.75-3.80,..but I pulled the intake to AOS hose like JFP said to check vacuum and I have oil in the top of that AOS and the connecting tube,..enough to cover the tip of my little finger twice over,..and can tap oil out of the new tube. ! So another one on the way..I sure hope this is the issue,..and I will also drain some oil to be safe now,..like Newart has suggested in another thread.! :confused:

Who's are you buying?

Direct from Porsche,

as was the last one,..I didn't want to chance a bad unit,.Lol..:)

well same problems persist,..so I ordered a new MAF sensor...installed the new AOS,. Runs a bit better but still hisses so I will now pull the alternator so I can look for vacuum leaks,.but if I disconnect battery don't I loose ALL the stored info..like over rev's Etc..I have never been able to research the engine that way and I sure would hate to lose that data,.?? Thanks frank

well still no cure on my 2.7,...I did pull Passenger side intake runner and Alt. to get to the Vacuum parts, replaced the canister, all new line,and fittings also the one way valve to resonance flap, had injector's tested they are fine, new oil tube to engine replaced,new MAF sensor, and of course intake seals,..and it still has a vacuum leak some where you can hear it sucking air, So I disconnected the AOS to intake tube and plugged it.So at idle there's no more hissing. But when I rev it up a bit it starts sucking in air from some where, could the little bellows on the bottom of the AOS cause such a loud sucking sound if its not 100% sealed .My smoke test didn't reveal any major leaks I could see,..But I didn't look underneath the car at that time either.?? Going to the shop soon if I don't find the source of that sucking sound..Thanks Frank

When you replaced your AOS (however many times)... did you replace the bellows at the bottom of the AOS? What kind of clamp did you use?

Hey Starter,..yes ( replaced twice) and I used a new bellows each time but with a worm clamp ,.I will double check that clamp tho..Thanks

So far the shop blames it on those little furry bastards (field mice or pack rats)