AOS Question - 2009 Boxster Base

My Boxster is at the dealer being looked at for slight occasional smoking at startup only after sitting overnight or longer. I suspected that it had an AOS issue. The shop tells me that my generation Boxster does not have the same AOS issue and the AOS function was re-designed with this generation Boxster . Can anyone confirm that the "known" AOS issues go away with the 2009 Boxster ? I did not come across this in any of my online searches. QUESTION: How likely is an overfilled oil level to cause occasional smoking? They suspect that may be the cause of my problem. Thanks in advance.

The dealer may be referring to the redesign of the AOS. I'm putting one in this spring in a 987.2 . It's significantly different than the one I replaced in my 986 . The new one has an inlet and outlet with "O" rings. It's held in place my two torx fasteners and the supply tube is also different in design. AOS failure does not "go away" with differing iterations of our cars. Overfilling a car with oil can cause smoking exhaust and it's also bad for the seals. A puff of smoke upon start up is normal for engines oriented in a flat boxer design.

If the AOS hasn’t ever been replaced, it probably should be just because of the age. Is the smoke at startup white? Perhaps it’s just condensation? Does the car stay outside? +1 On the problems with overfilling the oil. I wish we had a dipstick so we could have a better idea of exactly where the oil level is.

Greg, Me too on the dipstick, however the reality of the " over the river and through the woods " path the 986 stick took did not make getting an accurate reading simple either. Edit: any of you members have experience with the inlet hose disconnect / reconnect for the AOS ? the YouTube I'm studying says "squeeze and twist" . I'm good with that if that's correct but I have also been bitten by the legendary German polymers breaking quite easily, I want to avoid, "squeeze and twist" now you have to replace the line too.

Thank you all for your quick replies. Awesome to have a community of enthusiasts who reply so quickly. This is my first Porsche . A convert from a long list of BMW ’s and I am grateful for a forum community like this.

Definitely curious to hear how things shake out with this, as the previous owner overfilled my 987.2 by 2+ quarts. (Yup.) Now trying to determine what's what, and if I have to go back in there and replace the AOS -- and if everything is all full of oil. Squeeze and twist - [ EDITED FOR CLARITY] Those plastic hoses and connectors broke ridiculously easy on my 2010 MINI. Same crappy and brittle plastic design and should have been rubber hoses with standard metal hose clamps. I tried applying physical pressure last week on my own hoses while in the engine bay, and backed off as I felt that any further pressure would snap the hose -- and I didn't want to deal with that (let alone didn't have a replacement hose on hand). FWIW, my 2005 987.1 ALWAYS smoked at startup, especially after sitting for a long period of time. Meanwhile, I just cleaned my MAF on my 2010 last week, and smoke filled my garage. So again -- I'm curious to see how things go in this thread. PS - Our 987.2 require driving for a bit and warming up the engine BEFORE being able to read the oil level. A HUGE PITA as opposed to both previous and later versions.

agree with all said, the redesign is as mentioned, but the failures can happen and it should be on everyone's PM list between 50-70K. Its not an overwhelming PM and the removal and replacement is pretty straight forward. The 987.2 is a bit harder , IMHO than the 987.1 . Smoke at startup, also mentioned it normal , if it stays , your idle is erratic , and or exhaust tips are excessively black then suspect the AOS. MAF cleaning can be problematic is not done correctly , if there are no related codes, leave the Mass Airflow Sensor (MAF) alone. There are cleaners available for the MAF but you can do more harm than good because of its delicate exposed parts designed to measure air flow.

Dear Foodbiker , (and Zuffenhausen) So what if it's ugly? Sometimes simple is better. I will take photos of my replacement and add commentary but the job will not be completed till likely April.

On my 2010 CS I found that if I filled the oil to the full mark (not the overfill mark, just the full mark) I'd get a bit of oil in the intake. It would pool in there and occasionally cause the puff of smoke at startup, and it would also seep out of the intake hose onto the top of the right head. AOS was good. Filling the oil one bar below full has fixed this issue.

I was just about to create a new post about an issue I'm having that sounds like it might be AOS related. 2012 Cayman S PDK , 112,000 miles For the last few years I notice a small puff of smoke occasionally on startup. Attributed this to the "design" of the engine, didn't think anything about it, oil consumption normal. Today I moved the car and noticed some spots of oil under the car near the oil filter housing location. Inspected the oil filter housing, the cooler that is in that area ( PDK ?), and both are dry. Noticed that the underside of the intake tube that runs from MAF to air box was wet with oil. Looked from the top side of the engine as well and everything else in the compartment is dry. The oil on the intake tube seems to be localized to where the tube from the airbox to MAF splits, which leads me to believe oil in the intake tract is seeping through that joint. I'm guessing the reason there is a significant amount of oil in the intake track is AOS related. Thoughts?

@Boristhespyder - Sorry; not sure I understand. What's ugly? I just hated to have to keep re-jacking up the car multiple times to keep removing oil from the previous owner...and then having to go drive to test it out each time. Just miss a proper dipstick like my old VW bug and my E30...but technology and design moves on. I personally just found it confusing that Porsche changed the oil level measurement procedure from 987.1, 987.2, and 981. BTW - I totally agree with you that "simple is indeed better!"

Food, the simple hose clamp in the photo, ugly? Yes but ubiquitous on cars in the seventies. Also quite bulletproof, seldom were the times the worm gear interface with the perforated track would fail. It will never snap in your hand and frankly, at the risk of shocking everyone if my plastic end does snap in my hand I'd consider replacing it with this if that's possible. Metal hose clamps laugh at heat cycles, not so with plastic. 95% of these are from that era and from old cars, that's what happens when dad was a WW2 vet and lived through the depression.

That's what it'll do if you get oil in the intake, yeah. What I'd suggest is disconnect the MAF and clean it and the hoses out best you can with some rags (you can't fully remove the MAF from the car easily but you can get it loose and spray it down with MAF cleaner). Then re-tighten the clamps snugly. Also check the top of the right side head, if you see oil pooled there then tighten the big sliver strap clamp on the intake manifold a bit and wipe down the underside. If you keep your oil level one bar below the full line it probably won't happen again. It's possible your AOS is bad, of course, but the 987.2 AOS doesn't seem as problematic as the earlier ones so I probably wouldn't start there.

@Boristhespyder --- Ohhhh! You meant the simple metal "jubilee" hose clamps. I'm totally not knocking those for a second. Simple is best - they're great - and they should have been left alone everywhere. I was throwing shade on the new one-piece design that is on some of the P-car plastic accordion hoses, and were also on my wife's former MINI. They're crappy plastic connectors that snap if you try to unlatch them. (I think we're on the same page here, and sorry for miscommunication.) Are you saying you'll be doing your own DIY and replacing all of those? A huge thanks to you guys for posting the above. My 987.2 actually DID throw a code per the MAF...and I just did a sensor cleaning last week. Sprayed it down inside the engine as it's nearly impossible to remove the MAF (one integrated unit) from the engine housing on a 987.2 due t a lack of clearance. The hose between the MAF and the throttle body tore in taking it off...and the hold-up on my end has been replacing it. Hoping to clear the codes with the PIWIS next week and see if the CEL comes back. Not surprised that the hose (aka, "air box" according to Porsche) tore, as I could tell that the bottom piece on the throttle body side was awfully soft -- and likely degraded by constant petroleum exposure. Reminded me of the two hoses to my filter on my 2-stroke Vespa, which clearly saw a lot of oil/gas and likely destroy the rubber.

Food, I was right with you on the plastic and it's faults, "with great power comes great restraint" Porsche polymer division regarding finger torque. I also appreciate the MAF read. I'm changing my AOS really early but it is old and to me after reading the thoughts of other members (which I truly value) it makes sense. Perhaps doing so will keep the MAF and associated plumbing cleaner too. Me and my dad were tight, using his tools and what he taught me somehow reconnects with something. Oh and when it comes to free labor, my dad would have been proud of every one of us for endeavoring and learning the idiosyncrasies of our cars. "Any car is only as good as the person wrenching on it" my dad, Anthony PS Anyone think I should retain and do surgery on the old one for a planet 9 thread besides me?

I vote "yes," @Boristhespyder - I'd eagerly look forward to reading your surgical findings. Plus I wouldn't be surprised if I have to go back in there and replace both the AOS and the MAF as my next steps...

When I'm done with the job I'll try to Dremel cut the seams we'll see how messy that might get.