Aos failure & more
I replaced my AOS 15K miles ago. Now at startup I get a burst of white smoke, while at idle I have some smoke.
1. How long should an AOS last? 2. Am I experiencing AOS failure? 3. Would the P410 CEL code be a contributing factor to the white smoke and not AOS failure? Of course this is happening just before the 20th anniversary celebration of the Boxster at the Omni Resort in Amelia Island Next weekend. But wait, there is more, looks like my CPS is also on the way out. Getting harder and harder to start. Tach does not move during start up (how much should it move?) |
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Also, if you pull the oil filler cap off when the engine is running, do you notice any change? I occasionally get some smoke on startup, but it goes away within a moment or two (it also sits for a week at a time). |
As Deserion mentioned, pull oil cap while idling. If it is difficult due to suction, that is an indication of a problem. If it pulls off with small suction and engine idle gets a bit rough, but with it on it smooths out, that appears to be normal.
Life span is all over on these things. I replaced as a maintenance item at 87k miles with no indication it was bad. Does the smoke clear after the engine warms a bit? I need to go out and see about the tach needle while my car still starts to know the base line. I have only had the crank no start for a bad fuel pump relay Good luck and keep us in the loop |
I typically have gotten 40-50k miles from an AOS (sample size: 2). This is one of those places (unlike brakes for example) where I pay the premium and use factory parts. do you know what brand of AOS was installed? If it was installed by a Porsche dealer then it is almost certainly a Porsche part. If it was installed by an Indie or yourself that's not a given. When I take my car to my indie that's a discussion we always have before any work is done: the origen of replacement parts.
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2. Smoke at start up can be one indication that the AOS might be starting to go south, but it is impossible to know conclusively. Also, impossible to know when the final failure will occur - could be days or months or years. 3. Not likely but maybe. P0410 is a secondary air injection failure and the SAI only operates at start up so it could be contributing but the SAI addresses emission levels not smoke so that is why I say not likely. Here is a good link for the P0410 code: https://www.renntech.org/forums/topic/39927-p0410-and-p1411-running-out-of-ideas/ |
My boxster would smoke upon start up. I've found if you let your boxster idle for a moment or two before you shut it off it will not smoke when started. Worked for me, no more smoke.
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The definitive diagnostic tool is a Pyle digital manometer.Thanks Ahsai.
https://www.pyleaudio.com/sku/PDMM01/Digital-Manometer-with-11-Units-of-Measure Anyone tried the 1/2 price knock-offs on Fleabay ? or https://www.amazon.com/Perfect-Prime-Professional-Manometer-Differential-13-79kPa/dp/B00N3PPZZY/ref=sr_1_3?ie=UTF8&qid=1488476338&sr=8-3&keywords=digital+manometer |
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We have one, works fine, as does the Prime Professional unit, which we also have. |
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I've got this one:
https://www.amazon.com/gp/product/B00N3PPZZY/ref=oh_aui_search_detailpage?ie=UTF8&psc=1 Supposed to be the same as the Pyle and others. I've got an extra oil cap so I just need to get it together and I'll make a DIY and I can send it around for folks to use, although the shipping to/from would come to a significant % of the cost of the whole unit itself... |
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That is the unit I linked on Amazon.Gets good reviews factory responses there.The Fleabay ones are cheaper and are cosmetically different. That is a good idea you kindly offered - epoxy a brass nipple on the spare/test oil cap ? Something like this +a cap? Brass 1/8" Hose Barb x 1/8" Male NPT Fitting - AMFLO# 399. Or a 1/4"NPT x1/8"NPT brass bushing with a removeable 1/8" npt hose barb and a 1/8" plug to fill the hole when you are done testing?Source from HomeDepot or similar. Much better than an uncertain diagnosis of AOS beginning to fail. |
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http://i1140.photobucket.com/albums/...psh8cslbxd.jpg |
I've not yet had opportunity to put it to actual use in a real project yet, but I picked up an inexpensive EBay model.
http://986forum.com/forums/uploads02...1488512771.jpg I have been able to verify that it works, but as far as I can tell, it doesn't seem to have a "re-zero" feature, like the alternate low-price model options posted above may have. (It does have a "compare" feature which basically accomplishes the same thing, but it needs to be manually activated to re-zero after powering up each time. It's not off from zero a big amount, a small fraction of an inch of water. It's just sort of a minor annoyance that it doesn't read exactly "0.00". :) ) I will say I very much like the compact size, but perhaps they are all similarly sized. (For reference, its smaller than my Fluke digital multimeter.) I believe it will work great for doing basic diagnostic work. First project I'll probably use it on it is tankless water heater supply gas pressure diagnostics. But I can already tell it's much more compact, convenient, so much more precise, (and hopefully more accurate) than my home-made "water U-tube" manometer, which I made years ago and got some good use out of on a home-made airflow tester, which I used very effectively for custom racing intake manifold development. |
This is the point in the discussion where I plead ignorance. What will this tool do for me? Will it rule out AOS failure?
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Digital manometers are used to measure the engine case vacuum levels, which should be 5 inches of water or less if the AOS is working properly. We have had cars come in with complaints of running issues and/or smoke, and found 8-10 inches of vacuum, indicating a failed AOS.
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I recently had my aos replaced on porsche Dealer. I had these symptoms:
1) White smoke on startup (cold and warm) 2) When idle, the engine was reving by itself 3) Engine light went on ( but porsche said it was just because of the smoke ) As others mentioned, maybe an aftermarket Aos did fail ? |
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