AOS Clarification

[shihman]

2000MY, Boxster S, 100800miles.

hi guys, last friday morning when i go start my car, a big puff of smoke came out. i thought i blew my engine. then the smoke slowly burned away. so i did a search here and all the symptoms point to a failed AOS. Along with the big white puff of smoke, i also felt lose of power lately and a fluctuating engine speed when idling.

after some search i found the part number for the AOS (996-107-023-04) but i need someone to confirm with me that i will need a Y-tube NOT a J-tube correct? i will make the purchase as sson as someone can help me confirming this. is there anything that i'll need?

so far i had my car for about 7 years, i have only changed the O2 sensors, the MAF and the ignition key switch myself. i don't even consider myself qualify as a weekend warrior (DIYer). but since i was also laid off last week, money is a little tight. is this something i can do myself? can someone send me the post if someone has already posted before? if not, does anyone knows what is the approx. labor cost at a shop?

thank you all in advance for helping me.

[HairyPotter]

2000MY, Boxster S, 100800miles.

hi guys, last friday morning when i go start my car, a big puff of smoke came out. i thought i blew my engine. then the smoke slowly burned away. so i did a search here and all the symptoms point to a failed AOS. Along with the big white puff of smoke, i also felt lose of power lately and a fluctuating engine speed when idling.

after some search i found the part number for the AOS (996-107-023-04) but i need someone to confirm with me that i will need a Y-tube NOT a J-tube correct? i will make the purchase as sson as someone can help me confirming this. is there anything that i'll need?

so far i had my car for about 7 years, i have only changed the O2 sensors, the MAF and the ignition key switch myself. i don't even consider myself qualify as a weekend warrior (DIYer). but since i was also laid off last week, money is a little tight. is this something i can do myself? can someone send me the post if someone has already posted before? if not, does anyone knows what is the approx. labor cost at a shop?

thank you all in advance for helping me.

LINK

third pic shows a J-tube, if yours doesn't look like that then you need the Y-tube!

I replaced mine a couple of years ago and took me about 4 hours and was the first job I did on a Boxster. You will need to access the engine from both top and bottom so axle stands are a 'must have'.

Edited January 28, 2009 by HairyPotter

[shihman]

2000MY, Boxster S, 100800miles.

hi guys, last friday morning when i go start my car, a big puff of smoke came out. i thought i blew my engine. then the smoke slowly burned away. so i did a search here and all the symptoms point to a failed AOS. Along with the big white puff of smoke, i also felt lose of power lately and a fluctuating engine speed when idling.

after some search i found the part number for the AOS (996-107-023-04) but i need someone to confirm with me that i will need a Y-tube NOT a J-tube correct? i will make the purchase as sson as someone can help me confirming this. is there anything that i'll need?

so far i had my car for about 7 years, i have only changed the O2 sensors, the MAF and the ignition key switch myself. i don't even consider myself qualify as a weekend warrior (DIYer). but since i was also laid off last week, money is a little tight. is this something i can do myself? can someone send me the post if someone has already posted before? if not, does anyone knows what is the approx. labor cost at a shop?

thank you all in advance for helping me.

LINK

third pic shows a J-tube, if yours looks doesn't like that then you need the Y-tube!

I replaced mine a couple of years ago and took me about 4 hours and was the first job I did on a Boxster. You will need to access the engine from both top and bottom so axle stands are a 'must have'.

thanks Hairy, i read the link you sent me and i also found few other links said that on a 2000MY and up model, you can access the AOS from top only. is this correct?

[fasterjames]

thank you all in advance for helping me.

LINK

third pic shows a J-tube, if yours looks doesn't like that then you need the Y-tube!

I replaced mine a couple of years ago and took me about 4 hours and was the first job I did on a Boxster. You will need to access the engine from both top and bottom so axle stands are a 'must have'.

thanks Hairy, i read the link you sent me and i also found few other links said that on a 2000MY and up model, you can access the AOS from top only. is this correct?

No you will need to access it from under the car too. You will remove the right rear wheel and jack it up in order to remove an accordian style hose and 2 bolts that connect the AOS to the engine block. Replacing the AOS is really not very difficult other than access to everything is very tight. One word of caution I learned the hard way: do NOT break the little clip that attaches the 'middle' hose of the AOS to an oil line of some sort. After much investigation I found out the only way to fix it is to buy a new clip-molded hose which Porsche gets 7.5 hours to replace. Save yourself lots of headaches. I ended up rigging it closed since I could find no evidence of it being a high pressure hose.

[shihman]

thank you all for all your input. as i said before, i was recently laid off and my plan is to get this fixed and sale it. i love this car and i hate to let it go. but this car is just any many other high quality, high performance car. it is very durable but its getting to the age where many original parts has to be replaced and the fee is just too much for me to up keep, especially now.

so, i'll go ahead and order the AOS and the Y-tube. is there anything else that i'll need?

[1schoir]

thank you all for all your input. as i said before, i was recently laid off and my plan is to get this fixed and sale it. i love this car and i hate to let it go. but this car is just any many other high quality, high performance car. it is very durable but its getting to the age where many original parts has to be replaced and the fee is just too much for me to up keep, especially now.

so, i'll go ahead and order the AOS and the Y-tube. is there anything else that i'll need?

The factory manual recommends that you use a dab of "Syntheso Klube" (sp.) which is a very expensive tube which contains nothing more than a lubricant, and it is meant to facilitate slipping the various rubber and plastic pieces on. The tube has enough to do about 500 AOS replacements.

You can use any lubricant which does not attack rubber. If you are not concerned about longevity, any lubricant at all will do.

I would also recommend that you get a pair of hose end pliers (Sears has some good, inexpensive ones), so that taking the factory clamps off and on does not become a complete PITA. You need the type that clamps and locks on so that you can easily manoeuver the clamps in place. Especially the lower clamp on the bellows.

Regards, Maurice.

[Glyn]

I dont think the problem you describe is your AOS.

The AOS allows air and oil/combustion fumes to be fed to the throttle body intake to be burned and shoved out via the exhaust- You describe first starting - AOS will not produce the smoke from a cold start, a failed AOS is most significant once the engine is up to operating temperature as the oil mist in the engine increases with temperature the AOS goes about its work in seperating the oil mist from by passed combustion gasses - On a cold start there is no mist and the AOS cannot feed oil directly from the sump - like a pump.

Had you parked your car in a different position from your normal parking? _ I say this because the horizontally opposed engine is suseptable to oil getting into the cylinders after it has been parked on an incline (side to side - not front to back)

Three cylinders point to the left and three to the right, when you park on a side to side incline the oil as it returns from high in the engine drips back to the sump but some drips into the cylinder bores behind the piston, once the engine cools the pistons return to their normal slightly oval shape - this oval shape allows accumulated oil to seep past the oil control scavenge ring and the piston rings - which in turn burns on cold start up.

The reason for the oval shape of a piston is to allow for expansion of the alloy when it is heated - pistons are attached to the connecting rod by the small end - the forces exerted on the piston at these points are considerable so more metal is needed to do the job,(more metal=more expansion) much more metal than around the sides of the piston - hence the ovalness - once hot the piston expands to a round shape which provides a good seal

Edited January 29, 2009 by Glyn

[shihman]

wow glyn, i didn't see that coming. you just threw a monkey wrench into my plan (no pun intended). so you think my problem is not the AOS. i am so lost now. i always park my car in the garage and it is relatively flat in all 4 directions. the puff of smoke thing just started last friday. it doesn't matter where i go or how long i park the car, there is always smoke at the start up no matter if it's a cold start or after the engine warms. what do you think it's the problem now? i just ordered AOS and the y-tube from Sunset today.

please help...

[RFM]

Since you ordered a new AOS, i would replace him anyway, and recheck for smoke after a day or two. At the same time, clean the throttle body and intake manifold as good as possible from oil residues.

[Glyn]

wow glyn, i didn't see that coming. you just threw a monkey wrench into my plan (no pun intended). so you think my problem is not the AOS. i am so lost now. i always park my car in the garage and it is relatively flat in all 4 directions. the puff of smoke thing just started last friday. it doesn't matter where i go or how long i park the car, there is always smoke at the start up no matter if it's a cold start or after the engine warms. what do you think it's the problem now? i just ordered AOS and the y-tube from Sunset today.

please help...

Ah ha - You have now explained a little further, It doesnt matter how long you park you still get the smoke - I guess it could be the AOS as oil accumulated in the J/Y tube could be being sucked in on start up.

Is it smoking everytime you start - and if so is it smoking all the time whilst its running - I just dont understand how the AOS could not smoke during normal running then dump oil in the Y/J tube once switched off.

My original post regarding the incline - It is typical of people to think they have an issue when they get a cloud of smoke on start up if they are not aware of the characteristic of the engine design. You have now confirmed you park on a flat surface and always have done so the incline theory would not apply.

If the car is running fine in all other aspects then I would agree the AOS is the faulty part, sorry if my first post caused concerns - i read your problem and from the information available I didnt want you to panic or spend money having something fixed that didnt need it - all too often people go on holiday (Vacation in your terms) in their car - get this smoke problem and assume this is a fault when all it is is the incline issue

[shihman]

thank you all again. i'll try to make the description of the problem more clearly next time, if i still have the car. also thank you for explaining the characteristic of the engine design. so i will not panic next time. ;)

some of my confusion after doing some research here is also exactly what you said about having smoke while driving. but i didn't notice much smoke if any at all after the initial start up (cold and warm). and the fluctuation of the engine during idling goes from 9000 to 2000 and back to 9000 rpm for 3 or 4 times then it will stop and stays around 9000. i had to replace my MAF few years back and may be i need to replaced it again because of the AOS.

ok, so i'll proceed as planned to get the AOS replaced and report back here. Hopefully that will fix the problem.

thanks,

[Glyn]

The Maf is well away from the AOS tube so the AOS cannot interfere with it so i would discount that, I also think you mean your revs are 900 to 2000.

Not sure on your model year if you have the e-gas or cable operated throttle

If e-gas check all the rubber pipework and clips that feed the air from the filter to the throttle body - if there is a leak this will cause the erratic revs at idle on a cold start - but dissapears once warm (This makes a weak mixture and the oxygen sensors detect this then richen the mixture then back off again as the MAF should be doing some of this work and if air is getting in upstream of the maf it wont be able to account for the volume of air or indeed estimate the mixture requirement)

If cable opperated throttle then clean the throttle body and the idle speed control valve - this should settle the revs down

Do let us know how you get on - and remind us all just what a pig of a job fitting the AOS is (very fiddly)

[shihman]

i do have an e-gas. i know for fact because i had to replace one few years back.

what you described is exactly how it is. oh and there is another thing i failed to mention (failed like my AOS). i have a cel comes on and off for few weeks now and i finally went to my local auto zone and got a P1130. it indicates a leak some where or a failed O2 sensor. how do i check whether it's a bad O2 or a leak?

[Glyn]

It could be either - the sensor could be "Tired" but then again it could be perfect and is reporting what it finds, I suspect the sensor is fine as the problems you describe do indicate a weak mixture.

Not sure which tester was used to get the fault codes - I have the Durametric and it reports an oxygen sensor that is slow to respond (as it gets older) as "Tired" some time later it reports a fault code - which sort of indicates the sensor has finaly had it.

Take all the air trunking pipework from the air cleaner to the throttle body out - check it for splits - check the rubber seals and clips, make sure there can be no air entering the throttle body that has bypassed the MAF (MAF is next to air filter)

Whilst the air trunking is out of the car clean the throttle body - and pay attention to the butterfly flap where it meets the throttle stop position - gum in this are can leave the throttle butterfly open just a little - the gum also is sticky so the throttle closes- the e-gas system maintains the revs but needs to open the butterly to do this - if its sticky the throttle opens more than it needs to as it breaks away from the stickyness - the revs rise too far then the throttle closes itself again - and so it repeats.

Dont worry about throttle cleaner or propriety stuff - you will find the body will clean perfectly well with brake fluid - but dont spill any on paintwork - it will lift the paint.

You have a nice days work ahead - enjoy it and the satisfaction when you have done the job will be as exhillarating as driving the car.

Let us know how you get on

Edited January 30, 2009 by Glyn

[shihman]

thx glyn. i am sure this may be all very to you guys just as you can type out the instruction so easily. i too wish i am that knowledgeable. :huh:

like i said in the earlier thread, i am barely qualify as a weekend DIYer. so i have few questions and concerns in order for me to do this. will i be able to access everything from the top without jacking up the car? do i need to purchase any parts ie. hoses, clamps, in advance because this is my only car and if i have to take it apart, i will not be able to go any where. now, after i take it all apart, is it pretty straight forward as far as putting everything back together? may be i need to do a search for a exploded diagram on a boxster engine.

[1schoir]

thx glyn. i am sure this may be all very to you guys just as you can type out the instruction so easily. i too wish i am that knowledgeable. :huh:

like i said in the earlier thread, i am barely qualify as a weekend DIYer. so i have few questions and concerns in order for me to do this. will i be able to access everything from the top without jacking up the car? do i need to purchase any parts ie. hoses, clamps, in advance because this is my only car and if i have to take it apart, i will not be able to go any where. now, after i take it all apart, is it pretty straight forward as far as putting everything back together? may be i need to do a search for a exploded diagram on a boxster engine.

Everything that Glyn describes can be accessed from the top. No need to get under the car for these procedures. There will also be no need for any other parts, unless after you take it all apart and inspect you find a tear or rip in one of the tubes or one of the clamps is broken. In that case, you can still put everything back together, get the new part that you found was defective and do it again. No fun, but if it's your only car and you can't see anything split or torn before taking it apart you don't have much choice.

As far as an exploded diagram, if you have a digital camera, take a bunch of photos before you take anything apart and you'll have no problem putting things back together in the right order (although some of those parts have to be wrestled with for a while).

In any case, here are a couple of diagrams which should help orient you (Click on the diagrams to blow them up so that you can see the various parts more clearly):

Part #4 is the air filter cartridge. Make sure all of the clips that hold the air filter housing shut around the air filter cartridge are properly fastened.

Among these parts, part #9 (air sound baffle) may give you some difficulty because there is not much space between it and the underside of the engine compartment perimeter.

Also, if you look at where the arrow points to the butterfly valve, you will see a horizontal "rod" immediately above the arrow. Where that rod connects to the throttle body and pivots, both on the left and on the right, is where you should make sure that you spray plenty of cleaner. That is where it sticks, along with where the whole circumference of the butterfly plate contacts the throttle body.

Regards, Maurice.

Edited January 30, 2009 by 1schoir

[shihman]

you guys are awesome. :notworthy: tomorrow suppose to be a really nice day here in dallas and i'll set aside a whole day to do this. my AOS parts won't be here until next week but at least i can familiar myself around the engine first.

i'll report back and let you guys know how i went for me.

thank you bunch.

[Glyn]

Nice diagrams from 1schoir there to help you Shihman.

Just dont be afraid of doing the work, I like the tip about using the digital camera too so you have a refference if you get stuck - to be honest the job sounds daunting - but if you have a basic tool kit and are able to fit a plug on an appliance then you can do this job.

Have a good long look at the area of work and take those photos, work cleanly and methodically - think about everything you are doing, it is a fiddly job because of access - leaning under the clamshell etc but a couple of bed sheets over the rear wings (think you call the wings something different over there - the panels with the rear lights in it, had to return to edit it as its the fender! _ Im learning) to prevent any scratching of the paintwork as you move about.

Now when the job is done start her up and be impressed with your work - no more fluctuating idle, have a beer and reflect in your new skills - you have two hands like all of us so you can do the job - and also be impressed at how much you have saved from not taking it into the dealer - you will find many jobs can be done at home and this makes ownership costs very affordable.

You will aslo find many enthusiasts on this forum will come to the rescue should anything go wrong or is genuinly beyond your confidence levels if they are fairly close to where you live.

This forum is a terrific forum but also check out Boxa.net - which is well supported and also has some very knowledgable enthusiasts - though you do need to be a little thick skinned due to the humour.

All the best in getting the job done and let us know when youve done it

Edited January 31, 2009 by Glyn

[shihman]

ok guys, with your help i was ready to tackle this task.

after i remove the engine cover, first thing i noticed is the dark color spot on the engine (see picture 1 circled in red). it looks like an oil leak or some sort. should i be concerned? is this a major problem and could this be reason for the smoke?

second, i removed the main trunk from the air filter housing to the throttle body. i noticed there are some oil inside the trunk dripping from the butterfly valve (see picture 2). the trunk and both ends seem fine with no cracks and the seal was very tight when i try to remove it. a side note, from the diagram, my trunk do not have an air sound baffle attached to it.

now do i need to take the throttle body apart to clean the valve, since the valve is pointing downward? or do i just spray the cloth with cleaner and try to clean the gum off the valve as much as possible, there is a very thick layer of gum.

please advice on how to proceed.

thanks a bunch.

[1schoir]

ok guys, with your help i was ready to tackle this task.

after i remove the engine cover, first thing i noticed is the dark color spot on the engine (see picture 1 circled in red). it looks like an oil leak or some sort. should i be concerned? is this a major problem and could this be reason for the smoke?

second, i removed the main trunk from the air filter housing to the throttle body. i noticed there are some oil inside the trunk dripping from the butterfly valve (see picture 2). the trunk and both ends seem fine with no cracks and the seal was very tight when i try to remove it. a side note, from the diagram, my trunk do not have an air sound baffle attached to it.

now do i need to take the throttle body apart to clean the valve, since the valve is pointing downward? or do i just spray the cloth with cleaner and try to clean the gum off the valve as much as possible, there is a very thick layer of gum.

please advice on how to proceed.

thanks a bunch.

On your Boxster, the sound baffle is there but it is just integrated into the overall intake tube.

No need to take the throttle body apart unless you want to get more involved. Put a wad of cloth in front of and below the throttle body opening while you spray the cleaner into the opening. As you spray the cleaner in there, scrub it with an old toothbrush whose shape you can adapt to the angle you are working with. You can heat the neck of the toothbrush with a heat gun or hair dryer and then easily bend it to the shape you need. Before you use the toothbrush, make sure to test its bristles with the particular solvent you are using to make sure that the bristles don't "melt" and cause a bigger mess.

In a way, it's good news that you found the thick layer of gum, because that means when you clean it up you should get a much smoother idle and throttle response. If you use the right solvent (whether it's brake parts cleaner, or something made for dissolving gum deposits, such as "Gumout") you should be able to get the throttle body opening and the butterfly valve absolutely sparkling. Just keep at it, and don't breathe in too much of the fumes! :P

As far as your first photo, you should try to isolate the source of the "wetness". If there is nothing obvious, clean the surfaces thoroughly, then, after you are done with cleaning the throttle body, button it up and see what results you get. After that, if you monitor the surfaces you have cleaned, you should be able to isolate the source, which maybe just a loose clamp, or disconnected line.

Also, the wet area in your first photo, is more or less located further to the rear, but nonetheless not too far away and also above the area where the AOS bellows is vertically located. See if you can reach the bellows and feel around it to see if there is a split there.

You can also see some wetness in your photo just behind and to the right of the throttle body. That looks like it's either caused by a loose clamp. or again maybe coming from the direction of the AOS bellows, which is closer than the other totally wet area in your photo. Try tightening all of the clamps that you can see around both tubes, forward and rear.

Here is a photo of the AOS with the red arrow pointing to the bellows (again, click on the photos to blow them up):

(The yellow arrow is pointing to the other part which gets pressed in to the engine block with some of that lubricant when you get ready to install that new AOS that you have coming).

Here is a photo showing the location of the bellows when it is installed on the installed AOS:

This photo is taken with the right rear wheel off, the car up on jackstands, and you are looking up through the wheel well, at about a 45 degree angle, on a diagonal, in a line, say, toward where the steering wheel is inside the car. My drop light is hanging down just above and to the left.

The red arrow points to the bellows.

The yellow arrows point to the the two 10mm bolts that secure the AOS housing to the block (the bottom bolt has not yet been tightened).

The blue arrow points to two heavy zip ties that I used to hold the factory clamp open while I pressed the bottom of the bellows onto the protrusion in the block. I later cut the zip ties to release the clamp in place. This is the reason I recommend those Sears hose clamp pliers, but it can be done this way in a pinch if you have heavy duty zip ties handy.

Keep up the good work! :clapping: You are almost there.

Regards, Maurice.

Edited January 31, 2009 by 1schoir

[shihman]

hey maurice, thank you for your quick response. i cleaned the butterfly valve and the all the oil off top of the engine. and it turns out that the color of the part is black to begin with (duh...) and there actually wasn't that much dried oil on it. so i reconnect the trunk back on to throttle body, that's a ***** try to put it back on, and the air filter housing.

then i went to investigate and familiarize myself with the AOS, i think i found the culprit to my problem. the hose next to the top of the AOS has a crack (see picture. the red circle indicates the crack and the yellow is the top of AOS correct?) i don't know what this hose connects to. i tried to follow it but again with my very limited knowledge, i have no idea where it leads to. so, here are more of my stupid questions, is it likely this is the cause for cel P1130, vacuum leak, and the big puff of smike at start up? is it likely that my AOS is still good (i'll still change it out when it comes next week)? lastly, hose this cracked hose, is it safe for me to drive my car, just locally and short distance?

thank you all for the instruction, encouragement and patience. i do feel rejuvenated and definitely have more confident to work on my car more. i can't say enough about this forum. whomever started this needs to get a medal of honor. :thankyou:

[1schoir]

hey maurice, thank you for your quick response. i cleaned the butterfly valve and the all the oil off top of the engine. and it turns out that the color of the part is black to begin with (duh...) and there actually wasn't that much dried oil on it. so i reconnect the trunk back on to throttle body, that's a ***** try to put it back on, and the air filter housing.

then i went to investigate and familiarize myself with the AOS, i think i found the culprit to my problem. the hose next to the top of the AOS has a crack (see picture. the red circle indicates the crack and the yellow is the top of AOS correct?) i don't know what this hose connects to. i tried to follow it but again with my very limited knowledge, i have no idea where it leads to. so, here are more of my stupid questions, is it likely this is the cause for cel P1130, vacuum leak, and the big puff of smike at start up? is it likely that my AOS is still good (i'll still change it out when it comes next week)? lastly, hose this cracked hose, is it safe for me to drive my car, just locally and short distance?

thank you all for the instruction, encouragement and patience. i do feel rejuvenated and definitely have more confident to work on my car more. i can't say enough about this forum. whomever started this needs to get a medal of honor. :thankyou:

You are most welcome, and good work!

What you have circled in yellow is definitely the top of the AOS.

The other tube with the crack outlined in red is, I believe, the oil fill tube. That tube usually comes in three parts, and the part that you highlighted is the middle tube and it usually has a "mesh sock" over it to protect it from chafing. If it is the oil fill tube, that can cause a CEL due to the vacuum leak. See if you can follow the tube towards where it would come through the firewall between the engine and the rear trunk in the vicinity of where the forward face of the coolant tank where it is mounted on the trunk side of the firewall.

Here is a photo of that section of the oil fill tube in my 97 Boxster (NON E-gas) showing the mesh sock:

The red arrow points to one of the connections of the three part oil fill tube.

The yellow arrow point to the mesh sock covering the part of the tube that I think is cracked on your car

The green X is on the AOS, although this is a photo of the old style (horizontal top part) AOS that was on my car before I replaced with the one shown in the photo I posted in my previous post.

Signs of a failing AOS (aside from the obvious MASSIVE cloud of white smoke) are excessive suction when trying to unscrew the oil fill cap and oil residue sitting in the throttle body. Go to Mike Focke's website for more info and photos about the AOS, here : http://mike.focke.googlepages.com/airoilseparatorreplacement

If you have finished cleaning the throttle body thoroughly, you can try a temporary fix on that oil fill tube to see if your idle and throttle response problems are cured. You can either try to seal the crack with some silicone sealant (after thoroughly degreasing the edges of the crack), but you then have to wait until the silicone cures so none of it gets sucked into the engine, or try to put a small flexible dense foam patch on it and wrap it up tightly with tape. This is only a temporary fix just so that you can determine if the engine is running properly now. There are a couple of threads on this forum about replacing the oil fill tube, with the part numbers.

Regards, Maurice.

[shihman]

hey maurice, defiantly is the oil tube. although i am not sure if it is the middle part (doesn't look it has 3 parts, only 2.). it does have the connection you showed in you pic. but mine does not has the mesh sock but it has a coil like bending section towards the firewall/side of the coolant tank.

where can i get those temporary fix you are talking about, autozone? the silicone sealant or the flexible dense form patch and tape (preferred?)? is the car drivable before i seal the crack because i'll need to drive to local auto store to get them.

[1schoir]

hey maurice, defiantly is the oil tube. although i am not sure if it is the middle part (doesn't look it has 3 parts, only 2.). it does have the connection you showed in you pic. but mine does not has the mesh sock but it has a coil like bending section towards the firewall/side of the coolant tank.

where can i get those temporary fix you are talking about, autozone? the silicone sealant or the flexible dense form patch and tape (preferred?)? is the car drivable before i seal the crack because i'll need to drive to local auto store to get them.

You can get the silicone sealer at Autozone. The one that I like to use is Permatex Black Silicone Adhesive Sealant (Item # 81558, 16BR) 3 oz. tube.

The dense foam patch you can look around for at Autozone or at Home Depot. You only need a small rectangle, like 2" by 3" or enough to more than cover the crack and conform to the curvature of the tube. You can temporarily use electrical tape to wrap it on there because it stretches and will allow you to make a tight seal.

As far as driving the car, you were driving it before you discovered this crack, so I imagine you can drive it now with no problems. Some Autozones will also let you borrow their code reader to read and then erase the codes (not in California).

Let us know if your idle and throttle response has improved or changed.

Regards, Maurice.

[Glyn]

Well done Shihman - from your rather apprehensive start you had the balls to get on with the job, The oil and gunge around your throttle housing confirm the AOS has had its day so get that changed.

Tape the split over for the time being and start up the car - your tickover should now be steady and once you change the AOS no more oil will get to the throttle body so it will be years before the deposits build up again.

Maurice has certainly provided you with excellent advice, schematics and photos - plus the additional support and encouragement - this is what these forums are about, and despite whatever we all like to think we know about the Boxster there is always someone with more experience in a particular area - in short we all seek help or ideas from time to time.

enjoy the car (hope you keep it) and give yourself a big pat on the back for getting stuck in.