AOS Question

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Hi guys,

I did a quick search & couldn't find anything on this specifically. My '01 Boxster started fine today but started smoking out of the tailpipe. I unscrewed the oil cap at idle & it came off easy with barely any change in idle. I did pull a P0420 & P0430 a few days ago.

Any thoughts or suggestions would be helpful.

[Loren]

What kind of smoke? blue, white, black?

Did it smell like gas or oil?

Those are pre-cat faults on a Boxster - could be oil?

Did you look in the throttle body for oil?

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It was hard to tell in the dark what color, I will check it tomorrow but it smelled more petroleum than coolant in nature. It could be oil, when I replaced the starter a few months ago I noted a bit of oil in the TB & intake pipes. I have also noticed the coolant going a bit low in the tank, but again this smelled more petroleum than a coolant smell.

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Well I got the TB & crossover tube off & this is what I found. Looks like AOS time?

Hmm, I can;t figure out how to upload photos, anyway it seems like a fair amount of oil in the intakes.

[Loren]

From the Help section...

"To start, press Click to Attach Files. A box will appear for you to select the file or files on your computer that you want to attach. Select the file or files you want to upload. You can select more than one file at a time by holding Ctrl (on Windows) or Command (on Mac) and click on the files.Once you have selected your files and clicked "Open", they will begin uploading. If there are any errors uploading the files, you will receive an error message, otherwise, you will see the attachments appear."

[btopping]

From the Help section...

"To start, press Click to Attach Files. A box will appear for you to select the file or files on your computer that you want to attach. Select the file or files you want to upload. You can select more than one file at a time by holding Ctrl (on Windows) or Command (on Mac) and click on the files.Once you have selected your files and clicked "Open", they will begin uploading. If there are any errors uploading the files, you will receive an error message, otherwise, you will see the attachments appear."

DOH!! OK here are the pics. Started taking the AOS out, figured since I have one on the shelf I might as well change it. Only issue so far is the pipe the the left side of the engine is being a bear to get released from the AOS & there seems to be a electrical connector bracket preventing the last 1/4" of removal. I'm gonna get some rest & tackle it again in the morning.

[JFP in PA]

You have a lot of oil in there, which is not a good thing. I would be looking at the AOS, but also checking that the oil scavenging pumps in the heads are working properly, or that the engine is not drastically over filled with oil.

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Is this more oil than a failed AOS would dump?

Are the scavenge pumps prone to a sudden failure & how does one test them?

[JFP in PA]

It would be best to start by replacing the AOS and carefully checking the oil level in the engine first as these are more common issues.

The scavenging pumps are mounted on the ends of the cylinder heads, and are self contained units that are driven by the cams. A lot like light bulbs, they either work or they don't. To check them, they have to be removed. Here are what one from an X51 M96 look like for example, you can see the drive tang that runs them:

There are two pumps, one each on opposite ends of the engine, and they are removed from the outside of the engine. If you have to get into them, remember that the two are not the same, they are specific to the cylinder head they came out of:

I would do the AOS, clean out the accumulated oil in the intake system and check the car's oil level before even thinking about the scavenging pumps.

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OK, I got the AOS changed (not all that bad of a job) & cleaned and as much of the oil out as I could.

Questions I have so far are:

1. Should I run a can of Techron through to clean the remaining oil film in the intakes?

2. Would a failing AOS trigger the P0420 & P0430 codes?

3. Would the car sitting on jack stands for a few days on the front only cause this?

[JFP in PA]

While Techron never hurts, it will not clean out the intake runners, as the engine is a port injection type, so the fuel enters the intake system right at the intake port. It will however clean off the injector nozzles, so it is not a bad idea.

P0420 and 0430 are three way cat codes for both banks and can be as the result of all the crud in your intake system. Once the AOS is fixed, and the intake systems cleaned out, clear the codes and take the car for a long, highway speeds drive so the cats get good and hot. That should clean them out

.

Sitting on jack stands, with the suspension hanging (not recommeded by Porsche), can cause issues with the suspension (corrosion on the exposed strut shafts), but will not do much else.

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I took the car for a 120 mile cruise yesterday & it ran great. No smoke, great power & best of all no codes. Oil level is the same, 1 segment below the full mark on the gauge, almost to the upper mark on the dipstick as when all this started.

[JFP in PA]

I took the car for a 120 mile cruise yesterday & it ran great. No smoke, great power & best of all no codes. Oil level is the same, 1 segment below the full mark on the gauge, almost to the upper mark on the dipstick as when all this started.

Good, you are back in business.

[logray]

Nice work!

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I took the car for a 120 mile cruise yesterday & it ran great. No smoke, great power & best of all no codes. Oil level is the same, 1 segment below the full mark on the gauge, almost to the upper mark on the dipstick as when all this started.

Good, you are back in business.

Yes. And thank you for all your help & advice.