When the AOS is failing ?

[SithPitt]

I'm giving a good tune-up to my Boxster... I've read in RennTech about the AOS, but what are the symptoms to be replaced ???

Sometimes when I cold-start my car a huge smoke comes out the exhaust, but that's it... No major or noticiable oil comsumption... I checked the line that goes to the Throttle Body, but a little oil, no gunk there neither in the plastic intakes that says "PORSCHE"... As I'm doing this "Major Tune-Up", it is recommended to replace it ???

[1schoir]

I'm giving a good tune-up to my Boxster... I've read in RennTech about the AOS, but what are the symptoms to be replaced ???

Sometimes when I cold-start my car a huge smoke comes out the exhaust, but that's it... No major or noticiable oil comsumption... I checked the line that goes to the Throttle Body, but a little oil, no gunk there neither in the plastic intakes that says "PORSCHE"... As I'm doing this "Major Tune-Up", it is recommended to replace it ???

The smoke on startup is not necessarily indicative of a problem with the AOS, and in some instances is perfectly normal because of the horizontally opposed layout of the engine.

As far as replacing it, if you don't have any of the usual symptoms of a failing AOS you might take into account the mileage on the car before you decide on whether to include it in your "Major Tune-Up".

Regards, Maurice.

[SithPitt]

Thanks, Maurice, but then which are the commom AOS failure symptoms ???

[1schoir]

Thanks, Maurice, but then which are the commom AOS failure symptoms ???

Do a search here and you will find the topic covered in detail.

The ones that come to mind immediately can include an oil filler cap that is very difficult to unscrew because of excessive vacuum, deposits of oil in the throttle body, unsteady idle, large cloud of (usually white) smoke that can cover an entire block, cut bellows and oil deposits in the surrounding area.

You can also read more about the AOS and a DIY on its replacement on Mike Focke's Boxster Pages, here: http://mike.focke.googlepages.com/airoilseparatorreplacement

Regards, Maurice.

[Glyn]

What are you doing to the car to "Tune it up"?

Cars used to be "Tuned" when they had distributors, carburetors, adjusting tappets, ignition timing but modern cars all have an electronic brain that keeps everything in check.

Unless of course you are remapping and fitting extra stuff

[SithPitt]

I'm sorry if sounds like re-mapping or something else, but I was referring to a "General Maintenance"...

I did the following:

1. Clean Throttle Body and Mass Flow Sensor.

2. Engine overall clean-up.

3. Replace the Spark Plugs & the 6 Coils.

4. Replace Water Pump & Thermostat.

5. Replace Serpentine Belt.

6. Change Oil & Oil Filter.

7. Replace Fuel Filter.

8. Replace Air Filter & Cabin Air Filter.

I think it's enough and around $600.00... I'm waiting for the headers ( :D "