Flat6 Innovations

The first thing I'd do is look at fuel trim. If the engine is running rich, it will consume oil, as fuel is solvent, not lubricant. Rich engines will consume oil.

The other test that can be performed to test both ring seal, and the AOS is a manometer test. The DFI engine should test at 16" of water column , and can be slightly higher at sea level, and slightly lower at elevation.

I have been seeing, and repairing these issues since 2010. Identifying the condition is fairly difficult, but at times I have had good luck with a horoscope inspection with the sump plate removed, sneaking inside the cylinders from below.

Leak down and compression tests are NO GOD for this! Why? Because the oil thats being consumed will over lubricate the cylinders/ pistons and will seal the rings up to the point that it will have higher than normal compression, and lower than normal leak down. This will falsely let the unknowing tech believe that the issue does not exist.

This one will fool most.

GT2RSobsessed

I followed up with the service dept at Porsche of Larchmont. They told me to contact them when my low oil light indicator goes off (not in 1000 miles). The thing they look for in oil consumption is mileage, specifically how many miles it takes to use a quart of oil. They stated if the air oil separator were bad, I would see heavy smoke coming from the exhaust, and have audible sound, which I do not (besides the sound from the Sharkwerks cross pipes and Fister exhaust).

Iceter

Wouldn't you be able to tell from the condition of the plugs whether the root cause was a rich condition or injection of oil into the cylinder?

I'm no Porsche tech and I know that a modern computerized ignition can compensate somewhat for non-ideal combustion conditions, but on a small block ford, it's pretty easy to see the difference on the plugs between an engine that is running rich and one that is getting oil into the intake charge.

I am not arguing--just inquiring.

Flat6 Innovations

What they have done is the common sense way to measure oil consumption, and it works well.

The AOS can fail in several ways, and if the car is a base, or an S, the symptoms differ, as the AOS units are not the same, and not even mounted in the same places.

Heavy smoke, and the audible sounds are not always a symptom of a failing AOS. The proper way to measure the health of the AOS is to use a Manometer test, this is something the dealer will not tell you to do, however, this is common place with BMW engines.

Tony Callas, my partner at The Knowledge Gruppe, where we train technicians came up with the procedure for using the Dwyer 476A Manometer to test for a failed/ failing AOS. The proper reading for a healthy AOS is 5" of water column, and this can vary up to about 6" and the unit still be ok. If the values are higher than this, then the AOS is failing.

If the values are lower than this. in my experience, the engine has a ring sealing issue due to failed or failing cylinders/ pistons/ rings. It is also possible that the engine has excess fuel trim washing the cylinder walls down, compromising ring seal.

This should be the proper tests to run moving forward. Leak down and compression tests will tell you little to nothing, since excess oil in the rings will force them to seal during such tests, giving a false negative result.

Did the dealer check fuel trim? If so, what was it? This should have been the VERY FIRST thing that was done, as a rich engine has an issue, and will consume oil- period.

Plug readings with these engines don't show much at all with today's fuels. Fuel trim is the proper diagnostic method, along with reading lambda from the primary O2 sensors.

gopirates

I was told by the SA the tech measured vacuum level in the crankcase via the oil filter to determine the AOS was failing. Keep in mind I have a base.

I also seem to recall he mentioned the threshold should be 7 and mine was measuring 13.

Does this make any sense?

Flat6 Innovations

Yes, they did use a manometer, then. If the reading is a 13, then the AOS is almost positively failing. To me, even 7 is very high, I like no more than 6. With the elevation of Raleigh, you should be at a 5.5 optimally.

gopirates

Thanks for all the input and confirmation Jake. I take the car back in on Monday. Is there anything else I should be asking for them to look at further? I have already asked them to look at the plugs when they get it.

Flat6 Innovations

What year is your car?

Iceter

I believe his car is an '09 C2.

gopirates

Yes, '09 Base C2 Cab

gopirates

Update. I got the car back today after the AOS was replaced. We are still monitoring the oil consumption. They pulled a plug and said it looked ok, though I am due for a major in September and recommended they should be changed then. They also said the vacuum test was measuring at 6 now.

I'll be able to detail it this weekend and will then see if my pipes still get sooty and will keep an eye on everything.

Dan GSR

Thx, keeping an eye on this thread. I may have same issue

JayRace

What are you connecting the manometer to when you test?

jchapura

I purchased an extra oil filler cap and drilled a hole and epoxied in a hose-barb nipple. Be prepared to clear CELs - I found that misfires were generated when I removed the cap while the engine was running. I found my vacuum to be about 3.5 inches of water at an elevation of 515 ft. That seems low. Can anyone comment on that?

gopirates

The dealership does it with their gear. Maybe I misheard them when they described what they were doing, though I thought they said the tested through the oil filter. I think we need Jake to provide clarity on this one...