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Severe oil burning issue, detailed post

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Old 02-25-2017, 10:41 PM   #1
VadRad
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Default Severe oil burning issue, detailed post

Hi guys,

So I am in need of your wisdom, as I am at the end of the road here with any and all ideas as to why I have extensive oil burning issues. The dealer has provided very little assistance and just says it can be anything. Below is a list of all the background, details, and testing to date. I hope that one of you uber techies can assist.

1. Car is a 2006 Cayman S 6 speed.

2. Burnt absolutely no oil from new till about 50k miles. All of sudden at 50k miles started to burn 1 quart per 600-800 miles. Heavy carbon deposit on rear bumper and tailpipes.

3. Oil changes intervals varied from 1 - 2 years with roughly 15-20k miles between oil changes, as per Porsche maintenance placard. Car was daily driven.

4. No previous technical issues with car aside from waterpump failure at roughly 45k miles.

5. I did some research and changed my AOS, as this seemed to be a common culprit in many cases. This had no impact on my oil burning consumption.

6. Had dealer do full inspection on car at ~60k miles. Dealer indicated that all cylinders were scoped with no scoring found. Cylinder 4 had minor oil pooling, but no cause could be determined. Plugs had light buildup of carbon. Pressure test done on cylinder 4 with loss of 6 PSI at 90PSI, vs cylinder 5 with loss of 5 PSI at 90 PSI. Crankcase and exhaust pressure all within specification. Dealer indicated they didn't know what was wrong and to just continue driving car.

7. Oil and filter sample results were sent for analysis around the same time. Oil was 18 month old and had 15.5k miles on it. Concerning results came back as follows.
a. Aluminium 10 ppm.
b. Chromium 3 ppm.
c. Iron 51 ppm.
d. Lead 11 ppm.
e. Silicon 21 ppm.

7. Car recently, at 80k miles, started to surge a bit on startup and throw engine code P0421 (warm-up catalyst efficiency below threshold bank 1). I drove the car like this for a few days as it was completely drivable and I couldn't make it into the dealer. I then parked the car for 4 days, after which when I started the car it ran really rough, was misfiring, and threw codes P0302 (cylinder 2 misfire), P0421, P0431 (catalyst efficiency bank 2), P0300 (random misfire). The car was underivable and I towed it to the dealer.

8. Dealer found all 6 spark plugs completely black (carbon) and dry. Found oil pooling in cylinder 2, but not in other inspected cylinders. Further inspection found intake header and MAF covered in oil, which required cleaning as engine wasn't operating at higher RPMs. Plugs all replaced, oil changed, and oil cleaned from intake system. Dealer stated that they are unsure as to what caused this, and to keep on driving car. Please note that I recently replaced the plugs, so these fouled plugs only had 20k miles on them. I also replaced all the ignition coils about 4 months prior to this event.

9. I took the car home and it ran perfect, but oil is still burning. I actually always used Mobil 1 0W40 per Porsche spec, but after this last issue asked the dealer to switch it to Amsoil Euro Spec 5W40, as I heard a lot of guys stated it didn't have high consumption like Mobil 1. I checked the oil level and it dropped 1 bar within 60 miles, so I am not sure I am having any different luck with a different oil type.

10. I then recently parked the car for another 6 days and started it without any issues. It ran fine with no hessitation or surging. I also re-rechecked the AOS by opening the engine oil cap and there is very little vacuum, so seems like AOS might be okay. I also noticed that if the car is parked for maybe 1 day, upon startup I get a plume of white smoke but it subsidies after a few minutes to a very small amount.

I don't really know what to do next as the dealer thinks it might the piston rings, and feels that air intake system contamination could have been due to over pressurization of crankcase and sucked in by PCV valve. Dealer did not do any other tests or suggest any other course of action aside from what I mentioned. Dealer just says to keep on driving it like this, which obviously doesn't seem like a very reasonable statement. Unfortunately I only have one dealer in the city and can't get a second opinion aside from aftermarket shops.

I was just thinking maybe I need to do a leak down test on each cylinder, as I can't come up with any other ideas. The other thing is that all 6 plugs are contaminated with carbon, but if I had a specific cylinder issue then wouldn't I just have that cylinder's plug contaminated? Also having heavy oil contamination in the intake system seems like maybe something else is causing all of this and then equal distributing oil contaminated air into all 6 cylinders? I would greatly appreciate any assistance.

Regards,

VadRad
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Old 02-26-2017, 07:00 PM   #2
Spokayman
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Here are some thoughts about your situation here.

15-20K intervals for oil changes is way too long despite what the manual says. I believe the manual also says to change once a year at least.
The oil analysis is very high for all five of the elements you listed according to info that Blackstone Labs provides as "standard range".
Because of the long intervals and high metal readings I would suspect and investigate how much wear you have in the engine. Using a higher grade of oil along with a thicker range might help oil consumption a bit, but if the oil is too thick you may start to run into problems with the small oil passageways in the lifters and vario cam components.

Have you checked or changed your O2 sensors? Same question regarding your MAF? Both of these sensors, if dirty or defective, can cause running conditions that are too rich or too lean.

I believe a complete engine compression and leak down tests are a good idea and should help determine if there is a cylinder or two that's weak and how worn your engine really is.

Is it possible your AOS is still defective? The symptoms do sound like AOS symptoms, and despite the unit being changed and no excessive vacuum felt, maybe there is still a problem. Are the hoses leading to and from the AOS airtight and clear?

Putting it all together, the pooling oil, high metal content in the oil, excessive oil change intervals, white smoke on startup, oil consumption, etc. it sounds like premature engine wear to me.

Please note, these are just my guesses and thoughts based upon what I've read and understood about these engines. I am not a master mechanic.
I hope others will weigh in with their thoughts to help build some sort of consensus as to possible problems.
Please keep us updated on what you find out.
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Old 02-26-2017, 07:15 PM   #3
VadRad
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Thank you for the reply. I have not checked or changed the MAF or O2 sensors. The Porsche dealer recently cleaned the MAF as it was oil soaked and was throwing error codes under WOT >5000 RPM. After they replaced the plugs and did the cleaning the car has been running well, but obviously its only a matter of time before this issue re-surfaces.

I had Porsche do a compression test about 1 year back, but unfortunately I don't know if they did the entire engine or just 2 cylinders, as they provided values for only 2 cylinders. Everything seemed fine at that time as per the tech.

The dealer strongly feels the AOS is fine and doesnt want to test it. I am not aware of any oil or defects around the AOS at this time. I am going to have an indy shop test vacuum in multiple places to prove the AOS is functioning correctly.

I will likely have an indy shop do a full leakdown test, as currently its a bit of a wild goose chase. Please also note that I had this problem start at 50k miles and before that it burnt almost 0 oil over the entire change interval, and then all of sudden started to burn 1 quart per 600-800 miles. I agree with the theory of wear, but doesn't it seem a bit premature at 50k miles?

To add, I maintained the car to the tee as per Porsche maintenance placard. It does state that oil changes are 20k miles or 2 years. Regardless, it doesn't hurt to do them sooner.

I will keep you guys posted with progress.
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