LuckyKey

I'm having issues with my Porsche Cayenne and thought I would post to the pros and seek feedback/advice as to how to proceed.

I bought a used 2008 Porsche Cayenne S in the fall (225,000 kms), Sep 2016. After I bought it the garage I take it to indicated it was leaking a slight bit of oil...same garage the previous owner took it to. They said it's ok for now, but we would need to look at it in the future. I ended up buying a 12 litre pack of oil and have used almost all of it up over the last 3-4 months.

About 4 weeks ago the vehicle started to shake and the CEL came on, and eventually started to blink. I took it to the garage and they said it was the ignition coils. They said they had replaced 2 of the 8 last year, and replaced the other 6, of which they showed me the cracks in them. A couple of the plugs were black, but most wee ok, and not replaced. Move ahead 4 weeks and about $2k CDN, to now, and the problem is happening again. Same thing, shaking, CEL blinking.

I put my $5 Chinese scanner on the vehicle and noticed the following codes:

P0016 - Crankshaft Position - Camshaft Position Correlation (Bank 1 Sensor A) (which I also noticed a couple of months ago)...guess it was ignored

P0300 - Random/Multiple Cylinder Misfire Detected

P0308 - Cylinder 8 Misfire Detected

P0301 - Cylinder 1 Misfire Detected

Any ideas...before I go spending thousands more?

Thanks

TomF

I hate to tell you this, but it sounds like cylinder scoring. It has all the symptoms: blinking CEL, high oil consumption, fouled plugs, etc.. Incidentally, a blinking CEL means stop the engine immediately and don't drive it at all.

Do a compression check- at this point, I would suspect that you have significant issues with cyls 1 and 8. The compression check will show this very quickly. A compression check will not reveal early damage, only at the later stages of a cylinder scoring issue.

Sorry for your misfortune. Please keep us posted as to the results.

Best,
TomF

ScootCherHienie

Cylinder scoring was still an issue in the 4.8L engine in 2008?

Wisconsin Joe

Yes, although nowhere near as common as in the 4.5 non-turbo.

LuckyKey

Just heard back from the Indy...not good. Apparently the same cylinders were misfiring just before I purchased it, back in the fall, at 225,000kms; the old owner had it with the same garage, so I stuck with them. He said they flushed and treated back then and it was ok, until I put about 15,000kms on it. Now they're saying 3 options, rebuild engine, new engine, or flush and treat and sell it. I just spent 2k on coil replacement a month ago? Should they have known this was going to happen, and informed me, before it got to this point? Hard to believe.

nodoors

It does kind of sound like the previous owner might have sold because they noticed an increase in oil consumption.

What are the compression numbers?
What do you mean by flushed and treated?

If they are actually recommending to help you mask the problem so that it can be sold to an unwitting buyer, then they likely did that to you as well... yikes.

LuckyKey

Not sure about the compression numbers...I'll ask.

Flushing is some sort of cleaning, and then treatment. It's a band aid to a more serious problem, and I can't help but wonder if it was there before I purchased and they hid it from me. Would a compression test at the time have revealed the issue prior?

Sucks - this was my first Porsche experience, and a rotten one.

Curious, what would a used 2008 S V8 engine cost?

nodoors

If a compression test was performed and proved bad cylinders before you bought the car then it should have been disclosed to you before the sale. A compression test can be altered if the mechanic sprays oil directly into the cylinder before performing it. This is known as wet test. It generally is a way to check if the problem is with the rings/cylinder or the valves. If the number improves with oil then you know for sure it is the rings/cylinder...

1. Get all the information you can from them and past records from their shop concerning the vehicle, especially those compression numbers from both times if you can! Don't make any decisions on engine rebuild or replacement until you know the compression numbers.
2. Find out what the flush/treatment is that they are talking about. Sounds a bit dubious.
3. A used NA4.8 would probably be about $4-6k with average miles if you sourced it yourself. The labor to install is anyone's guess it can vary so much. Figure at least $5k.

LuckyKey

Found out that back in June 2016 cylinder #8 had oil that caused a CEL. Cylinder #1 and #8 had codes P0301 P0308...same as now. They cleaned and removed plug; flushed engine using 2 flushes; replaced oil and filter; fuel system service to remove deposits (222, 818 kms - June 2016)

Also found out that back in April 2016 the same cylinders triggered codes P0301 P0308, with a note that compression tests at that time said cylinders were consistent. 2 ignition coils and all spark plugs were replaced in April 2016 (218,000 kms).

I do not see a compression test for June or any other date following?

Sep 2016 (232, 717 Kms) - P0431 - warmup catalyst efficiency below threshold; Install 2 "I" tube extenders?

Oct 2016 (234, 000 kms) - CEL P1026 & P1021; replace high pressure fuel pump, cam stopper broken

Feb 14 2017 (241,000 kms) - P0016 & P0300b * p0301b; cylinders #1 & #8 misfires; replace 2 spark plugs and 6 ignition coils.

Mar 7 2017 (242,000 kms) - scan diagnose CEL - indicated they need to inspect cyclinders #1 and #8; however they are recomending the same flush treatment from back in the spring last year and sell it...or rebuild or buy a new engine?

Any advice / thoughts?

Hindsight is 20-20...should have asked for all of this back when I bought it in the fall. It passed the safety and emissions test up here so I thought I was good to go

nodoors

This is not good.

1. The cat was below efficiency because it is fouling up with oil. The I tube extenders are a way of moving the O2 sensors further out of the air flow to cheat the tests.
2. This is likely not legal where you are, but the emissions testers rarely check or find them because it is a theater to collect extra tax sort of like the TSA.
3. Fuel pump is unrelated. They commonly go out on these cars around this age.
4. As you have found now there is definitely an issue on cylinders #1 and #8. It is up to you how upset you want to be with the shop and or seller for not disclosing this. Sounds likely to be scored cylinders between the high oil consumption rate, fouled cat, and consistent oil fouling of the plugs.
5. I don't think a 'flush' - whatever that is they are doing is going to help you at this point. You could just keep replacing the plugs as they keep getting oil fouled and start planning for the big fix.

Do a compression test just to see the numbers. They are very easy to do.

You can also get a cheap, lit USB borescope on amazon that hooks up to your computer and look down inside the plug holes. When scoring gets bad enough it can be seen from the topside of the rings.

LuckyKey

Thanks for the feedback, appreciate it! The owner of the garage seems to think the flush treatment will buy another 20,000kms, as he believes it did before, and thinks selling it to someone else will make it their problem. My problem is that I'm not a scammer...and I am doubtful that it would work.

Question: how long do you think changing the plugs would get me? Is this something I could do regularly, along with feeding it oil, until I am ready to deal with the engine (i.e. find a used one)? If so, how often would I be doing it?

Btw, my son and daughter said they heard clicking from the front right (passenger seat). I've read this mentioned previously with the cylinder scoring stories. I'm not sure what it means?

I saw someone selling a cylinder head for my 2008 v8 S model, with 77,000 kms...would this be what I need to fix the engine problem?

Thanks again.

ScootCherHienie

If it really is cylinder scoring, the cylinder head is not involved... cylinder scoring happens to the engine block and pistons/rings. If there is oil getting into the cylinder from the VALVES... that comes from the cylinder head and solving THAT oil problem isn't all that expensive (new valve seals would likely stop the problem if oil is leaking past the valves into the cylinder). A compression check will tell you which cylinders have issues, but it typically won't tell you if the pressure loss is from a scored cylnder bore (in the engine block) or from leaky valves in the cylinder head. Some shops will have something called a "bore scope"... you remove the spark plug for a cylinder you think has a problem, and the bore scope provides light and a camera so you can SEE the sides of the cylinder, top of piston, and bottom of the cylinder head. If there is cylinder scoring, the bore scope would definitely "prove" that the engine block (cylinder bore) is scored. But it may not reveal if oil is leaking into the cylinder from 1 or more valves---though that would likely be the problem if the cylinder bore is not scored. If the cylinder is really badly worn, the piston can "slap" the sides of the cylinder and that may come back as an audible noise, but I've only heard that happen in old 2-stroke motorcycle engines... I think you'd be having some pretty seriously high oil consumption to get piston slapping noise in a relatively modern car engine. The ticking could be something as simple as a brake pad on that side of the car... or it could be related. Hard to know.

I think it shows great character to not want to off-load the issue onto an unsuspecting stranger.

deilenberger

Scoot (and LuckyKey) - in this case - a leak-down test done by someone knowledgeable might be valuable.

If they are good at it - they will listen at the oil filler to see if leaking is past the rings (you'll hear it), and they'll listen at the intake with the throttle fully open to determine if leakage is past the valves (again - you'll hear it.)

From reading posts on the subject - the boroscope may not reveal much at all if the damage isn't severe - the scoring takes place below the top of the piston even when the piston is at bottom-dead-center. I guess when the damage is really bad - the scoring starts working up the cylinder wall and may be visible with the boroscope.

At least that's the story going around.