Hello and thank you for reading my first post. I am a new member and I apologize if some of my knowledge is limited as this is my first Porsche.

My problem is with my 2002 Porsche C4S 6 speed that I recently bought back in March of this year. I bought the car as it came out of 6 months of winter storage. It had and still has 67,000 KM on it.

After I bought it, I went away for a couple months and left it in my garage for storage. I came back in May and started the engine and let it idle for about 10 minutes since it had been sitting so long. I then took it up and down the street never exceeding 40km/h or pushing it beyond 4000RPM. The engine fully warmed up and after about 25 minutes into the driving on the street I was about to park back in my driveway when the car stalled out. I restarted and the engine ran really rough (like a tractor) and the idle was frantic. I could barely keep it running long enough to park it and when I blipped the throttle the ticking pitch increased in sound. At the time when I was driving there was a sudden torrential downpour of rain. I could only think the water messed up a coil pack and caused a misfire. I was going away for a couple months again and parked the car back in the garage.

Now, months later, I have returned and when I started the car it sounded the same, but idled more smoothly and the check engine light was still on telling me to seek a service shop. I bought a Durametric tool and received the following codes:
PO300 - Porsche Code 507 - Misfire Detected
PO301 - Porsche Code 508 - Misfire Cylinder #1
PO304 - Porsche Code 511 - Misfire Cylinder #4
I assumed it was plugs/coils and advised the mechanic to buy all 6 brand new plugs and coils since they had never been replaced yet. After installation the mechanic started the engine and received misfire codes for cylinders #1, 2, and 3 now??? Then a compression test was performed and cylinders #2, 3, 4, 5, 6 all showed 220 PSI, EXCEPT cylinder #1 ... this cylinder showed ZERO compression. Also, I don't understand why cylinders #1, 2, and 3 would now show misfire?

The mechanic thinks there are several scenarios:
1. A valve is broken or faulty - could be contained and replaced OR it could have broke and fell into the cylinder causing damage unknown without pulling the motor out and removing the head to determine if the engine can be repaired or needs replacing
2. The valve is stuck open because it sat so long and oil bled out overtime or the valve is seized open.
3. Cylinders 1, 2, and 3 show misfire because of vibration from cylinder #1, even though cylinders 2 and 3 are actually fine?

From what I read on these forums and others, there are things like the hydraulic valve solenoid or actuator? I really don't know what is going on. In the end, I just invested my savings into my dream car of owning a Porsche and I have become so discouraged before I even got to drive it. I dread going to the Porsche dealer because they tend to replace rather than diagnose from what others have said.

Has anyone had this problem with their Porsche or any insight (positive or negative) into this problem? If anyone is local to the Burlington area that would be a plus too. Please advise if you have any further ideas of what could really be going on.
Tomorrow the mechanic is going to remove the valve cover and perform a leak down test. I will keep you posted ....

THANK YOU!

 

The cost of a remanufactured engine scares me! I hope this is not my case. I went to the shop today and my mechanic showed me (with the exhaust manifold off) cyclinder #1's valves were bent and not seating properly. The piston would stroke and "slap" the valves closed and now has damage to it's surface, but the mechanic says this should not affect it terribly. In the end the engine must be removed to take off the cyclinder head and he is advising re-machining of the head and replace all 12 valves on the one side of the engine. Until the head is off, further damage is unknown. He thinks because it sat so long the oil was gone in the head and the valve guide seized ???

I'm at a loss, has anyone experienced this problem or done the rebuild to find success?

 

After removing the engine from the car over the weekend I could see cylinders 1, 2 and 3 had their pistons slap all the valves on the exhaust side. I assume since I never ran it long it did not do extensive piston damage. I am now replacing all valves and have the guides and head sent to a shop for x-ray to identify stress fractures before installing again. In the end, the hope is there is no further problems and the engine will run fine.

Now, the reason WHY it may have occurred is just an idea. The only plausible explanation is the car had been sitting so long and the oil bled out of all the valves and the timing chain tensioner. Once I ran the engine the hydraulic tensioner was not applying pressure on the chain and as mentioned in my earlier post I drove the car slow and under 3-4000 RPM. Perhaps once it revved higher the tensioner did not function and the chain skipped a tooth = misfire = piston slaps valves =

In the end, I think this is what caused my problem and I hope the rest of the engine is okay after this repair ... I really don't want to buy a new motor.

Moral of the story = drive your Porsche and don't let it sit. I plan on starting the engine every 3 days through the winter storage, rather than let it sit and miss out driving it in the summer, as happened this year.

 

Well, for those who are interested I will post my final message regarding this matter. The bent valves were replaced along side all the guides. The head was resurfaced and the car was run for several hours at idle. Now, after a few oil changes there are no more contaminants and the car is back on the road running flawlessly

The total job cost just over just under $5000 for the parts and labour. For anyone in the Golden Horseshoe area requiring an honest Porsche mechanic for major tear down or regular service I would recommend the place I went to. The owner's name is Amnon and the business name is "Raz Automotive Services". You can contact him at (905) 561-1555 or the address is 2837 King Street East in Hamilton, Ontario.

The stealership would have wanted to replace my engine, but Amnon was able to properly diagnose and repair the problem. The car runs great and has no lights coming on the instrument panel any time now. All in all, it was a costly mistake, but I will not le tthe car sit parked so long when in storage now.