Macster

Have you had a tech drive the car, experience the car and the engine's behavior? What does he have to say?

You can certainly have the intake valves inspected for build up on their backs. Any build up at this location will interfere with air flow into the chamber and this will almost certainly affect combustion and not for the better.

If you suspect intake valve deposits or dirty fuel injectors ( they get "dirty" from the fuel drying on them after the engine is shut off -- I might add that normal driving should remove these deposits but often the car doesn't get driven enough and over time the build up increases ) a bottle or two of Techron used according to directions can be of some value.

If the engine perks up you guessed right.

If if doesn't… there is something else going on.

However, in the case of your car with no CEL, no pending error codes, readiness monitors being set to complete -- you'll have to have an OBD2 scan tool to confirm these -- I'd say deposits are high on the list of possible causes.

More than once a customer has come in with similar symptoms with his car and the techs tell me the problem is the car just needs to be driven more, and harder. By harder that does not mean the owner should take up driving the car like he stole it but just use a bit more throttle.

(I recall one owner coming in and getting the "standard" lecture on how to drive his car and he nodded and listened and claimed he understood. Then he got in his car and drove away. The SM and I watched and in no time the owner had upshifted the transmission to 4th gear while he was still in the parking lot. The SM and I turned towards each other as one and smiled.)

slicky rick

Supports were changed because the dealer said it could have been the cause of the vibration lumpy idle. No question the vibration and lumpy idle was there. Idle smoothened out by a large extent when supports were changed. You feel it right when you start the engine. Now vibration has largely been fixed but lumpiness still there, meaning that feel of a slight misfire overy so often. Car gets driven so i might be more leaning to the type of fuel we have. At least once a month car gets 100km runs with 180kph blasts on highway. 3 weeks ago it came from a good mountain run, that was around 250kms, lots of shifting and 80 to 120kph runs on the mountain and e usual 160 to 180 kph highway runs with a few occasional bursts to 210.
Techron is now in the fuel and i have consumed 1/4 th tank. I will try to do two doses before changing oil. The car also does short 3 km runs but i try to get the oil up to op temp as much as i can by driving around some more before parking.
I do notice though that idle sometimes gets better. My diagnose is carbon or a slightly leaking spark plug. After techron, if there are no improvemrnts, i will change plugs.

slicky rick

By the way tech and after sales head drove car and both said it drove a lot better than most of the cars of the type we had here. They were both, however, trying to skirt the lumpi idle issue saying, hmmmm normal but with perplexed look.
Fuel issue causing carbon deposits and or slight leaking spark plug... We will find out.

slicky rick

Some more sharing, before dealer replaced mounts they took a video of a glass of water placed securely on the dashboard of the car. This video was sent to porsche before the mounts were approved for replacement. Great way to check vibration yes? Before our sharp brothers comment, the car running on idle mode...

millertimefl

UPDATE: rick, got car back and all is fixed!! I had your similar lumpy issue and I had a very messy idle...it was all over the place. My issue was only when car was cold before it got to full temp then it seemed to smooth out. Dealer found a few "bank 1 camshaft low readings" codes (like p0016). They replaced one of the Variocam solenoids and it fixed my problem! Car is super smooth and drives like new. Seems the oil driven solenoid was stuck or sticking when oil was cold. Fix was around $450 parts and labor. Props to Bill at Burt Smith for accurately diagnosing the issue first time. My car is 2010 C4S. Hope this helps...

slicky rick

Thanks for sharing bro. I will try to tell my dealer to try and check.

slicky rick

Went back to dealer and has the car checked again. No faults, no misfire in any of the cylinders, maf readings all within range. Fuel pressure also within range. Lets see what else did we look at.....oil pressure in the banks also within limits. But when you sit down everyone acknowledges that there is a miss like vibration felt thorugh the seat....guess what i did....i changed oil, since it was due already. The oil looked very dirty, it was almost black...no metal shaving no particles in the oil...but after changing, all seemed to be well again....still have to run a distance before concluding...just sharing to our brothers.

neanicu

Changing oil has nothing to do with the car running better,it's just a mind exercise.
Although it might be too late now,next time for your piece of mind get an oil sample and send it to Blackstone to have it analyzed. It will tell you if there's accelerated wear in your engine.

slicky rick

Hi nea, yes you might be right. But at least i feel better. But like i said too early to conclude. I did however notice dark oil....maybe due to the 2 doses of techron i did before changing. Only analysis i did of the oil was look at it and see if there were deposits on the filter or the drain pans i used. Fortunately i did not see any. Filter was clean of any mettalic particles, at least to the naked eye. Next i will try to change plugs and see. Dealer was actually suggesting to replace the intank pump hinting it could be partially blocked, even if fuel pressure after hpfp was normal.

slicky rick

nea is right! no change still there....spark plugs are next this weekend. maybe that will produce better results. dealer dont know what to do anymore and resorting to asking me to replace parts that are not covered by warranty....so they say.

neanicu

Sorry to hear Rick!

Reading back thru this thread I still suspect a vacuum leak. Have them pressure test the intake. I haven't seen this posted that it's been done. While they're at it,they could probably run a leak down test and a compression test,just to see if one of the cylinders is not putting out the same power as the others.
Either of these tests my reveal a problem that the PCM couldn't pick up.

Also,I would've suggested the Variocam annoyance(for the lack of a better word),but that manifest while driving at low RPM.



Nick.

mdrums

Rick, I've told you before ....sell this car off...geez my friend you have a new problem with it like every week. No way I could ever put up with these amount of issues. Hope it all works out for you.

slicky rick

ok my brothers. i dont know if i could say hahahahaha but today i i operated on my car.. i did the spark plug change and together with it i change the exhaust with a gundo hack set of mufflers. let me just initially say that i think it was simply the spark plugs! i think i now know why there is a 4 year replacement routine by porsche on these items and it is not just to keep them from siezing in the holes.
mike, i am now a happy camper. this is what its all about my brother. i feel that i have fixed this issue and i did it by myself with the help of all here. So much better than spending a heap with the dealer and not even sure if they can fix. let me run it some more but i can say that it runs like its suppose to now.

mdrums

Yea!!! Case closed...next? LOL....have a great weekend Rick