Here’s a DIY hack before you go full pro mode: try a smoke test to hunt down that sneaky vacuum leak. You can DIY this with a cigar (no joke) or a smoke machine if you’re fancy. Puff smoke into the vacuum lines and watch for where it seeps out.

That's a really helpful suggestion, and timely too: planning a trip to a cigar shop with a Porsche friend tonight!

BTW, again running smoothly with no codes!

 

I did try the cigar smoke test with no result.
I then consulted a local guy I've been using for jobs I used to employ my lift to accomplish (I have moved and no longer have a two-post lift.) He suggested--no kidding--some Seafoam or equivalent, theorizing poor fuel. I had thought of that but always stick to Shell premium, though that doesn't preclude a contaminated load. He also thought it could be vacuum or the sensor on the way out.
So I'm trying the Seafoam, and it has been smooth, but I'm not counting on that resolving the problem. It's too easy.

 

...and it was.
I've ordered the Valve Lift Controller. The mechanic says that is most likely the problem.
Will update.

 

Oh, these were the codes, per Durametric:
--P1372--Valve Lift Control, Bank 1
--P1362, -63,-61--cylinders 4, 3, 2 out of range (I think; can't read my note)
--P0172--rich, below limit value

 

Waiting to hear after it's installed. Just out of curiosity - have you ever added any oil additive to the engine, if yes, what?

The reason I ask this my mechanic has a real fear of parts like this failing after additives are used. I had used a Lubromoly seal conditioner to try to stop a very tiny leak from the rear seal (it appeared to work) but its certainly possible that a path like these solenoids live in (not really a flow path, more pressure modulator for the cam lift mechanism) might plug up due to an additive.

 

Fear not! I never use that stuff. I developed an aversion, if not an allergy, after the STP era.
I did perform an oil change at the same time I cleaned the MAF sensor, so it does raise the question of which may have smoothed the idle--temporarily, anyway.

 

Fresh oil with fresh detergent might well have cleaned it up. It might be interesting to drive it for a while and see if it reoccurs

 

Update; controller came in--it was wrong. There was an update along the way.
Then my guy got the right one, but it didn't please him, so he got another.
It's still a little lumpy, and he says it shows codes (I have not yet tried Durametric) but no check engine light.
I'm going to drive it and see what develops. I hope nothing terminal.

 

Please do keep us informed!

 

It's now just intermittent.
So, since it may be related to oil flow and possible blockage, I'm going to take a page from my Chevy Silverado playbook.
If you are familiar with the LS in them, the oil pressure switch gets gunked up and fires off the check engine light. I've discovered that Pennzoil, of all oils, somehow cleans it up such that the light goes out for several thousand miles after an oil change. (Don't ask why I haven't just replaced the switch. If you think some of Porsche's connectors drive you mad, imagine one you can't see, and no one can explain how to release.)
So that's the next step. I will update when done.

 

The promised update.
I've had the Pennzoil in there for a few weeks, but really not many miles. The problem isn't cleared, but I have noticed a change, or perhaps just noticed this. It seems the rough idle is only from a cold start, when the pressure is high and temp low. After warmup, I don't feel the vibration. Check light is still on. I haven't cleared it but intend to after the next fill-up.
I'll continue monitoring and report back.

 

Today, it had the usual cold rough idle. Then we took about a 10 mile drive for breakfast. On the way back, I noticed the "check engine" light was out!
I suspect it will reappear on the next restart.
I've researched a little more, and there seems to be an idea there there is some sort of restriction before the valve lift controller that can get blocked.
If anyone else has experienced this, how did you fix it?

 

On the earlier V8 4.5L engines - the Variocam system (just cam timing changes) - where the solenoid fastened into the oil passage, there was a screen in the oil passage on the solenoid input side. The screen didn't come out with the solenoid.

Those were known to get plugged up. The official Porsche fix on them was to remove the screen (and throw it away) then put the solenoid back in place.

Could be? Would need to really study an exploded parts diagram.. or if you can see the passages - a mirror and bright flashlight?

 

Warning light reappeared, then went out again during another drive. The new wrinkle is that after warmup, the idle is smooth. Also, if shut off while rough, it is smooth on the restart.
I've looked at the parts diagram (are they still called "fiche?") and can't locate a screen. Actually, I can't even see the controller. I'm checking with a dealer parts department for verification.
Anyway, the Pennzoil seems to have some effect.

Don, I also have a BMW bike, an 1100R. I miss my R75/5. Are you getting another?
And love your tag line!

 

Anyway, the Pennzoil seems to have some effect.

Don, I also have a BMW bike, an 1100R. I miss my R75/5. Are you getting another?
And love your tag line!

FWIW - I have no idea if the flat-6 engines have the screen or not. It was an issue on the early V8 variocam plus engines. Maybe you can get a photo of the port it screws into in the engine next time you have it out?

And right now - I'm not actively looking for a new bike. I have about 150,000 documented miles on bikes (and about 100,000 non-documented), and only one stupid accident (zero-speed wipeout in sugar sand - causing the motorcycle to fall on my leg - breaking it. I did ride the bike home though from the accident..) I've ridden cross country 4 times, all over eastern Canada and Europe. I've got most of the bucket items behind me. The problem is age - the R1200R was a wonderful bike, but it was getting too tall for me (even with modified suspension - it had me on tip-toes) and too heavy when it started leaning in a parking lot situation. BMW doesn't make lower bikes so they're out of consideration. I've thought about a maxi-scooter (Burgman or similar) I know many older BMW riders who've gotten one and were happy with it - but I'm not in a rush to do it. The convertible satisfies about 70% of my fresh-air obsession. It's the remaining 30% that I sometimes miss a bunch.

 

Idle remains inconsistent. Frustration is setting in and a trip to the dealer may be mandatory. We have no local specialists. I always seem to end up in a specialty desert.

I hear you on the bikes, Don. I think I'm just going to accept that I've had my fun there and subsist on memories. I raced desert, MX, enduros and WERA roadraced. My last physical showed I've lost a few inches which accounts for my stretch to reach the ground---and I did not start at a great height!

 

A dealership parts person confirms there is no screen below the controller to account for a possible blockage.
It seems the problem occurs below a 150 degree oil temp.
Codes now (check engine light is back) are P1361, 1362, 1363, 0133, 0303. 1572, 0455.

 

I had to take the vehicle into a Porsche dealer for another issue. While there, mentioned this problem to the service advisor. He got the head tech who explained I had replaced the wrong solenoid! It is the one at the rear of the cylinder head, not in the head under the cam cover. So, that's on the to-do list. Not looking forward to it as it looks like a tough one to access.
So at least the mystery is solved.

 

That's the one I thought I was referring to... it's what needed replacement on my Cayenne 4.8 Twin Turbo engine, and from talking to the shop that did the work, it's a rather common failure on the H6 engines. They offered me the choice of the Porsche packaged item, or an aftermarket one they'd used with success on H6 engines (apparently the exact same part..) Since the labor was the primary cost on my TT engine (removal of the camshaft driven vacuum pump was needed to access it..) I went with the Porsche one. Rethinking it later - I should probably have gone with the aftermarket one - since they'd be covering the labor if it failed again.

Glad the mystery is solved..

Update - I looked back and found I said "solenoid that controls valve lift on bank 1" - the solenoid that you replaced controls valve timing.. but I should have been clearer - said it was the one on the back of the head.. sorry.

 

Ended up replacing the VLC and all is well.
That is what i should have done intially, but somehow got derailed to the valve timing solenoid.
Expensive lesson.