Stuck cam adjusters.
 

This seems to be a common problem.

Symptoms are poor/lumpy idle, bad off idle performance, overly large rpm drop when coming to a stop, sometimes resulting in a stall.

From research, both online and at a couple of shops, the cause seems to be cam adjusters that are either stuck or slow to react, which causes the cams to be out of time, trying to idle with cams that are set to be high performance at 5k rpm.

The adjusters themselves are a solenoid that works via a spring and an electromagnet. The electromagnet moves the solenoid as needed by the computer, the spring pushes it back. It seems to work on about 2-5v.

The adjusters have a stainless mesh screen that some people believe have sections that are tighter than the oil filter. Stuff get stuck in these screens, and/or the adjuster gets sludged up from oil changes that are not frequent enough and it does not react as it is supposed to.

the solution given to me by a couple of shops was to replace the adjusters. On the Cayenne this is somewhere between $1000-2000 from what I hear.

The VW W8 guys had a bigger problem. Their adjusters were on the back of the engine vs. the front, meaning an entire engine drop and a bunch of disassembly for replacement. This was said to run $8k+.

The solution they came up with was to shock the adjusters with higher than normal voltage to get them to actuate to full extension forward and back several times. This has been tried up to 12v, I use a 9.6v drill battery.

There is a local VW shop that charges $250 to "massage" the adjusters and get them working right again. I heard about this from another enthusiast and decided to research it.

Came upon this thread:

Found: Camshaft Adjuster Fix!!! - The W8 forum - Page 1

This gave me enough detail to be willing to try it.

So here is where they are, it's pretty simple.

Take off the cover to the right of the oil filter (and matching one on the other side):
http://forums.pelicanparts.com/uploa...1384833414.jpg

Pull the plug underneath by popping off the retaining spring:

http://forums.pelicanparts.com/uploa...1384833470.jpg


And then this is my rig for cycling the adjuster, just a drill battery with a couple leads. I do it both directions since I don't know a great way to tell positive from negative, and it shouldn't hurt it since it's a pretty simple device and will just push one way or the other:

http://forums.pelicanparts.com/uploa...1384833553.jpg

As always, at your own risk, your mileage may vary, etc. etc.

With that said this has made a big improvement in the idle on ours, though it's still a little grumpy now and then.

We've been changing the oil a lot more often than suggested by the manual since that's known to make this issue worse.

Hopefully between the two it'll clear up eventually.

Interesting. Have you received any CEL's before or after?

Nope, no lights before or after. Since it's not really emissions related, it doesn't throw the light. Though conversely, when it's happened early to people I've heard they argued it under the longer term emissions warranty.

Sometimes there will be a cam deviation code if you hook a reader up to it, but they do that for a lot of reasons apparently.

Rob, I hope this works for you.

I was one of the unfortunate souls with a W8 Passat that had this problem, in fact every W8 Passat has this problem or will.

My adjusters were replaced under warranty at 46k, the bill I saw to VW was 10k!!!

They failed again at 120k, and like you I came across this write up.

So with the help of my mechanic we zapped the adjusters and bingo, it cleared the codes and reset the adjusters. At this point I thought it might be a good idea to sell the car, but I delayed because I really did love my Passat wagon and I hoped with this fix all would be good.

It stayed fixed for around 1.5k! Again we tried to zap, but with no luck. So we waited overnight and the next morning we zapped again. Finally they reset and I promptly traded the car to a VW dealership - they didn't even take the car for a test drive or read the codes, more fool to them I thought.

With VW, this was covered under the emissions warranty. So you might want to double check that.

I hope this is a solution for you, I hate to be a downer, but I wouldn't bank on it!!


Cheers

Matt

I tried this on mine over the last couple days. Before and after an oil change.
On the drivers bank (left) I get a solid sound of something moving as I cycle power to the terminals.
On the passenger (right) I get a light click. Definitely a different sound.
The only CEL I have gotten in 7K miles is from a loose gas cap.

It will be after the first of the year before I can spring for Durametric software. Anyone know if it will measure the cam advance? and, Does it use the voltage to say what the advance would be if the solenoid is working?
Ideas? other checks to compare to?
Thanks

Matt - good to know your experience. Luckily the Cayenne engine is backwards, so even if they end up being replaced they are far easier to get to. I'll look into the emissions warranty, it's a stretch, but maybe.

Lance - It's the passenger side on ours that's sticky also. I know both from a shop's software (though I can't remember if it was a Durametric or something else), and from the difference in feel. I think there also might have been a code that didn't throw a light when I pulled regular OBD codes that implied passenger.

I'm still going to try the passenger side with 12v a few more times, have only done it with 9 so far.