variocam stutter?

[Stevenorcal]

I have read several posts regarding a hesitation in 996 turbo and replys have included "varicam" as the cause. I have similar issue i think, replaced plugs, tested or had "reviewed" coils etc. All is fine. What is Varicam doing that makes this issue happen and why? I am still trying to decide if this is something I want to pursue with Dealer or elsewhere.

thank you

[JFP in PA]

The VarioCam is altering the relative positions of the intake and exhaust cam lobe centerlines using combination solenoid and oil hydraulics; in doing so, in can significantly increase both the drivability and power output band of the engine. There have been several postings of excellent "how does it work" profiles, so do a search if you would like to learn more about how it functions mechanically. The major difference between the early VarioCam and the later VarioCam Plus is that the later system can incrementally alter the centerline differences over a fixed range, while the earlier system switched between only two settings.

The best way to see how the system is working is by using either a PIWIS or the Durametric software system, which can give you the actual cam angle changes in real time.

Edited November 13, 2010 by JFP in PA

[jpflip]

I would be easy to test if you got access to Durametric.

This software got a "drive link" function that aloud you to test both banks of the vario cam system. There is a total of 4 solenoid that control oil pressure to the system. Two per banks. two for the valve opening, 3mm or 11 mm. The other two are for the cam advance 0 to 40 degrees. With Durametric you can simulate a signal to one of those solenoid and if the engine suddenly hesitate after triggering the function you know the signal is functioning. There is another item you can look at is the solenoid bracket. Porsche came out with a TSB to inspect the solenoid bracket. This solenoid is located on each bank about the middle of the head and are used for valve opening. If the bracket is broken the solenoid come out of his seat and the oil pressure is not going to the system anymore.

Edited November 13, 2010 by jpflip

[Stevenorcal]

thank you both for your imput. I have just ordered a durametric and when it gets here i will run through it. I did read posts regarding function and if it is dislodged is it hurting motor or making a odd noise. seems simple enough to remove and replace, i think mine might be broken and dont want to hurt motor if i continue to drive.

thank you again.

[PAULUNM]

Steve, any update?