2006-2008 Cayman S Engine Health- Durametric and Variocam+

My 2007 Cayman S engine has a variable valve timing (VVT) system that Porsche calls Variocam+. The concept of variable valve timing has been around for a long time before the Cayman and probably, if one were to research it, some version of variable valve timing was probably invented during the earliest days of automotive design. Regardless, VVT allows the timing of certain valve opening and closing events to be optimized over the entire operating range of the engine. There are multiple benefits. The engine design can obtain a flatter “torque curve” so the engine pulls strongly and consistently from low to high revs. The emissions profile of the engine can be optimized. Fuel consumption is improved. For more information, I have posted some text (at the end of this article) from a Porsche document that I have that gives the Porsche perspective regarding how the system works. FYI for other articles in this series, Search on “Durametric” and also “Engine Health” on my website.

The Porsche Variocam+ system adjusts the timing only on the intake valves. The camshafts for the intake valves (2 valves per cylinder, 2 camshafts per bank of 3 cylinders) can be rotated on their axis by a hydraulically actuated adjuster. This effectively adjusts their position with respect to the crankshaft and thus with respect to the position of the piston in the cylinder. You will commonly hear that the timing is “advanced”. This means the camshaft is rotated so that the intake valves open further in advance of the position of the rising piston. Of course, this also means that the intake valve closes sooner by the same amount but the net effect is favorable. Test engines are run at many positions of rpm, load, etc. with various amounts of advance, until the best advance value is obtained for all operating conditions. This profile is stored in the Engine Control Unit (ECU) and used actively as you are driving your car to continuously set your intake camshaft to it’s optimum position. This advance is the subject of this Engine Health article. BTW don’t get this intake camshaft timing “advance” mixed up with spark advance. The timing of when the spark plug fires on the Cayman engine is also adjustable by the ECU but this is not the subject of this article.

Before we get into the signs of a healthy advance profile, we need to talk about the “+” part of Variocam+. For Porsche, Variocam was a designation for intake valve timing that was introduced back in the 80’s. In the “oughts”, a “+” was added to Variocam. In the Porsche engine, the “+” system is entirely different concept. The “+” system serves to adjust the total distance that each intake valve opens. This is a clever process and best described by others but in essence there is a “low lift” position and a “high lift” position. I have linked a youtube video below that describes the basic operation. Unfortunately, at this time I have not been able to find any Durametric Actual Values that would indicate that this system is working at all, much less what healthy versus unhealthy looks like. If anyone knows, please let me know. There is a Durametric function to “actuate” the variable valve lift but I have been loath to try that until I better understand any restrictions or cautions.

Getting back to intake camshaft advance, there are two Durametric Actual Values that can pretty quickly give you an indication that your engine is healthy. You basically want to track Nominal Camshaft Angle and Actual Camshaft Angle. As the names would suggest, the first parameter is the requested amount of advance, which is determined by the operating conditions and the table of stored values in the ECU. The second parameter is the actual advance value, as determined by the Camshaft Position Sensor. These two parameters are reported for both Banks 1 and 2. Using the process discussed in a previous article, you will have to go for a road test and collect data. I would also suggest that you collect engine rpm and load. Whether you are sneaking a peak at your data in real time or are looking at your Excel files later, you should basically see that the two values track each other very closely, within a degree or so. This may not be the case during shifting, etc. but under most normal driving conditions, they will be very close together. Also, on my car, 25 degrees of advance seems to be a typical value. I believe 40 degrees is the maximum the system can obtain. I cannot speak to the question of “how much deviation is bad?” There was a fellow on Rennlist who was getting something on the order of 20 degrees of deviation. He had a problem with a collapsed oil filter.

I’m not here to troubleshoot but as noted above there is a hydraulic adjuster that causes the advance. It is driven by engine oil pressure. It is activated by a solenoid that sticks out of the side of your valve cover. There is a similar solenoid for the variable valve lift. Mechanically that is about it. Electrically, the solenoids are activated through plug connectors that lead to the ECU. The Camshaft Position Sensor is located at the ends of the two camshafts and has its own wiring connector, leading back to the ECU. So if the system isn’t working correctly, there are a host of things to track down!

How the Variocam+ works, courtesy of Porsche.

The following videos show locations of a number of components on the engine from my 2007 Cayman S, including the Camshaft Position Sensor and the Solenoid. I apologize but in the video I’m pretty sure my commentary has the positions of the two solenoids backwards. It is very frustrating in that the Porsche PET basically describes them identically as Throttle Control Elements. Items 39 and 45 on Illustration 103-000. But having torn my engine down completely, I now know that the solenoid nearest the end of the valve cover controls the variable intake valve timing and thus the other one controls the variable valve lift.

Here are some text excerpts from Porsche After Sales documents, which provide some additional details regarding the Variocam+. From an engine health standpoint, this is just good background information. Not reprinted here but I also gather that if “implausible signals” are obtained from the solenoids (such as a short or open circuit) this will be identified by the ECU and set some level of warning or error messages. I do not know exactly how these messages would be manifested i.e. dashboard, OBD, etc. Anyway, here is some good stuff to read if you like. BTW, the Porsche Part Number for the Technic document this came from is PNA 987 021 07. It is a valid part number but a call to my dealer indicated that it has no known current availability. Your results may vary.

Activation of VarioCam Plus

The VarioCam Plus camshaft adjustment system which is familiar from the 911 Carrera is also employed on the Cayman S. The DME control unit controls infinite camshaft adjustment and valve lift of the inlet camshafts. The requirements imposed on engine design with regard to high performance combined with good driving comfort, compliance with emission regulations and reduced fuel consumption lead to conflicting objectives in developing engines. The idea of creating a variable engine spurred the development of VarioCam Plus (premiered on the 911 Turbo 996). Such an engine is intended to provide peak performance in terms of torque and power output while also offering optimized emissions and fuel consumption in frequent use in stop and go traffic or on country roads. VarioCam Plus features vane adjuster and switchable hydraulic tappet control elements for infinite adjustment of the timing of the intake valves and switching the maximum valve lift of the intake valves between 3.6 mm and 11.0 mm on the basis of a map. The infinite vane adjuster, which is familiar from the 911 Carrera and Boxster, has an adjustment range of 40°.

The cylinder head and the camshaft timing system have been adopted from the 911 Carrera (997) for the purposes of implementing VarioCam Plus. The cylinder head consists of three parts – cylinder head base, flat-base tappet guide and cylinder head cover. Oil supply to the switch￾able hydraulic flat-base tappets is effected via integrated oil.