How Does Variocam Work

[lmurthwaite]

And do I have it? I have a 1998 3.4 C2 tip. I have posted about this before but on closer inspection have found that when I give my car a hard drive the engine knocks from what appears to be the cam end of either side of the engine. At first I thought it was just the left bank but I heard it pretty clear from the right after a particularly stressful drive home from work which resulted in a heavy right foot. It's only after sustained hard driving that it appears and after a while it settles down and becomes quiet again when driving normally or left switched off for a bit. The drive home from work is just the A2 so no lateral forces come into play with twisty roads or anything. It's definitely a metallic sound like a badly adjusted tappet or worn cam but as the noise disappears after it's calmed down it can't be anything that is permanently worn or damaged.

Becoming increasingly concerned but would like suggestions so that I am armed with some info before I garage the car.

Any ideas?

[x5rap]

And do I have it? I have a 1998 3.4 C2 tip. I have posted about this before but on closer inspection have found that when I give my car a hard drive the engine knocks from what appears to be the cam end of either side of the engine. At first I thought it was just the left bank but I heard it pretty clear from the right after a particularly stressful drive home from work which resulted in a heavy right foot. It's only after sustained hard driving that it appears and after a while it settles down and becomes quiet again when driving normally or left switched off for a bit. The drive home from work is just the A2 so no lateral forces come into play with twisty roads or anything. It's definitely a metallic sound like a badly adjusted tappet or worn cam but as the noise disappears after it's calmed down it can't be anything that is permanently worn or damaged.

Becoming increasingly concerned but would like suggestions so that I am armed with some info before I garage the car.

Any ideas?

From Wikipedia - and we all know that if it's on Wikipedia...it must be true - Right?:

VarioCam is an automobile variable valve timing technology developed by Porsche. VarioCam varies the timing of the intake valves by adjusting the tension on the timing chain connecting the intake and exhaust camshafts. VarioCam was first used on the 1992 3.0 L engine in the Porsche 968.

Porsche's more recent VarioCam Plus combines variable valve timing with two-stage lift on the intake side. The two-stage valve-lift function is performed by electro-hydraulically operated switchable tappets. Each of these 12 tappets consists of concentric lifters which can be locked together by means of a pin. The inner lifter is actuated by a small cam lobe, while the outer ring element is moved by a pair of larger-profile lobes. The timing of each valve is seamlessly adjusted by means of an electro-hydraulically operated rotary vane adjuster at the head of each intake camshaft.

Valve timing and the valve profile are continuously altered according to conditions and engine load. For improved responsiveness on cold starts, VarioCam Plus raises the amount of lift and retards valve timing. At medium revs with minimal loads, the valve lift is lowered and timing advanced to help minimize fuel consumption and emissions. For maximum power and torque, the lift is raised and the timing is advanced. This system debuted on the 1999 Porsche 996 Turbo.

[Loren]

LOL - there was no MY99 Porsche 996 Turbo - the 996 TT was not introduced until MY01.

Let's try this technical explanation from Porsche's MY1999 Service Information Technical Introduction:

"VarioCam

VarioCam, the adjustment of the intake camshafts at engine speeds of approx. 1,300 rpm* and 5,920 rpm, produces a major part of the engine output, the engine torque as well as the good exhaust values at idling speed. Engine speeds below 1,300 rpm produce a slight overlap in the valve stroke curves for the intake valves in relation to the exhaust valves.

This particularly affects low proportions of hydrocarbons (HC proportions) in the exhaust gas before the catalytic converters. If the engine exceeds the 1,300 rpm mark *, the intake camshafts are adjusted by 12.5° (by 25° if measured a the crankshaft).

Adjustment of the camshafts to produce a greater overlapping of the valve stroke curves for the intake and exhaust valves results in improved cylinder charging and thus an increase in engine torque. In the case of engine speeds above 5,920 rpm, the intake camshafts are returned to the basic control times (as for engine idling speed). If the intake valve closes later, additional amounts of intake air can be drawn in. This produces a recharging effect since the flow of air is not interrupted. This also results in improved charging of the cylinders and an increase in performance.

* The value 1,300 rpm increases to 1,480 rpm with engine oil temperatures of approx. 133°C."

"VarioCam

To increase the torque and to improve cylinder charging, the engine has two VarioCam actuators which are installed in the chain tensioners of the camshafts. The two actuators are operated by electromagnetic valves activated by the DME control unit.

Functioning

When the ignition is switched on, the electromagnetic valves of the camshaft adjusters are supplied with positive potential. If the engine is started, the control unit applies ground to terminal 25 (camshaft adjuster for cylinder line 4 - 6) and to terminal 52 (camshaft adjuster for cylinder line 1 - 3) if the following conditions are fulfilled (VarioCam activated);

1 - Engine oil temperature between -3°C and 133°C

2 - Engine speed > 1,300 rpm

3 - Throttle opening > 5%

or

1 - Engine oil temperature > 133°C

2 - Engine speed > 1,480 rpm

3 - Throttle opening > 3.9%

The ground potential is deactivated by the DME control unit (VarioCam deactivated) if:

Engine speed > 5,120 rpm"

[RF5BPilot]

Given the explanation above, what causes the "bump" in power at about 3,000 rpm for the 3.6 engine? (Traditionally people have said it was the variocam -- but the rpm's listed in Loren's post suggest otherwise.)

[Loren]

Given the explanation above, what causes the "bump" in power at about 3,000 rpm for the 3.6 engine? (Traditionally people have said it was the variocam -- but the rpm's listed in Loren's post suggest otherwise.)

VarioCam Plus is quite different

As a Contributing Member you can read the 4 page write up in the MY2002 Technical Information Book.

[lmurthwaite]

Given the explanation above, what causes the "bump" in power at about 3,000 rpm for the 3.6 engine? (Traditionally people have said it was the variocam -- but the rpm's listed in Loren's post suggest otherwise.)

VarioCam Plus is quite different

As a Contributing Member you can read the 4 page write up in the MY2002 Technical Information Book.

Looks like I might have something a bit deeper going wrong. Sat listening to the car tick over last night and it started knocking for no reason and then stopped again after a while. Think there maybe some open heart surgery required in the new year.

Oh woe is me.

[c70Pete]

Given the explanation above, what causes the "bump" in power at about 3,000 rpm for the 3.6 engine? (Traditionally people have said it was the variocam -- but the rpm's listed in Loren's post suggest otherwise.)

VarioCam Plus is quite different

As a Contributing Member you can read the 4 page write up in the MY2002 Technical Information Book.

Looks like I might have something a bit deeper going wrong. Sat listening to the car tick over last night and it started knocking for no reason and then stopped again after a while. Think there maybe some open heart surgery required in the new year.

Oh woe is me.

I have the same sound you have... coming out of the right rear of my car.... took it to porsche... scored cylinder #6... the explanation from a tech is probably the bearings are worn out and it causes the knocking at low rpm.... when I rev my engine past 4000 rpm the knocking disappears...

does your knocking disappear over 4000 rpm? I can't say for sure what your issue is but are you burning a lot of oil as well?

[lmurthwaite]

Given the explanation above, what causes the "bump" in power at about 3,000 rpm for the 3.6 engine? (Traditionally people have said it was the variocam -- but the rpm's listed in Loren's post suggest otherwise.)

VarioCam Plus is quite different

As a Contributing Member you can read the 4 page write up in the MY2002 Technical Information Book.

Looks like I might have something a bit deeper going wrong. Sat listening to the car tick over last night and it started knocking for no reason and then stopped again after a while. Think there maybe some open heart surgery required in the new year.

Oh woe is me.

I have the same sound you have... coming out of the right rear of my car.... took it to porsche... scored cylinder #6... the explanation from a tech is probably the bearings are worn out and it causes the knocking at low rpm.... when I rev my engine past 4000 rpm the knocking disappears...

does your knocking disappear over 4000 rpm? I can't say for sure what your issue is but are you burning a lot of oil as well?

Not burning any oil I and the knoking seems to disappear whenever it wants to no matter what rev range I use. It can run fine, start knocking from either the left or right bank and then stop after I switch the engine off and restart or it will just stop on it's own. It drives well too, even when it is knocking. It needs to be garaged I think I just need to get a ballpark on what it could be as the last place I took it to said is what normal. I don't buy that though. Nothing that knocks is normal as something is wearing out due to it !

[1schoir]

Given the explanation above, what causes the "bump" in power at about 3,000 rpm for the 3.6 engine? (Traditionally people have said it was the variocam -- but the rpm's listed in Loren's post suggest otherwise.)

VarioCam Plus is quite different

As a Contributing Member you can read the 4 page write up in the MY2002 Technical Information Book.

Loren:

How is the MY2002 Technical Information Book accessed?

Regards, Maurice.

[Loren]

Given the explanation above, what causes the "bump" in power at about 3,000 rpm for the 3.6 engine? (Traditionally people have said it was the variocam -- but the rpm's listed in Loren's post suggest otherwise.)

VarioCam Plus is quite different

As a Contributing Member you can read the 4 page write up in the MY2002 Technical Information Book.

Loren:

How is the MY2002 Technical Information Book accessed?

Regards, Maurice.

Go to Downloads > Contributing Members Only > Service Information Books

[Giova2k11]

Sorry to bump such an old thread; I'm working on an university project and I need to know more about the VarioCam system, particularly how the electromagnetic valve gets the oil that moves the piston in the camshaft chain tensioner; my guess is an oil passage in the block and head, which gets to the valve from below, but I'm not sure about that; also, I'd like to know how the oil is then drained from the chain tensioner when the top slider goes back to its original position. Does this happen only through the two little holes in the top slider?

If I'm not mistaken, when the system activates over 1300 rpm the intake valves timing is advanced, then it goes back to the original timing when rpms go over 5100. Is that right?

[Loren]

Sorry to bump such an old thread; I'm working on an university project and I need to know more about the VarioCam system, particularly how the electromagnetic valve gets the oil that moves the piston in the camshaft chain tensioner; my guess is an oil passage in the block and head, which gets to the valve from below, but I'm not sure about that; also, I'd like to know how the oil is then drained from the chain tensioner when the top slider goes back to its original position. Does this happen only through the two little holes in the top slider?

If I'm not mistaken, when the system activates over 1300 rpm the intake valves timing is advanced, then it goes back to the original timing when rpms go over 5100. Is that right?

Here is the description from the Porsche Technical Book for the 3.4 liter engine that used VariCam

"1536 • VarioCam

VarioCam, the adjustment of the intake camshafts at engine speeds of approx. 1,300 rpm* and 5,920 rpm, produces a major part of the engine output, the engine torque as well as the good exhaust values at idling speed. Engine speeds below 1,300 rpm produce a slight overlap in the valve stroke curves for the intake valves in relation to the exhaust valves.

This particularly affects low proportions of hydrocarbons (HC proportions) in the exhaust gas before the catalytic converters. If the engine exceeds the 1,300 rpm mark *, the intake

camshafts are adjusted by 12.5° (by 25° if measured a the crankshaft).

Adjustment of the camshafts to produce a greater overlapping of the valve stroke curves for the intake and exhaust valves results in improved cylinder charging and thus an increase in engine torque. In the case of engine speeds above 5,920 rpm, the intake camshafts are returned to the basic control times (as for engine idling speed). If the intake valve closes later, additional amounts of intake air can be drawn in. This produces a recharging effect since the flow of air is not interrupted. This also results in improved charging of the cylinders and an increase in performance.

* The value 1,300 rpm increases to 1,480 rpm with engine oil temperatures of approx. 133°C."

The 3.6 liter engine used VarioCam Plus.

"1584 Variable camshaft timing with valve stroke control (VarioCam Plus) The demands placed on the design of an engine, i.e. increased performance, improved driving comfort, observance of legal emission limits and reduced fuel consumption, result in contradictory construction criteria.

The idea behind the development of the VarioCam Plus was to create a variable engine which can be optimised both for maximum performance and for frequent use in urban traffic or on main roads.

A system to adjust the intake camshaft to vary the opening and closing time combined with a valve stroke adjustment system is the solution to this problem."

Hope this helps some

[Giova2k11]

Thanks, it does clarify some of my doubts :)

[logray]

Also have a look at the images in the first post in the following thread...

http://forums.rennlist.com/rennforums/996-forum/557016-how-variocam-and-variocamplus-works-a-primer.html

[Giova2k11]

Thanks, that is even more helpful, now I've perfectly understood how the system works. :thumbup: :thumbup:

[Claudio Vtr]

alguém pode me dar uma dica sobre o codes fault P0082 numa porsche cayenne turbo 2011 qual a solução?

[Loren]

alguém pode me dar uma dica sobre o codes fault P0082 numa porsche cayenne turbo 2011 qual a solução?

 

Please post in English if possible.

[JFP in PA]

 

alguém pode me dar uma dica sobre o codes fault P0082 numa porsche cayenne turbo 2011 qual a solução?

 

Please post in English if possible.

 

 

Try this: "can someone give me a tip on the fault codes P0082 porsche cayenne turbo 2011 in which the solution?"

[Loren]

 

 

alguém pode me dar uma dica sobre o codes fault P0082 numa porsche cayenne turbo 2011 qual a solução?

 

Please post in English if possible.

 

 

Try this: "can someone give me a tip on the fault codes P0082 porsche cayenne turbo 2011 in which the solution?"

 

 

Fault P0082 - Final stage - valve lift control, bank XFinal stage - valve lift control, bank X

 

Possible fault causes:

 

• Loose contact or corrosion on connectors or lines

• Short circuit to B+/ground/between lines or open circuit in the lines

• Solenoid hydraulic valve VTC bank X faulty