VarioCam Plus issues revisited

[Cloudsurfer]

I have been having issues with drivability and after diagnosing with the PST, I have a "laggy" valve advance on Bank 1-3, where it would take considerably longer than Bank 4-6 to advance, and while it was "taking it's time" to advance on acceleration the car would cough and sputter. Today i changed the valve phasing hydraulic solenoid out, and while it was out, checked the finger screen behind the valve for any debris and found none. With the new valve in place, the problem is exactly the same, so I am left scratching my head a bit as to the cause of this.

Since the valve was replaced and the symptoms are the same, I feel it's safe to rule out a bad hydraulic valve, which was my first suspicion. It would not seem to be an electrical issue, as the solenoid is clearly getting the command to advance or retard from the DME, just doing it too slowly. That leads me to think that this must be an oil pressure/ flow issue somewhere, either before the solenoid valve, or after the valve in the actual vane cell adjuster. When I pull the valve out it is full of oil, so clearly oil is getting to the valve, and as to how to measure the actual pressure there, I really don't even know where to begin on how to do that. On the other end, the vane cell adjuster just hydraulically floats, and takes position from wherever oil pressure pushes it to, so I can't really figure what could go wrong in there.

What is surprising, is that the car does not throw fault codes for this. One would think that since the DME knows what degree of cam advance or retard it wants, and also knows that there is a difference in values from one bank to the other that this would throw codes, but it does not.

I'm really stumped on this one, so any and all ideas are welcome.

[JFP in PA]

I have been having issues with drivability and after diagnosing with the PST, I have a "laggy" valve advance on Bank 1-3, where it would take considerably longer than Bank 4-6 to advance, and while it was "taking it's time" to advance on acceleration the car would cough and sputter. Today i changed the valve phasing hydraulic solenoid out, and while it was out, checked the finger screen behind the valve for any debris and found none. With the new valve in place, the problem is exactly the same, so I am left scratching my head a bit as to the cause of this.

Since the valve was replaced and the symptoms are the same, I feel it's safe to rule out a bad hydraulic valve, which was my first suspicion. It would not seem to be an electrical issue, as the solenoid is clearly getting the command to advance or retard from the DME, just doing it too slowly. That leads me to think that this must be an oil pressure/ flow issue somewhere, either before the solenoid valve, or after the valve in the actual vane cell adjuster. When I pull the valve out it is full of oil, so clearly oil is getting to the valve, and as to how to measure the actual pressure there, I really don't even know where to begin on how to do that. On the other end, the vane cell adjuster just hydraulically floats, and takes position from wherever oil pressure pushes it to, so I can't really figure what could go wrong in there.

What is surprising, is that the car does not throw fault codes for this. One would think that since the DME knows what degree of cam advance or retard it wants, and also knows that there is a difference in values from one bank to the other that this would throw codes, but it does not.

I'm really stumped on this one, so any and all ideas are welcome.

Knowing that this is a recently assembled engine, are you sure there isn't anything obstructing oil flow (I have seen problems when people put too much sealant on surfaces and it ends up where it does not belong over time)? These actuators need both pressure and a level of flow volume to work correctly...what kind of oil pressure does the engine have?

[Cloudsurfer]

I have been having issues with drivability and after diagnosing with the PST, I have a "laggy" valve advance on Bank 1-3, where it would take considerably longer than Bank 4-6 to advance, and while it was "taking it's time" to advance on acceleration the car would cough and sputter. Today i changed the valve phasing hydraulic solenoid out, and while it was out, checked the finger screen behind the valve for any debris and found none. With the new valve in place, the problem is exactly the same, so I am left scratching my head a bit as to the cause of this.

Since the valve was replaced and the symptoms are the same, I feel it's safe to rule out a bad hydraulic valve, which was my first suspicion. It would not seem to be an electrical issue, as the solenoid is clearly getting the command to advance or retard from the DME, just doing it too slowly. That leads me to think that this must be an oil pressure/ flow issue somewhere, either before the solenoid valve, or after the valve in the actual vane cell adjuster. When I pull the valve out it is full of oil, so clearly oil is getting to the valve, and as to how to measure the actual pressure there, I really don't even know where to begin on how to do that. On the other end, the vane cell adjuster just hydraulically floats, and takes position from wherever oil pressure pushes it to, so I can't really figure what could go wrong in there.

What is surprising, is that the car does not throw fault codes for this. One would think that since the DME knows what degree of cam advance or retard it wants, and also knows that there is a difference in values from one bank to the other that this would throw codes, but it does not.

I'm really stumped on this one, so any and all ideas are welcome.

Knowing that this is a recently assembled engine, are you sure there isn't anything obstructing oil flow (I have seen problems when people put too much sealant on surfaces and it ends up where it does not belong over time)? These actuators need both pressure and a level of flow volume to work correctly...what kind of oil pressure does the engine have?

I've completely thought of this as well. Oil pressure is good, 4-5 BAR, the question is, how can I verify sufficient pressure and flow at the hydraulic solenoid port, which would be the oil entering the valve?

[JFP in PA]

That is going to be complicated…………only way I can envision is to push oil from a pressurized container thru the system from the oil pump side with each actuator alternately removed, as you obviously cannot do this with the engine running. Another possibility would be to push compressed air backwards through the system; I'm trying to think of any downsides to doing this (like how the pressure control valve and spring in the oil pump would respond), and cannot think of any problems pushing air backwards might cause, but I cannot think of anything problematic. Before you assembled the engine, did you blow out the passage ways? Sometimes machine work and block cleaning leaves small bits of trash in these passage ways……… There is also the possibility you may find that one bank has a leaking oil passage way that is bleeding off the oil pressure on one side, but usually that shows up somewhere else, like oil in the coolant.

I'm afraid that none of these "Easter Egg hunt" diagnostics are going to be easy or quick………..

[Cloudsurfer]

That is going to be complicated…………only way I can envision is to push oil from a pressurized container thru the system from the oil pump side with each actuator alternately removed, as you obviously cannot do this with the engine running. Another possibility would be to push compressed air backwards through the system; I'm trying to think of any downsides to doing this (like how the pressure control valve and spring in the oil pump would respond), and cannot think of any problems pushing air backwards might cause, but I cannot think of anything problematic. Before you assembled the engine, did you blow out the passage ways? Sometimes machine work and block cleaning leaves small bits of trash in these passage ways……… There is also the possibility you may find that one bank has a leaking oil passage way that is bleeding off the oil pressure on one side, but usually that shows up somewhere else, like oil in the coolant.

I'm afraid that none of these "Easter Egg hunt" diagnostics are going to be easy or quick………..

This is exactly what I was thinking last night. Thing is, I'm not entirely sure what the exact flow schematic looks like as to how oil gets from the oil pump, up through the case half, through the head, through the lifter assembly, and into that solenoid valve. Everything was meticulously cleaned during assembly, so the only thing that seems plausible now is that either something, I'd guess likely a small piece of extra sealant, broke away and is now plugging the supply to the valve, as I just can't see anything plugging the small bit of plumbing from the valve to the vane cell adjuster, or there's something wrong with the actual vane cell adjuster and/or cam (which I still think is unlikely, but hey, stranger things have happened). I'd ideally like to find some scientific way to measure both pressure and flow volume at the solenoid supply and compare this side to side (4-6 works fine, 1-3 is the issue, so if there's a significant difference in pressure or flow that would indicate the problem- of course next would be solving it). What's maybe easier, would be blowing air backwards through it, as if anything was plugging the passage it should get freed up, though who knows if said piece of debris would wind up in the sump and get picked up by the filter, or get pushed back into the same place it was and re-plug the passage, or maybe worse plug something else.

What's perhaps most frustrating in my mind, is that I never ran this engine before it came apart to get sleeved, so for all I know either a case half or head simply has a bad passage and is bleeding pressure off internally. For the record, there is no intermix going on, and I'm inclined to agree that if it was a bad passage somewhere that bled off oil would likely end up in the coolant, so perhaps that's somewhat reassuring.

Hypothetically, would any harm come from running the engine with one of the valves removed at a time? The cams simply default to zero advance without pressure, so I can't see anything bad coming from that (shoudln't be remotely possible to punch a piston to a valve). I had thought of pulling the spark plugs and just rolling the engine with the starter with one valve removed at a time and compare readings.

Does it seem likely that if something is plugging the supply side that blowing air back down it backwards would free it up? That seems like the quickest thing to try, especially since I did discover (for everyone's future reference) that these valves do, in fact, fit through the valve cover, so pulling them out literally takes 2 minutes (in my case, since I'm running B&B Caymans S headers the O2 sensor is right in front of the phasing valve, so must be removed). If you did go down this road, would it maybe be wise to pull the pressure relief from the oil pump housing first? Ideally, I'd like to get whatever is plugging this up (if that really is the problem) out of the engine, not have it floating around to get stuck somewhere else worse (like a piston squirter).

Edited September 3, 2010 by Cloudsurfer

[JFP in PA]

I would be circumspect about running the engine with the actuator removed as the oil pressure loss could cause starvation elsewhere, causing a entirely new set of issues (oil flows from the pump, to the crank journals, then up to the heads). Ideally, you would pull the actuator in question, and then push oil from the pump up to the now open actuator port (you could drain the engine oil into a suitable container, pump from that container through the engine, and let the returning oil drain back to the container). This is going to require fabricating some items (like a small rubber plug with a suitable tube sticking out of it to use at the oil pump, as the pump oil passage is not threaded, and you are going to have to push the plug in and hold it while the oil is pumping. Obviously, an extra pair of hands is going to be useful for this. A good idea would be to do this first with the actuator that is working properly so that you can see what the flow should look like before checking the problematic unit.

Another possibility, and this is a bit of a “wild hare” approach, is to use vacuum rather than pressure. You would need to fab up rubber plugs and lines for both ends (oil pump and actuator port), and add a second collector container on the actuator port end to catch the oil and pull the vacuum from; but this would then become a “one man” operation………….. You could also skip opening up the oil pump entirely, and just use vacuum and the intact oiling system to pull the oil up to the actuator, saving a lot of “wrench time” for the process………

Edited September 3, 2010 by JFP in PA

[tholyoak]

Here are some diagrams of the oil circuit and the oil supply from the 4 way solenoid valve to the vane adjuster on the camshaft. Essentially the solenoid valve is a 4-way proportioning valve that connects one of the control lines ( A or B ) with pressurized oil from the feed line P and open up the other line to allow oil to flow to the crankcase. If the A line is pressurized the vane adjuster is turned to advance, if B is pressurized it retards. In the center position both lines are closed and the cam maintains its current position. Intermediate positions between A fully connected or B fully connected to P are also available allowing for slower but finer changes in cam timing. Therfore the valve controls both the speed and amount of cam timing changes in contrast to the on or off cam timing on the earlier cars. The non-return nature of the valve allows for proper cam timing changes under low oil pressure conditions such as low engine speed and/or high temperatures.

Hopefully, these diagrams don't violate copyright issues on the site as they are taken from Porsche technical publications. If they do I apologize to Loren and feel free to remove them.

-Todd

[Cloudsurfer]

Todd-

Thank you, that is extremely helpful. So, after looking at this schematic, since this is a hydraulic system, that has the issue of performing slowly at low RPMs, I would think the problem could be either in the supply or drain side, as either one would cause too slow of a movement at the vane cell adjuster. Is it reasonable to suspect that the non-return valve on one side is not functioning, and that is why this issue presents itself only at low RPMs? Where exactly is that valve? I know there is a check valve inside the the finger screen that sits directly behind the solenoid valve, is this the non return valve in the diagram?

I suppose the only evidence working against the culprit being the non-return valve, is that this problem actually seems to get better as the engine warms, and the oil thins, so that would point away from the non-return valve being the issue.

Back to the idea of using air pressure to blow out these passages, that seems relatively easy to do to blow out the supply side (P) by blowing air back down that way from the valve port, but to blow out the returns, I imagine you'd have to blow air up from the sump?

[JFP in PA]

The "non return" or check valve is on the oil supply side of the actuator; I think you are correct on where it is located.

[Cloudsurfer]

Does anyone know how different (if at all) the heads from a 3.2 vane cell (04 model year) boxster engine (vane cell variocam, but no "plus" valve lift control) are from the 3.6 heads?. I have the blown 3.2 engine in the stand and am thinking of tearing down the head and doing some diagnostic work to figure out the flow of oil in these things to solve this problem, as I REALLY don't want to tear apart the head on my 3.8, esp with the engine in the car.

Even better, perhaps, does anyone have a 3.6 head laying around? It can be damaged, I just need to study the flow of oil through the head.

The more I think about this, I think it may be more likely that the drain is plugged up, not the supply side, but we'll see soon enough here.

[george996]

Does anyone know how different (if at all) the heads from a 3.2 vane cell (04 model year) boxster engine (vane cell variocam, but no "plus" valve lift control) are from the 3.6 heads?. I have the blown 3.2 engine in the stand and am thinking of tearing down the head and doing some diagnostic work to figure out the flow of oil in these things to solve this problem, as I REALLY don't want to tear apart the head on my 3.8, esp with the engine in the car.

Even better, perhaps, does anyone have a 3.6 head laying around? It can be damaged, I just need to study the flow of oil through the head.

The more I think about this, I think it may be more likely that the drain is plugged up, not the supply side, but we'll see soon enough here.

I would not be so quick to dismiss the check vavle in bank one. The info that I read describes that the function of the check valve is to assist/speed up the actuation when oil pressure is not enough to overcome the force if the vavle springs, etc.. I will try find the description and post it.

[george996]

Does anyone know how different (if at all) the heads from a 3.2 vane cell (04 model year) boxster engine (vane cell variocam, but no "plus" valve lift control) are from the 3.6 heads?. I have the blown 3.2 engine in the stand and am thinking of tearing down the head and doing some diagnostic work to figure out the flow of oil in these things to solve this problem, as I REALLY don't want to tear apart the head on my 3.8, esp with the engine in the car.

Even better, perhaps, does anyone have a 3.6 head laying around? It can be damaged, I just need to study the flow of oil through the head.

The more I think about this, I think it may be more likely that the drain is plugged up, not the supply side, but we'll see soon enough here.

I would not be so quick to dismiss the check vavle in bank one. The info that I read describes that the function of the check valve is to assist/speed up the actuation when oil pressure is not enough to overcome the force if the vavle springs, etc.. I will try find the description and post it.

variocam plus.pdf

[txhokie4life]

Does anyone know how different (if at all) the heads from a 3.2 vane cell (04 model year) boxster engine (vane cell variocam, but no "plus" valve lift control) are from the 3.6 heads?. I have the blown 3.2 engine in the stand and am thinking of tearing down the head and doing some diagnostic work to figure out the flow of oil in these things to solve this problem, as I REALLY don't want to tear apart the head on my 3.8, esp with the engine in the car.

Even better, perhaps, does anyone have a 3.6 head laying around? It can be damaged, I just need to study the flow of oil through the head.

The more I think about this, I think it may be more likely that the drain is plugged up, not the supply side, but we'll see soon enough here.

I have a dead 3.6 head around -- PM or email me mike@lonestarrpm.com and I'll figure a way to get it to you.

Mike

[Cloudsurfer]

Does anyone know how different (if at all) the heads from a 3.2 vane cell (04 model year) boxster engine (vane cell variocam, but no "plus" valve lift control) are from the 3.6 heads?. I have the blown 3.2 engine in the stand and am thinking of tearing down the head and doing some diagnostic work to figure out the flow of oil in these things to solve this problem, as I REALLY don't want to tear apart the head on my 3.8, esp with the engine in the car.

Even better, perhaps, does anyone have a 3.6 head laying around? It can be damaged, I just need to study the flow of oil through the head.

The more I think about this, I think it may be more likely that the drain is plugged up, not the supply side, but we'll see soon enough here.

I have a dead 3.6 head around -- PM or email me mike@lonestarrpm.com and I'll figure a way to get it to you.

Mike

PM sent!

[Cloudsurfer]

Does anyone know how different (if at all) the heads from a 3.2 vane cell (04 model year) boxster engine (vane cell variocam, but no "plus" valve lift control) are from the 3.6 heads?. I have the blown 3.2 engine in the stand and am thinking of tearing down the head and doing some diagnostic work to figure out the flow of oil in these things to solve this problem, as I REALLY don't want to tear apart the head on my 3.8, esp with the engine in the car.

Even better, perhaps, does anyone have a 3.6 head laying around? It can be damaged, I just need to study the flow of oil through the head.

The more I think about this, I think it may be more likely that the drain is plugged up, not the supply side, but we'll see soon enough here.

I would not be so quick to dismiss the check vavle in bank one. The info that I read describes that the function of the check valve is to assist/speed up the actuation when oil pressure is not enough to overcome the force if the vavle springs, etc.. I will try find the description and post it.

George-

Thank you SO much for posting that PDF. I am going to re-check that check valve, and try swapping it out for one taken from another motor.

[Cloudsurfer]

Well, here's what I have to report back. Tried the easy fix of swapping the check valve out on this side. No joy. Then to dig a bit further, realized that since the vane adjusters have a locking pin to lock the cams at their fully retarded position when no oil pressure is present, that I could crank the engine with the valve out and observe oil flow. So, I pulled the fuel pump relay and all 6 coil pack connectors and cranked the engine, first with the Bank 1 valve out, then with the Bank 2 valve out. The Bank 1 valve (the "problem" side) pukes barely a dribble of oil, while the Bank 2 valve gushes out (which is what you'd expect). So, clearly this entire problem is being caused by an oil supply issue to the solenoid valve.

For reference, so we can all learn, the drain from the solenoid valve simply goes through a hole bored into the head that lets oil run back under the area where the chains run. Nothing fancy there. The oil feed hole in the head is a pretty sizable hole, as are the holes up to to the vane cell.

So now, this brings up several possibilities. Given the size of the oil passages in these things, I find it extremely unlikely that anything could be clogging them up, especially considering that 80PSI oil has been flowing through there, any debris would have been pushed through and would be in the finger screen/ check valve. This brings up some far more concerning possibilities:

1. Bad case. Oil feeds up from the bearing carrier, through the case halves, and then into the head. If there was a crack or other damage to the oil passage, it would bleed pressure off.

2. Bad head. See #1.

3. Head gasket. Incompatibility between 3.2 Boxster S case half, 3.6 Carrera head and 3.8 997 head gasket.

4. Assembly error. I'm not really sure what I could have screwed up, but it's possible that something isn't right.

I originally exchanged my 3.6 case halves for what I was told were a set of 3.4 cases that had already been sleeved by LN Engineering, which turns out to be a pair of 2000 3.2 Boxster S halves. I asked Charles at LN multiple times if there would be any compatibility issues running 3.6 heads with these case halves and was told "no." Due to the engine's 99mm bores, a 997 3.8 head gasket must be used.

The compatibility problem already turned out to be not quite so simple, as I had to modify the case to accept the newer AOS (the older style has a fitting on the AOS itself, which fits into a boss on the case half, where the newer style has a hose nipple that connects a small hose to another nipple on the case, so I had to machine a hose nipple and install it in the case) as well as the fact that the chain housings are a bit different where the heads bolt. On one side I had to drill and tap one hold into the case, while on the other side there was simply no way to use the 4th 6mm bolt. I do not know if these differences are the extent of what separates a 3.4 (or in actuality 3.2) case from a 3.6 case. Given all that, it would seem entirely plausible that the oil feed from an older VarioCam case is different from a newer VarioCam Plus case and that on this one bank, the holes between the case and head do not line up 100%, and for all I know the head gasket could be part of that problem as well.

Unfortunately, the only thing I have at my disposal to tear down and examine is a 2004 3.2 Boxster S motor, so I can't really compare all these different possibilities.

All said, I'm really left scratching my head and dreaming of all the nasty possibilities that I don't want to be the cause of this, and I'm not at all excited to have to pull the engine out of the car and tear things apart. I'd appreciate any insight into this that anyone can share, and to date, certainly appreciate all the help I've received thus far.

[cnavarro]

I'll note that if there wasan incompatibility, you would likely witness the problem on both sides, as theheads and case halves are pretty much mirrors of one another.

I have a 3.6 case as well asa 3.2 and 3.4 case in the shop – I'll compare them all closely again, just tosee if there is any glaring differences, but we've interchanged cases beforewithout any issues. I also have a 3.4 and 3.6 head that I can compare.

A 3.4 head can be used on a3.6. I have had several shops do this. That would verify that the same could bedone with using a 3.6 head on a 3.4, which I just also had another shop reportdoing.

The only difference is indeedin the cam box area between earlier and later cases, but they are so close wecan get away with using the 997 head gasket and adding/subtracting fasteners as needed (which you already did).

Other than cam boxes andair/oil separator (which would require the mod you did or to use an earlier AOS,the blocks are pretty much indistinguishable.

I just compared crankcarriers from a MY06 3.4 Cayman (which needed replacing) to an assembly from a 99 3.4 996 and everything was interchangeable, suggesting there were nodifference between oiling passages between the earlier 3.4 case (non v-camplus) and late 3.4 (v-cam plus). Although I have not personally witnessed a 3.6crank and carrier be installed into a 3.2/3.4 block, the M96/M97 engine shares a modular design which makes the later (longer stroke) crank and carrier be interchangeable. I have been assured it is interchangeable.

I'll report back what I find.

Edited September 9, 2010 by cnavarro

[Dharn55]

Sorry you are having these challenges. Reading through this and the VarioCamPlus PDF makes me realize how much simpler my 3.4 VarioCam engines cam system is. I am trying to understand what you did with LN Engineering. Did you send them some 3.6 cases and they sent you other cases that had already been sleeved (and were 3.2 Boxster cases that were a VarioCam rather than a VarioCamPlus variety) to save time? If this is the case it would seem that LN should be willing to help out. I sounds like the cases/heads are not so compatible if you have already had to make modifications.

Also, don't discount some contamination in an oil passage. Some of the passages are pretty small and a flake of metal from machining could wedge in one and cause decreased oil flow. I hope this dones not mean a total teardown, but if this is the case maybe LN would exchange the cases for true 3.6 cases.

[Cloudsurfer]

Sorry you are having these challenges. Reading through this and the VarioCamPlus PDF makes me realize how much simpler my 3.4 VarioCam engines cam system is. I am trying to understand what you did with LN Engineering. Did you send them some 3.6 cases and they sent you other cases that had already been sleeved (and were 3.2 Boxster cases that were a VarioCam rather than a VarioCamPlus variety) to save time? If this is the case it would seem that LN should be willing to help out. I sounds like the cases/heads are not so compatible if you have already had to make modifications.

Also, don't discount some contamination in an oil passage. Some of the passages are pretty small and a flake of metal from machining could wedge in one and cause decreased oil flow. I hope this dones not mean a total teardown, but if this is the case maybe LN would exchange the cases for true 3.6 cases.

Correct. As I understood it originally, I was getting back 3.4 cases that had been sleeved to 99mm, but after decoding the engine number on the cases, it turns out they are 2000 Boxster S 3.2 case halves. Hypothetically, this should not matter, but clearly, something isn't right. As stated, I have had to make modifications to the cases to interface with the VC+ heads, and I'm not 100% sold that is the end of it.

The earlier chain tension based VarioCam is MUCH simpler than the vane cell based VarioCam Plus system is.

Hypothetically, just to toss this idea out there, but what does the gang think of the idea of simply re-writing a software map for the DME to disable the valve phasing control below, say 2500 RPM, so that it would only actuate once there was sufficient pressure at that port? I realize this is a complete mickey mouse fix, but given that once the engine warms the only time it ever goes below that is when leaving a stoplight from idle, I would be more than happy to live with it.

Charles- I am anxiously waiting to hear what you find.

[cnavarro]

A suggestion made to me by one of my friends was to remove the cams on the affected side and closely inspect the intake cam, especially the rings and bearing that is closest to the vane-cell adjuster as this component is not really described in the literature that has been posted and has been associated with problems like lagging cam actuation. He also said to look for deep grooving/wear on the bearing and proper orientation of the bearing. Also you might also want to check for a loose central screw that secures the vane cell to the cam.

Yesterday was the first time I heard from Patrick of any issues with his build, if I had known earlier, I would have been more than happy to help in any way I can to get to the bottom of this.

Edited September 9, 2010 by cnavarro

[Cloudsurfer]

A suggestion made to me by one of my friends was to remove the cams on the affected side and closely inspect the intake cam, especially the rings and bearing that is closest to the vane-cell adjuster as this component is not really described in the literature that has been posted and has been associated with problems like lagging cam actuation. He also said to look for deep grooving/wear on the bearing and proper orientation of the bearing. Also you might also want to check for a loose central screw that secures the vane cell to the cam.

Yesterday was the first time I heard from Patrick of any issues with his build, if I had known earlier, I would have been more than happy to help in any way I can to get to the bottom of this.

That was where my thinking was going until I did my little oil flow experiment yesterday. There was a marked difference in oil flow from the Bank 1 feed port to the Bank 2 feed port, so that would certainly seem to the culprit. If that's the case, I'm not sure it makes any sense to spend the time and PITA factor to pull the cams from Bank 1 and swap out vane cells, etc.

On that topic, however, does anyone know if the 03 and later Boxster engines that use the vane cell use the same parts? I have not dug into PET yet to verify this. I have an 03 Boxster motor sitting here with a failed IMS bearing that I can harvest for parts, and had been entertaining the idea of swapping the vane cell guts over from that motor onto the affected side of the 3.8.

While we're all brainstorming ideas, what options are out there for "normal" cams for these things? While I was building this thing, I had wet dreams about the possibility of fitting "normal" (no variocam BS) cams and solid lifters to this thing and letting it spin past 7K (the engine is all dynamically balanced to .1 gram, has JE pistons, R&R rods, so the bottom end is easily good for it). Obviously that would require some custom software so the DME wasn't super pissed about the non functioning VC+, but it sounds tempting.

I also have access to a complete set of heads from a 997 S 3.8 engine that includes heads, cams, solenoids, etc so that may be an option, which I'm guessing may actually net a power advantage.

Rather than mess around with possible culprits, if I'm going to pull the engine from the car, I want to know EXACTLY what I'm doing and that it will be close to a 100% solution BEFORE I do it.

In thinking, I'm still inclined to think I could easily live with no variocam below 3000 RPM and just "fix" this via software.

For the record, I have absolutely no animosity towards Charles or LN Engineering. He has been extremely helpful throughout this process, and I didn't think much of this problem, as before I started swapping parts out, was 99% sure it was just a bad solenoid. Oh how I wish that had been the case....

Now that we'r here, I just want some solution (and I'm open minded to all 3 scenarios I listed above, in addition to what anyone else can come up with) to get this thing running properly. The thing hauls serious A$$ from 3K up, and this issue only comes into play when you stop for a stoplight and have to accelerate off idle (and even then, if you just ease into it, it's perfectly fine, but if you push a little more, the DME asks for more advance, and then this problem shows itself), so I hate to go tearing things apart just to solve that. :(

[cnavarro]

We spent several hours looking over parts today. A 3.4 Variocam F1 head compared to a 3.4 Variocam Plus head did not have any differences other than in the valve cover area (which is to be expected). Didn't have a 3.6 head after all, but you can see in the overlay photo (did my best, photoshop isn't my forte) the passages are spot on.

Same goes with the block. Similar overlay photo also done (not perfectly photoshopped, but you can see they are the same). Also no differences other than the chain box area and AOS, which are both to be expected.

Here are the comparison photos:

http://picasaweb.goo...feat=directlink

(note: I apologize, file names were lost in the upload, which provided labels for the photos - I hope everyone can make out my sharpie writing on the parts)

Although I don't have photos (as the parts have already been delivered to the customer), the 3.4 carrier from a MY99 was perfectly interchangeable with the MY06 version, although there were some minor casting differences.

There is nothing to indicate physical differences between the blocks and heads other than where the Variocam itself is concerned (and cams, as they are different of course). The Variocam Plus components seem suspect to me, especially if they were harvested from donor engines with unknown history or that suffered a failure.

I don't know if this is an option or not, but perhaps using an RPM window switch to actuate the Variocam Plus, as I've heard is done when later engines are installed in earlier cars, could remedy the problem if a software fix is not possible?

Edited September 10, 2010 by cnavarro

[Cloudsurfer]

Charles-

Thank you for taking the time to do this. I did some studying today myself of a vane type 3.2 Boxster engine and heads, and thoroughly studied the oil flow through the case up to the head and hydraulic solenoid. All of the oil feed to the heads is up through the head bolt bores, and then there are passages machined in the head in the bores to feed oil to wherever it has to go. In the case of the vane cell oil feed, it has its own feed from the upper head bolt nearest the adjuster.

As you can see in the pictures I took, these passages are quite large, and there's really no way that anything could clog these up, and if any debris did get through (up from the bearing carrier), it would have lodged in the finger screen before the solenoid, which again, has been clean each time I've had it out. Further, since this oil comes off the bearing carrier, if there was any starvation issues they would have to be present at a main bearing journal, and if that was the case, the motor would have spun a bearing a LONG time ago.

Examining the head gaskets, no matter how you put the gasket on, or what version of gasket was used, there'd be no way to partially plug up the feed hole, so I think that rules that possibility out.

The 3.6 engine this all started with was intact, and had not suffered a failure, it was merely semi high mileage (75K or so). I did not source parts from several motors to complete this, nor did the motor blow up prior. However, maybe it is time to pull the cams from the engine and swap out vane cell adjusters. I would, however, like to find a way to inspect that oil passage in the head for damage (and obviously contamination), but I have no idea where to get a borescope that small.

I don't think an RPM switch would work for this, as it needs multiple inputs. People have used that type of system to trigger the valve LIFT function, but that would not really work for the valve advance. There is no problem with the valve lift functionality. I have to assume, however, that when a tuner was writing a map for this thing, that the advance could easily be disabled below a certain RPM.

Does anyone know of available of "normal" cams and solid lifters?

[Cloudsurfer]

Well, found my borescope...

http://www.gradientlens.com/bore_products-hpro_microflex.asp

Yikes on the price!!!!

[JFP in PA]

The problem with bore scopes has always been "the smaller the probe diameter, the bigger te pice tag"..............

Edited September 10, 2010 by JFP in PA