Camshaft Deviation Values

[Cloudsurfer]

I have an LN sleeved 3.6 X51 based engine (that is now a 3.8). I purchased the timing tool kit from Baum when I built the motor, and triple checked everything before the thing went into the car. Now, when reading the deviation values off the Durametric tool (also curious why the PST does not allow you to see this?), I get 5 on one bank and 7 on the other. I then went as far as re-checking the timing with the engine in the car (which is a HUGE PITA), and things are spot on. So, why do I not get a reading of 0? 5 and 7, respectively, seem absurdly high, yet I am told that as long as the value is under 8 it is ok.

I realize that on the intake, it may be a bit of a non issue, as the VarioCam can move the cam to wherever the DME wants it, but the exhaust is fixed, so any error that is in the system is always going to be there.

Can someone here shed some further light on this? I'd really like these values to read 0!!!

[Cloudsurfer]

Anyone? ......

[Loren]

This is a 3.6 liter in a Boxster?

If so, which DME are you using?

[Cloudsurfer]

It's a 3.6 X51 based engine, which is now a 3.8 courtesy of LN sleeves and JE pistons and R&R rods. Car is a 2003 Boxster S with 7.8 DME, coded as a 996 3.6 X51 RoW program.

[tholyoak]

I'm curious why you say the pst doesn't allow viewing it. You certainly can. See this post for an explanation of cam deviation.

[Cloudsurfer]

I'm curious why you say the pst doesn't allow viewing it. You certainly can. See this post for an explanation of cam deviation.

http://www.renntech....__1#entry175209

That post was VERY informative. Thank you.

What section of the PST menu is this available under? I've looked under "actual values," "drive links," etc and I can't find it. That said, I have been reading the numbers off the Durametric, so however you get the numbers, for a VarioCam Plus motor, what should I be looking at to verify things?

[tholyoak]

Go to actual values, hit F5 (filter) this will bring up a number of predefined actual value subsets including all possible actual value data. If you select engine, the camshaft deviations will be there. You can also create your own filter subsets containing the values you want to look at together as a group. The deviation values are the same for the later motors as the early motors, the total advance is simply greater

and not actuated in an all or none fashion but via a pulse width modulation of the solenoids making them infinitely adjustable. Seeing you used the factory tools and the fact that the tabs for the hall sensors on the cams are easily tweaked they are likely the source of your deviation values being high rather than the actual cams being out of time.

-Todd

[Cloudsurfer]

Go to actual values, hit F5 (filter) this will bring up a number of predefined actual value subsets including all possible actual value data. If you select engine, the camshaft deviations will be there. You can also create your own filter subsets containing the values you want to look at together as a group. The deviation values are the same for the later motors as the early motors, the total advance is simply greater

and not actuated in an all or none fashion but via a pulse width modulation of the solenoids making them infinitely adjustable. Seeing you used the factory tools and the fact that the tabs for the hall sensors on the cams are easily tweaked they are likely the source of your deviation values being high rather than the actual cams being out of time.

-Todd

I'll try this tomorrow. I'm 99% positive I did not damage any of the tabs on the cams when handling them, but who knows.

Should I be comparing the actual values vs the expected values, as opposed to the deviation #?

[Cloudsurfer]

Found the F5 filter, wow is that helpful! As to the readings I'm getting, the deviations are 4 and 5 using the PST (both positive), and when I compare the "spec cam timing" to the "actual cam timing" the values seem right where they should be (0 at idle, and then increasing with RPM), except it appears that the Bank 1 values are "lazy." Possibly bad hydraulic valve on that side? When actuating the valve lift solenoids, all that seems to be fine.

Going down that road, if I remember from when I assembled the motor, the valve covers have to come off to get at the hydraulic valves, yes?

[JFP in PA]

Found the F5 filter, wow is that helpful! As to the readings I'm getting, the deviations are 4 and 5 using the PST (both positive), and when I compare the "spec cam timing" to the "actual cam timing" the values seem right where they should be (0 at idle, and then increasing with RPM), except it appears that the Bank 1 values are "lazy." Possibly bad hydraulic valve on that side? When actuating the valve lift solenoids, all that seems to be fine.

Going down that road, if I remember from when I assembled the motor, the valve covers have to come off to get at the hydraulic valves, yes?

Yes, you will need to pull the cover. You are going to need to lock the cams down prior to pulling the actuator. Before reinstallion, you need to compress the valve using a special tool , or I've also seen it done with an improvised C-clamp setup. More nit-pickey than difficult, but dealer get a ton of $ to do this, I've seen quotes over $3K.....

[Cloudsurfer]

Found the F5 filter, wow is that helpful! As to the readings I'm getting, the deviations are 4 and 5 using the PST (both positive), and when I compare the "spec cam timing" to the "actual cam timing" the values seem right where they should be (0 at idle, and then increasing with RPM), except it appears that the Bank 1 values are "lazy." Possibly bad hydraulic valve on that side? When actuating the valve lift solenoids, all that seems to be fine.

Going down that road, if I remember from when I assembled the motor, the valve covers have to come off to get at the hydraulic valves, yes?

Yes, you will need to pull the cover. You are going to need to lock the cams down prior to pulling the actuator. Before reinstallion, you need to compress the valve using a special tool , or I've also seen it done with an improvised C-clamp setup. More nit-pickey than difficult, but dealer get a ton of $ to do this, I've seen quotes over $3K.....

Well, before I go and do all that, what is the best way to determine if it is, in fact, a bad variocam hydraulic solenoid?

[JFP in PA]

I'm not particularly sure that you can, unless either the PST II or PIWIS has some way of causing the solenoid to function as a test. Generally, when these units go bad, they tend to totally crap out or they become obvious (poor performance, codes, etc.). I have not seen one that ran well or didn’t throw codes............

[Dharn55]

With the 3.4 VarioCam you can test the cam advance solenoids. They are an on/off system and you can activate and deactivate them. Not sure if this would work with the 3.6 VarioCamPlus system which is significantly more complex. Check out this post I did last March which has a lot of info on how the systems work and differ.

Edited August 20, 2010 by Dharn55

[JFP in PA]

With the 3.4 VarioCam you can test the cam advance solenoids. They are an on/off system and you can activate and deactivate them. Not sure if this would work with the 3.6 VarioCamPlus system which is significantly more complex. Check out this post I did last March which has a lot of info on how the systems work and differ.

http://www.renntech....__1#entry171252

Using what system?

[Cloudsurfer]

I'm not particularly sure that you can, unless either the PST II or PIWIS has some way of causing the solenoid to function as a test. Generally, when these units go bad, they tend to totally crap out or they become obvious (poor performance, codes, etc.). I have not seen one that ran well or didn't throw codes............

You can watch the specified angles and the actual angles with the PST. What this shows me, is that in my case, the bank one solenoid appears to be laggy.

Here's the problem I have: I'm not throwing any codes, but the car coughs and sputters just off idle if given moderate throttle input, but, if given a very smooth, minor throttle input, it revs up smoothly. Whether that is the difference between how the DME commands the intake cams to move, and by how much, I'm not sure. However, since I just got this motor into the car, and the fact that the entire setup is anything but stock, it's difficult to say if that is being caused by one bank's variocam solenoid, or by MAF issues, or simply the fact that the motor is going to need a custom tune.

To add more info: The motor was 3.6 based, but now displaces 3.8 liters, with 13:1 compression, and the intake system is all silicone hose and hard pipe, with the MAF (Cayman S MAF to specify, which has the flow smoothing grids) directly before the silicone 90 elbow to the throttle body, and the BMC air filter directly before the MAF, separated by a 90 hard pipe. The throttle body is also mounted "upside down" (with the plug on the bottom, not top) such that it would clear the engine cover in a Boxster. Not sure if it matters for the sake of this discussion, but the intake manifold is also reversed to work in the Boxster. The exhaust is B&B Cayman S headers, into a Fabspeed Cayman S dual canister exhaust. It's currently running the RoW EU2 X51 program so that I do not get faults for having no cats and no secondary O2 sensors.

While the engines cam timing may not be EXACTLY spot on (if it is, in fact, off a bit, that's a while separate discussion to fix), it's certainly within a few degrees, and those few degrees certainly would not cause these issues. I'm also not sure I'm sold on the fact that one bank's variocam solenoid could cause this either, but I've been surprised by smaller things in life so who knows.

Forgot to add.... once the motor is past 3k, loaded or not, heavy throttle or light, it's buttery smooth......

[JFP in PA]

I was referring to which system is capable of test cycling the VarioCam/+ technology to see if it worked correctly. I am aware of the capabilities of the PST II (or the Durametric system) to see the cams relative angles change while the engine is running, but was intrigue by Dharn55's post implying that there may also be a diagnostic method to test them to see if they are working correctly. I read his attachment, which is informative concerning how they function, but could not see anything about a way to electronically (or manually) evaluate their function to see if they are operating in range. Obviously, that ability would be of great value when trying to sort out diagnostics on a relatively stock setup.

That said, with all of the additional complexity of your specific combination, I can understand your reluctance to thru all the effort required in pulling the actuator in hope that it is at least related to your problem. Unfortunately, without a proven electronic diagnostic procedure, I don't know any other method than pulling the actuator and replacing it.

Jake Raby recently had a post on another board concerning what sounded like reaching the limits of the intake port flow at higher compression ratios than stock. Assuming that you have evaluated and eliminated every other possibility (electrical, vacuum, fuel delivery, etc.), I have to wonder if your higher compression and unique intake system somehow enters in to all this. Have you considered contacting Raby?

[Cloudsurfer]

If there were a way to positively, diagnostically test the hydraulic solenoids as opposed to just watching the values as the motor runs across the RPM range, that would be fantastic. I, however, do not know of any way to do that, so if someone does I would love to rule out a hydraulic solenoid issue and just focus on working out the MAF issues and getting the motor happy.

I'm open to ideas from anyone who can give them :)

[Dharn55]

I have the Durametric and it allows you to turn the advance on and off. It has been a while since I did it and I would have to hook it up to remember exactly how I did it.

[JFP in PA]

Interesting, I'll have to look into that......................

[Cloudsurfer]

I have the Durametric and it allows you to turn the advance on and off. It has been a while since I did it and I would have to hook it up to remember exactly how I did it.

I have access to both a PST and a Durametric. If you can find how to test the advance, I would GREATLY appreciate it. Also, is this for a VarioCam or VarioCam Plus setup, or both?

[Dharn55]

mine is the VarioCam. I can't start the Durametric program on my desktop. You have to have the connector plugged in to the car and the ignition on. I also have it on an old laptop but the battery is dead. I will see if I can attach it today and figure out exactly how I did it.

[Cloudsurfer]

mine is the VarioCam. I can't start the Durametric program on my desktop. You have to have the connector plugged in to the car and the ignition on. I also have it on an old laptop but the battery is dead. I will see if I can attach it today and figure out exactly how I did it.

If you get a chance, fantastic, if not, I'll dig in the menus next week when I get a chance.

[Dharn55]

OK, in the Durametric menu go to Motronic, then look for Drive Links. There you have the opportunity of turning on and off the advance mech.

[Cloudsurfer]

OK, in the Durametric menu go to Motronic, then look for Drive Links. There you have the opportunity of turning on and off the advance mech.

Interesting. I will try this out today. Thank you!

[Cloudsurfer]

Well, for all those interested, there is no way to test the camshaft solenoids on a VarioCam Plus engine (though I suspect there is a way to do this on a VarioCam car), as I would guess the difference lies in the all or nothing advance of the early system versus the continuously variable nature of the later system.

What I did do tonight was hook up the Durametric and log actual values for MAF readings, expected and actual cam values for both banks, and O2 voltage for both banks while driving the car around with an "assistant" to monitor. The evidence supports a bad hydraulic valve on the one bank. The problem improves to the point where it's almost not a drivability issue as the motor and oil warms, but the one banks cam readings lag significantly when the DME commands a large change and lags less when a small amount of advance is needed, which is further verified by O2 reading differences when this happens and the car coughs. The MAF is working fine.

My hypothesis is that the valve has not fully failed, but is failing, as it improves as things warm up. Further, since the car runs great from 3k up, I suspect that the difference in oil pressure (more pressure as the RPMs rise) allows the valve to work properly at higher RPMs, but not at lower.

Since one side is working fine, and one is not, would it be prudent to just replace both (which I'm really kicking myself in the *** for not just doing when I built this thing)?

Can someone verify that the part # for the valve is 996 105 303 06? Just want to make sure I get the cam adjustment valve and not the valve lift valve, as the PET doesn't make it very clear which is which. Thankfully, the quoted part is only ~$120, but this is not going to be fun to swap out.