Variocam Issue?

[blue62]

Originally Posted by freserf

Here is another symptom maybe you can help me with ... I am still not quite sure how this variocam system works. When are the solenoids activated? Does the actuator float under oil pressure when the solenoid is not activated? The reason I ask is this ... I just unplugged bank1 solenoid and now I can rev and idle without the timing chain noise as I experienced earlier. But, I still have bank1 misfires on all cylinders without the P0341.

I'll probably swap coils this weekend to rule them out for the misfire.

I am guessing that the solenoids are active from engine on to about 2800 rpm's or when demand is high? I read somewhere about the basics of the variocam system, but nothing detail related to when it is active.

Thanks for the input ... it is always helpful to learn from others.

If I understand the system correctly: When the solenoid activates it exposes oil ports which allows oil pressure to force the Variocam actuators outwards against the cam chains. Thus changing cam timing. I think this happens at around 1500-1800 RPM then it kicks back out around 5000 RPM.

If you do a search here on the forum I think you could find a more detailed explanation then the very brief one I have given. You should also be able to find the precise RPM range that the system operates in as well.

[freserf]

Thanks ... appreciate your feedback.

[Homeoboxter]

Yes, the changeover takes place at 1500 rpm, then it goes back to default at 5500. The actuators moves to the opposite direction, one is pressing down the chain toward the crankshaft while in the other bank the actuator presses the chain toward the valve cover, this way the intake cams will be advanced by 25 degrees. Check out this video and the descrioption, this will give you an idea how it works:
https://www.youtube.com/watch?v=xmNduI2lRbA&t=10s

If you disconnect the solenoid the CEL should come up and the car should become sluggish.

[freserf]

I actually watched that video about a month ago ... very good for showing actual activation and deactivation. Forgot about it though ... so now my understanding is that variocams are activated with power on ... then it requires temps between 0-133C, rpm greater than 1300, and throttle greater than 5%. Or, temp greater than 133C, rpm greater than 1480, and throttle greater than 4%. Variocams deactivate above about 5000 rpm. It was a good design for its time.

I did not see a code for the solenoid after unplugging it ... I'll let it run through operating temp to see if it sets. I am getting ready to swap coils to see if the misfires change sides. Will update later this evening.

[Homeoboxter]

Originally Posted by freserf

I did not see a code for the solenoid after unplugging it ...

I can`t remember now in what circumstances my car threw the code last time I tried this: only one solenoid was disconnected or both. If the CEL and the code is triggered because the camshaft position sensor detects a difference between the banks, then you will only see the error code popping up if you disconnect only one bank (if both work). I`m just guessing though..

[freserf]

Just swapped coils 1, 2, 3 to 4, 5, 6 with same result. If the bank1 variocam solenoid is connected it will give P0341 when rpms go past 1300 to 1500 depending on temperature. The activation of the solenoid is pushing the camshaft position sensor numbers out of wack thereby giving the code.

Also the misfire stayed on cylinders 1, 2, 3 with the emissions warnings. When I disconnect bank1 variocam, no P0341 but still have misfires. No misfires if I clear the faults and keep rpm's above 1000.

There are no timing codes, just chain rattle when the variocam kicks in if I quickly demand throttle. Without the variocam connected I can throttle to about 3000 rpm before I here significant chain rattle.

So I need to find out what is causing the misfires first ...

New sparks plugs, coils seam to be working normally. Battery is new, but haven't checked the charging system voltage yet. I assume charging is ok since there is no battery light on the dash.

[blue62]

Just for general information:
An important fact to remember when dealing with OBDII and it's related codes.

OBDII is not about engine performance!!!

It's primary function is Catalytic Converter performance.
It doesn't care about engine performance until that engine performance degrades to the point that it becomes harmful to the Catalytic Converter.

With that in mind:
Events such as misfires will set a code and the CEL on the first event.
Why??? Because misfires are immediately harmful to the Catalytic Converter.

An event that would cause a code for say a bad MAF sensor or a slow signal from an O2sensor needs two back events under specific conditions to set The CEL.

On the first event the corresponding code will be logged in the Pending codes memory.
If the event occurs on the next drive cycle, startup, as a back to back event.
The code is moved from pending to permanent and the CEL is lit.
If the event does not occur twice back to back then the codes is removed from the pending codes memory.


So Freserf:
If your reading this, if you unplug the Variocam solenoid and you do not get a code perhaps the DME/ECU does not see it as immediately harmful to the Cat.
So look in the pending codes on your scanner.

Hope this info helps in some way.

[blue62]

Originally Posted by freserf

Just swapped coils 1, 2, 3 to 4, 5, 6 with same result. If the bank1 variocam solenoid is connected it will give P0341 when rpms go past 1300 to 1500 depending on temperature. The activation of the solenoid is pushing the camshaft position sensor numbers out of wack thereby giving the code.

Also the misfire stayed on cylinders 1, 2, 3 with the emissions warnings. When I disconnect bank1 variocam, no P0341 but still have misfires. No misfires if I clear the faults and keep rpm's above 1000.

There are no timing codes, just chain rattle when the variocam kicks in if I quickly demand throttle. Without the variocam connected I can throttle to about 3000 rpm before I here significant chain rattle.

So I need to find out what is causing the misfires first ...

New sparks plugs, coils seam to be working normally. Battery is new, but haven't checked the charging system voltage yet. I assume charging is ok since there is no battery light on the dash.

Just a WAG on my part:
I would say the cams on bank one are getting far enough out of time to cause the misfires.
Chain rattle says loose chains.
P0341 indirectly points to Cam timing issue.
And you have looked at and changed plugs and coil packs.
But I am just guessing.

[Vza]

I had to replace my solenoid for a list of codes. Codes will cause a cascade effect making it difficult to find the root of the problem. If you hear your solenoid thats good at least you know they're working. The durametric allows you to turn various systems of the car on and off. You can activate either solenoid and hear the engine note change. You can also see your cam deviation to see if your timing is set within spec. I think it was + - 6. Misfire codes will get thrown if your timing is off....i would take a look at your cam deviation. Sometimes durametric sells returned items for a discount. You can call and ask. V

[freserf]

Thanks ...Depending on what I find with the bank1 variocam ... I'm pretty sure that something is amiss inside causing the P0341 when the solenoid is activated ... my best guess is one or a combination of problems. Variocam actuator, timing out of time, or lastly, or, etc.

I'll visually check the timing first and then proceed from there ...

[Homeoboxter]

A simple check is if you just pull the green plug at the cam position sensor and take a peek onto the variocam with a mirror and a flashlight, or borescope if you have one. If the pad is disintegrated or badly worn you should be able to see that. In my car it was completely broken off and caused the timing jump.

[freserf]

That does sound correct ... I was getting my old smartphone out so I could attach my endoscope camera ... I'll post the results ...