Variocam Issue?
 

The previous owner of my 1997 Porsche Boxster listed the following problem for the engine. "Valve train noise at high rpm. Possible variocam solenoid bad. No issue at low rpm." The following codes showed up when I revved the engine or were already set when I hooked up my reader. P0300, P0301, P0302, P0303, P0341, P1319, P1313, P1314, and P1315. I did experience the misfires without driving the vehicle and I understand what they mean ... trouble with bank 1 misfire and possible camshaft sensor issues. The emission codes are just warnings because of the misfires. Stop driving to prevent damage. So far I have checked and confirmed good camshaft sensor and compared both variocam solenoids at about 12.7ohms with good voltage to both. I can also hear them clicking when testing with my power supply. Having worked with many types of solenoids, I know they can test fine, but not really work well as they age. The car has 86000 miles and the documented history is not the best. I have also read through many posts from various sites related to this similar issue and still do not have an "Aha", idea to run with. Spark plugs were extremely worn and coils looked good ... and there was no signs of broken plastic parts or metal in the oil or filter.

I am leaning towards timing chain wear or more likely tensioner pad wear even though I haven't seen evidence so far. I want to pull bank 1 side head cover and visually check the tensioner pads. Do I need the special P253 tool or just something to hold the ends of the camshafts in place in order to pull the cover. I don't mind being a perfectionist, but the KISS method works best for me.

Lastly, there is a loud rattle for about 1 second on start up and read this may be normal and using a different grade oil may reduce this ...

Is it possible due to failing IMS since it is driving bank 1 to cause these symptoms?

Just want some input from those who have experienced similar situation. Thanks for any input and have a great day.

Be more optimistic, you are having misfire codes Install new spark plugs & see what happens after clearing all the codes. If one cylinder misfires it can cause the next cylinder to misfire. Be sure all coil leads are properly installed.

Thanks for the reply ... just finished replacing Bosch FR6LDC with Bosch FR7LDC+. All were very worn but only bank 1 misfires so far ... see attached photo.http://986forum.com/forums/uploads02...1607472405.jpg

I can only go on what information was given and what I have read so far ... this is my first Porsche project ... so there is a large learning curve. If it turns out to be just some badly worn spark plugs to have it run smooth, that would be great. She wasn't treated well and I enjoy the challenge.

From the looks of the oil on that plug, your plug tubes are leaking.

That is an affirmative ... I was debating with myself on whether to buy a puller or just use a makeshift long bolt head to remove them and replace with the new ones that arrived this week. I can always stock my toolbox, but as I get older and hopefully a little wiser ... I've learned to adapt with what I have on hand. I am sure they are the original and unfortunately, o-rings don't last forever. Could be a little or a lot stuck though. Had any issues removing these?

A T-handle boat drain plug works well to pull the plug tubes.

I used the long bolt head "tool" and it works just fine. Hook it behind the tubes and they pop out just fine. Good luck and welcome to our world.

And, if anyone is interested, somebody in the aftermarket (Rauch and Spiegel) now makes the tubes in aluminum, totally eliminating the tendency for the OEM plastic tubes to deform and/or crack over time.............

https://www.rauchandspiegel.com/wp-c...352-1new-1.png

Those looks beautiful. I just replaced mine with new plastic tubes. Otherwise I could try to justify buying a set of these. Maybe I’ll find a set in my stocking this Christmas. I hope!

Good Ideas All
 

Thanks for the replies ... I like the boat plug method, unfortunately I sold my boat about 10 years ago. I tried several different make shift tools ... the head of a carriage bolt and a set of measuring calipers slightly modified. The tubes did not want to let go so I ended up removing the outer plastic to remove the large o-ring and then they decided to let go ... I hope I did not get any pieces into the head as they were very brittle.

The Rauch and Spiegel aluminum tubes look like a great idea ... I will probably get these if I do need to remove the head covers to replace solenoid or timing chain pads. I noticed that they also sell the puller tool ... tempting, but I'll hold off unless I decide to work on future Porsche Projects.

I plan to drop the car off the jack stands this evening or tomorrow and test the engine for repeat codes.

Same Problem with More Information
 

Well ... pulled the car out of the garage for testing. Fired up engine with new air filter, fresh fuel, oil, and spark plugs. The engine codes reappeared. Misfire on bank1 with camshaft position code P0341. I did notice that the engine ran fine until the secondary air blower timed out. If I let the codes set at idle ... which is rough, I could clear them and then slowly raise the RPM's up to about 2600 when I heard the timing chain rattle. Reset the codes and was able to hold the RPM's steady at about 1850 without any misfires.

So, I would like some input on what to try next. Idle at engine full temperature is rough due to the misfire detections ... but at cold startup idle is good until secondary air timeout. Able to hold RPM's up with no misfires.

What do you guys think?

P0341 is as you know cam position sensor1: signal implausible/implausible operating range/malfunction.
You stated that you tested it.
Did you test to see if signal is getting back to the DME over the entire operating range?
If everything tests good with the Cam position sensor and wiring then I would look at Camshaft deviation and Camshaft timing on bank one.

What tool ... that is reasonable would be best to look at the signals? I only have MBII iCarsoft tool that I use with my Benz. I am able to read live data, but not much ... o2 sensors, TPS, fuel demand, rpm ... it also has o2 sensor tests that seem to be good. I guess I will find the computer (DME) and check connections and double check for bad or rubbed wires.

If you could get something like the Durametric or a Foxwell that reads cam deviation or cam angle. one of those would work.
I have both. on either scanner I can look at Camshaft deviation on each bank.

I can also look at actual cam angle while the car is running so I can compare one bank to the other to see if they are close to each other or are the numbers way different from one bank to the other.
That is what I would want to look at in your case with the sensor testing good.

If your tool is able to test the cam position sensor and it tests good then it is probably ok. I believe the scanner is reading what the DME sees.

Which Foxwell reader?

I have the Foxwell NT520 PRO

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.

Thanks ... appreciate your feedback.

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.

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.

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..

Same Issues
 

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 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.

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.

It all makes sense, just one more thing to consider: changing valve timing not only affects performance but influences emission directly as well. So if it`s not working, that on its own should trigger CEL. When I did this test, CEL lit up when I hit the throttle.

Yes if the valve timing change cannot be compensated for with fuel trims and ignition timing. It would most likely set the CEL on the first event.
Interesting piece of kit that OBDII

Never thought of it that way ... protect cats ... one of the last cars I rebuilt required a new cat because it was melted and rattling around ... never gave a code though ...

Which code set?

Yes, very helpful or leads one in the wrong direction ... it is easier to diagnose if I had full engineering specs to go by ...

I left the variocam unconnected and drove around the block and it ran fine up to 25mph ... so I am left to pull the bank1 head cover and take a look at the variocam ... checking for anything odd such as really worn pads. Might be able to get to it this week ... just need to make a hold down tool for the cams. I'll update my progess ... thanks again for all of the input.



:cheers:

Hey good luck with it. Keep us posted;)

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

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 ...

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.

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

Telltale Particles
 

Dropped the oil cover today and found signs of wear ... one piece of aluminum. I also noticed tiny, tiny particles of metal in the oil ... most likely from the cover sump area itself collection over time. I also noticed the fingerprints of whomever was the last person to install the cover.http://986forum.com/forums/uploads02...1607973339.jpg

The plastic looks to be the color of the Variocam actuator pads.
The metal particles and possibly the piece of aluminum could be from an actuator as well.
Looks like cam cover removal is next:eek:

Yep, don`t bother with the camera...

Might as Well Dive in
 

Is it necessary to hold the cams in place to remove if I have to pull them anyways?

It`s recommended. Only one side of the cams is held down if you pull the cover which will expose the cams to a single sided stress because of the pressure from the valve springs. The camshafts are basically rigid steel tubes and they may break. The chance is not high that they will break, but they can. And you will need to hold them down once you put the cover back on, so you need a tool. You can get a set for cheap on ebay or amazon, or you can make your own. My build thread has pictures about the set I used, that may give you an idea if you wanna build your own.

Good luck!