'00 boxster base - cam deviation issue
 

A few weeks ago, I was leaving work and came to the first stop light and the car started to have a rough idle and lower than normal rpms, but accelerated just fine. Decided just to get home (stalled a few times). Ran the durametric on the car and found a P0300, P0304, P0305, P0306 and one other I cant remember but had to do with the variocam. I also checked cam deviation and bank 2 was running somewhere around +22, other side about a -8. After much research, I decided it was time to pull the cam cover and see what was going on. I did all this engine in car. What I found was a variocam chain guide on the top completely gone. The bottom one severely worn. The timing chain and marks all seemed in order so no jumped teeth. I figured the missing guide was the problem so I proceeded to put on new guides, reset the timing and put all back together. I did that and ended up with the same rough idle at start up. I went back in with durametric and now the cam deviation is +19. I used the durametric to cycle the solenoid on bank one and it definitely made the engine rpm change. I tried it on the bank 2 but didn;t seem to alter the engine. I'm about to tear it all back down again as I am thinking it is either the solenoid or actuator (or both) that is also the problem in addition to the failed guide. Is there anything else I should check before I tear it down? Can a cam sensor also cause this issue?

I think your on the right track. you know cam timing is ok because you checked timing marks and chains. When you cycled the solenoid on bank 2 and got no noticeable change in RPM that is a strong indicator of a problem. If it was me I would be doing exactly what your thinking.

A bad cam sensor could cause your rough idle at startup but I do not think it has a bearing on the lack of bank 2 to change RPM when you test it with the Durametric.

You could check the cam sensor signal (voltage) on bank 2 with the durametric and compare it to the signal one bank 1 to see if it is close to the same.
BUT bank 2's big cam deviation may affect that voltage signal so not a fool proof test.
I would do that after fixing bank 2's solenoid actuator issue.

Appreciate the help! I will check that on the durametric, but I'm probably just delaying the inevitable lol!

I had similar symptoms a few months ago - stumbling idle at stop signs or stop lights. Engine ran fine otherwise. The cam deviation on bank 1 eventually was so far out of parameters that the CEL was tripped. I was close to local indy shop and dropped off the car where they eventually replaced the timing chain tensioner - part #99610505158. Car is an ‘02 base with 169,000 mi. Runs great now -

I have the same issue,..only the other bank. I get code P0300, P0301-03 and a P01340
which is solenoid related. I also get a chain type rattle at 2500RPM or so. Do you get that too?

I think i have the same issue as your having. Have you found your answer yet?

I would check the wiring to the bank 2 solenoid first on the off chance that it is a simple connection or other wiring issue. But I think your original assessment is more likely;)

I feel like i did hear some chain rattle before this happened which may have been related to my chain guide going out or being gone.

I read up a little on how to check the solenoid, wiring harness, and signal from DME. Wish I would have read some of this before tearing into the first time. Anyway, I will check those tonight for the solenoid and report back. Although it could be the solenoid, I'm leaning towards actuator since my cam deviation is so far off at idle (+19) and running rough which seems less to do with the solenoid since that only activates at higher rpms. Maybe it's both, who knows at this point.

I have 160k miles on the car.

So I will be pulling the cover. I checked the signal from the DME and my test light lights up on acceleration. I checked ohms on the solenoid and got 2.9. I hooked up 9V to see if I could make it cycle but no click. Also kept my finger on the solenoid to feel if it was working but got nothing. So the solenoid seems to be dead. In addition to that I was researching some more and a guy mentioned to make sure if you buy a used variocam make sure it has the plunger and spring. Immediately I got a cold sweat because the plunger cane out once and I never noticed a spring come out. Later I noticed the piston sank lower than I noticed before but though maybe it was because all the oil drained out of the actuator. I checked my bench today and found the dang spring!

So the million dollar question is whether or not I got a bad actuator??? Remember my cam deviation was +22 before the guide and after +19 so it is still stuck in advance. Since my plunger is probably all the way down it makes sense now, but would just changing the guide have corrected the previous issue? I’ve got to get a solenoid anyway. Good news is it only took me 1/2 the time to tear down this time lol

Can't answer the million dollar question. But nice work chasing down testing procedures for the solenoid. I always like to find root causes to automotive problems rather then just changing parts. Your doing a good job of that. sounds like your close to resolving your problems:D
Let us know the final outcome.;)

Does anyone know the difference between cam deviation and cam angle? I understand the general principle, but I have some more specific questions. From my Durametric tests, the deviation basically stays the same regardless of rpm. Cam angle changes under load/rpm or mixture of both. So cam angle goes from around the zero mark at idle to +25 or something close to that at higher rpm indicating an advance. However, when I do that, the deviation doesn't change. So now with a faulty actuator/solenoid on the driver side, my cam deviation is +22 at idle. But the cam angles still stay around the zero mark so clearly they are looking at two different things. What I do understand that cam deviation can be a good indicator that your guides are going south by getting increasingly larger negative numbers (going from -2 to something like -8).

If you take a look at the diagram you will see that the actuators in the engine off positions. Does anyone know if this is that actual positions at idle? Does it shift at startup under hydraulic pressure and then the solenoid pushes it back under advance? I'm just trying to figure out how it can fail or get stuck in advance if my solenoid does not work either.

Sorry for my ramblings. If anyone can contribute, let me know. I have tried to find all these answers doing many searches but can;t get to the end of what I am trying to answer.


http://986forum.com/forums/uploads02...1563560762.jpg

I wanted to add two other things. When I start the car cold, it will idle perfectly at around 1000 rpm and after a minute or two (assuming the car goes to closed loop) the rough idle starts.

Also my rough idle stops and the car runs great if I rev it or keep the rpms high which would indicate that the actuator is stuck in advance. After taking off from stop, I can run through the gears no problem.

Camshaft deviation: Amount in degrees the centerline of the intake lobe is from ideal. so should remain steady. or nearly so.
Cam angle: Or lobe separation angle: Amount in degrees of separation between centerlines of intake and exhaust lobes.
I am not positive of this but I think I read that around 1500 RPM, the actuators push out on the chains changing the valve timing. Around 6000?? RPM they kick back out and the actuators go back to the retracted position.

Good News, I'm all done with both sides!!!! Only took me 16 hours over last weekend. So here is how the saga played out. Although I was pretty sure the driver actuator potentially could be bad even though it was missing the spring, I found a solenoid and actuator on ebay for $300 and might be worth the chance. So once I got the part in the mail I realized it was for the passenger side. The listing had it as the left side, however, they did have the part number correct. I missed checking that one digit. But it wasn't all bad. I took it apart and realized the the spring I found on my bench was in fact not the same spring as in the actuator. Decided to keep that unit together maybe to sell and went on a hunt for a similar spring that would work. After buying three different kits, I found one that was near identical. Was picking up some rags on the floor and guess what??? Found the original spring lol. Yikes. So next I decided to check the solenoid on the used actuator because remember I thought my solenoid was dead also. Turns out the solenoid I just got was giving me weird readings like mine so I decided to put a 9V battery on each one and they both worked! So then realized that maybe my meter had a bad fuse. Checked it and yep, a bad fuse. Damn it! So both solenoids work. So these solenoids do not have a loud click to them at all so I can see why they can be mistaken as not working. So here is why I could not hear mine. The solenoid uses the pressure from the actuator spring to return back into the solenoid. So since my plunger was all the way down, I could not hear a click, because it never returned. Anyway, now it's time to decide what to do. After all this, I decide I am going to take my chances and put my old assembly back in and this time with the spring! Everything went fine getting the driver side all back together. Tore through the passenger side with very few issues. Put that side back together and checked timing and looked OK. So here is the defining moment....MY BATTERY IS NOW TOAST SO CAN'T GET THE CAR STARTED! Pumped some volts into it and manage to get it turned over and she purred like a kitten. Hooked up the durametric and let the car warm up. She has a tiny anomaly on the idle but not too bad. Check the cam deviation on the driver side and I am at around -2 which is good so check that off the list. Check passenger side and it is -13!!!! What the heck. So I decided to double check the timing again starting with the passenger side. I notice it is a hair off, but can;t believe that could be it. Anyway, spend some time getting it perfect and check again with durameteric and get a -6. I call it good. Car idles super smooth so don;t feel like there is a reason to mess around too much more. Hit the gas a couple times randomly and the cam angle go to 22-24 which was normal. BIG sigh of relief. Happy to have my buddy back after almost three months.

So here is a picture of the notch at -13 deviation. It is basically off half the notch.
http://986forum.com/forums/uploads02...1564532123.jpg
http://986forum.com/forums/uploads02...1564532446.jpg

Here is the notch lined up as perfect as I can get it. You can do this without a tool.
http://986forum.com/forums/uploads02...1564532186.jpg
http://986forum.com/forums/uploads02...1564532534.jpg

Here is how far the crank moved for that small adjustment
http://986forum.com/forums/uploads02...1564532261.jpg

Here is a random kick of the pedal. Everything seems to be in order
http://986forum.com/forums/uploads02...1564532645.jpg

So also decided to drop the oil pan and check this out. Not worms!!! They are not lying when they say to be careful how much locktight you put on. This was not from me, but what I am guessing from the original locktite from factory
http://986forum.com/forums/uploads02...1564532829.jpg

Here is a picture of the guides from passenger side
http://986forum.com/forums/uploads02...1564533140.jpg

Picture of the driver assembly ready to go back in (wish I would have noticed the plunger is down!!!)
http://986forum.com/forums/uploads02...1564533271.jpg

Here is a picture of what it looked like when I first took it out, no guide!
http://986forum.com/forums/uploads02...1564533465.jpg


I didn't find either side to be particularly easier than the other. They both had their challenges.

So in summary, what I believe probably happened was that when the guide completely disintegrated, the computer saw the deviation to be too large in the negative direction and threw it into full advance to protect the motor. I read somewhere that they fail in full advance. I wish I had checked the connector from the DME to the solenoid before I tore everything apart to see if it was forcing the solenoid on full time to keep it in advance. This is the only thing that would make sense at this point as my solenoid and actuator are fully functional.

Anyway, hope this can help someone in the future.

Great write up.
Thanks for posting your follow up.
Sounds like all is well now.;)

Great job! Thanks for the additional information once you got it all fixed.