Camshaft position deviation wandering around

Hi all, A few months ago, I picked up a new to me 996.1 C2 (2000) in Ocean Blue metallic with Savannah Beige interior (love this combination). It's been an absolute blast to drive this car! I already had a 1972 Targa which I can't drive in the winter here in the Netherlands, so decided to buy a 996 that I can drive year-round. I expected it to be a bit boring compared to my classic 911 but it's much more fun to drive than I thought! (As you all know.) The IMS bearing was replaced when I bought it (at a respectable Porsche specialist), but I didn't do a PPI at that time. (From reading the forums it's now become clear that this was probably a mistake.) Just recently I noticed that I had never seen the CEL light up when starting the car, which worried me. I just assumed it was somewhere in the row of lights at the bottom of the instrument cluster and didn't know it has its own location. That kind of worried me. I've now bought a Durametric to find out what's going on and got the following fault codes: P0650 - Check Engine warning light open circuit P1115 - Heating power O2S ahead of cat. c. bank 1 P1341 - Camshaft adjustment bank 1 below limit value P1117 - Heating power O2S behind cat. c. bank 1 I cleared the fault codes and drove the car to warm it up, then checked the live camshaft position deviation values. For bank 2, this is at a steady -3 degrees, but bank 1 varies a LOT. I have seen from -5.5 to +9. Not related to RPM. I would just be idling in front of a traffic light and the the deviation would slowly move from 0 to +6 for apparently no reason at all, with the engine just idling steadily. The P1115 and P1117 codes didn't return after clearing them. Obviously the P1341 code returned as soon as the deviation became too large. What could cause this apparent random wandering of the bank 1 deviation? Could it be a faulty sensor? Or maybe a VarioCam problem as described in this thread: https://rennlist.com/forums/996-foru...m-p1341-2.html It seems to me that no amount of chain or chain guide wear would explain the changing values that I'm seeing, so it must be something else. A picture to brighten up this post: Thanks for your help! Cheers, Frederik

I forgot to mention that the car has done 60k miles. Engine pulls strong but has a pronounced �sewing machine� howl to it. More than other 996 engines from what I can tell. From further reading, a randomly changing cam deviation reading could point to a faulty IMSB, but it has been replaced just 1k miles ago. Any thoughts would be appreciated!

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Who replaced the bearing, previous owner or did you have it done? I reread but it's not clear to me. Good read here> https://www.renntech.org/topic/32942...-readingerrors

I had it done when I bought it, at the Porsche specialist shop that had it for sale. Part of the deal.

The renntech.org link unfortunately doesn�t work for me, it seems their server has been down for some time...

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the link works for me. I look at renntech.org regularly

Yes, try this... https://www.renntech.org/forum/2-996...rera-4s-targa/ it's working for me too

Looks like it�s not accessible from Europe. I�ll try later via archive.org or something similar. Thanks!

I've now been able to read the rennlist.org link -- a good read but it's not directly applicable to my situation. In his case the deviation is -12 degrees permanently, while in my case it fluctuates. However, I did another test run yesterday and got some interesting results. I've now also looked at the actual camshaft angles. When cold and idle, they are between -1 and -2 degrees, going to 22...23 when VarioCam is activated above ~2000 rpm. That looks perfect. When the engine is warmed up, the numbers are even better at 0 and 24 degrees, just as they should be. So the chains and wear pads seem to be good. From that point on though, the VarioCam on bank 1 starts to mishave, especially after driving on the highway in the 2500-3000 rpm zone for 10 minutes or so. It doesn't go back to 0 anymore, and doesn't completely activate to 24 either. It will go to +18 for example, and back to 10, then when idling, slowly back to zero. This is what causes the cam deviation value for bank 1 to go all over the place as it appears to be an integrated average over time of the actual camshaft angle. So my conclusion is that most likely, the VarioCam actuator on bank 1 needs to be replaced, much like in this thread: https://rennlist.com/forums/996-foru...m-p1341-2.html Any thoughts on this? And would it be a problem to keep driving the car for a while before this is fixed?

I wonder if it could be a bad cam position sensor? I would have thought you'd get a code, but maybe not? Aside from the numbers, did it feel any different? I would think you'd feel if it was really that far out.

Sounds like the actuator is sticking or a bad solenoid to me , might be worth changing the solenoid, check the wiring as they can get damaged where they come out of the top of the solenoid ?

@JTT: I do get the P1341 error code (cam deviation below limit bank 1). The whole reason I got into this is that I discovered the CEL didn't go on when starting the engine and is broken or more likely, has been removed on purpose. Could the cam position sensor malfunction like this? I don't feel any difference in how the engine pulls, sounds, or behaves, so that's odd. @Noz1974: Wouldn't a bad solenoid just cause the VarioCam to not actuate at all? My feeling (but I'm far from an expert on these engines) is that a bad wire or bad solenoid would cause it to not activate at all, but could not explain the partial activation that I'm seeing. But I could definitely be wrong.

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My bet is the chain guides are worn. Replace the guides along with both bank solenoids. If you have the budget, you may want to consider replacing the chain tensioner assemblies. Just my opinion based on many threads regarding camshaft deviations on the Mk1 996. Good luck!

I'm curious how you would get to this conclusion, seeing that the actual cam angles are almost perfect until the VarioCam system starts to misbehave.

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I'm basing it on the camshaft deviations. Porsche states that repair is needed if there is ever a camshaft deviation (between both banks) that exceeds 6 degrees. Jake Raby states that 4 degrees should not be exceeded. He touches on it in this video. You Tube

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^^^ Exactly ^^^ ! I think what the prof is saying is that it seems to be either the actuators or the solenoids that are faulty (in addition to the pads). It's not to difficult to check these. It's unfortunate that these parts are expensive (the solenoids are a couple hundred $ each and the Actuators are around $ 1k ea. - ouch!) in addition to the labor being expensive (while the engine doesn't have to be removed, it helps to drop it a few inches, and remove the rear wheels and mufflers...).

Well, this might be expensive but it could be a lot worse! How do you check the solenoids and actuators? Any opinion on whether it�s bad to keep driving like this? Like I said, the engine feels great and if the Variocam system is not working well on bank 1, I don�t notice it at all. The idea that it could also be a faulty camshaft position sensor is also intriguing.

Not sure if this helps but sounds like you can disconnect the cams and still run engine. I have NOT tried it but here is some info that might help. I can see my Degrees on my engine thru my Cobb tuner not sure if they have anything for your non Turbo https://rennlist.com/forums/996-turb...-in-boost.html

If sensors, silenoids, actuators are bank 1 / bank 2 interchangeable, that would tell you a lot.

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I would think so. The chain wouldn't have the proper tension and would begin to slap. The solenoids, guides, and tensioner cylinder(s) are unique for the mk1 and not found on the 3 chain 996.2 engine. Apparently, tensioner guide rail wear is common problem as these engine age. I would at least change out the solenoids and chain guide rail (i.e. pads) on both banks. Remember, the solenoids are bank specific. Regardless if you go aftermarket or genuine Porsche OEM, make sure you get the right one installed on the right bank of cylinders.

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Every 99-2001 Porsche needs to have the new updated chain,& ramps replaced with the new & improved parts. I just cleaned & inspected my actuators after 88 K miles &10 years. OE actuators have 141 K miles on them now.

Might be worth getting the cam cover off initially just to see what's going on in there and maybe change the solenoid, that's not too much labour just the rear bumper and heat shields off then the muffler and bracket then the cam cover but be aware of the cam hold down tool needed to support the cams before removing the cover as the cam bearing caps apart from the first two near the actuator are in the cam cover and if you just remove it with out , you can damage the cams etc, it's not too much of a hard job to do if your pretty handy with the spanners, the word bit will probably be the rusted bolts on the exhaust brackets, pisses me off how a porsche is a premium brand with a premium price tag but there never seems to be any extra money in the budget for better fixings, you would think they could stretch to some stainless or brass/ copper nuts and bolts for the exhaust instead of the cheap steel crap that rusts and welds itself on after ten minutes!!! grrrr rant over , breathe!!

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It only has to last 4 years for them.

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I still don't understand why the chain, the tensioners and the guide rails etc would be bad. If that was the case, I would expect to see a large but static cam position deviation, and the actual cam angle values would reflect this. So, on starting the engine cold and idling, I would already have more than +/- 6 degrees of actual cam angle. But what I'm seeing is that my actual cam angles are almost perfect, until the Variocam system on bank 1 starts to misbehave. Or can a not completely activating Variocam cause the chains to lose tension? Are they only tensioned correctly at 0 or +24 degrees?

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It's simple. Anything mechanical wears out over time. These pads have a service life and at 20 years and 60,000 miles, you've gotten plenty of life out of yours. Here is a good picture of how the pads look over time. I guarantee yours will look similar to the dark brown ones. Each bank has a pair of chain guide pads inside the heads. (see picture) Here is the picture from Pelican Parts of the tensioner actuator assembly. Notice the black cylinder in the close up. That's the solenoid. It mounts to the assembly. You'll also notice the pad. There is also one on the bottom of the tensioner actuator. This is not a cheap job, by no means. It requires a lot of work to replace these parts. Make sure you hire a skilled Porsche mechanic to do the job because it involves removing the camshafts. If they botch the job, you'll have serious timing issues. It's my understand that cam shaft deviations will fluctuate, but should never be 6 degrees between both banks. At this point, I think it would be wise for you to take the car to a trusted Porsche mechanic in your area. No reason to have a back and forth over the topic.

Yea but his cam deviations are only all over the place while the virocam is suppose to be activated. U seem to be missing the op's point. He is not have cam deviations beyond 6* while at idle, at least this is how i read it. In the end u may also have chain guide issues too but i think u r on track with an virocam actuator or seliniod issue.

To simplify further if you buy a 2000-2001 Porsche & don't know if the vario-cam ramp pads & chains have been retro-fitted with the new improved parts, you should inspect them.

Thanks all for the insights! I’ll definitely be taking this up with my shop.

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Reread his original post. He states clearly, " For bank 2, this is at a steady -3 degrees, but bank 1 varies a LOT. I have seen from -5.5 to +9. Not related to RPM. I would just be idling in front of a traffic light " If bank 2 is a steady -3 degrees and bank 2 hits +9 degrees, then the OP had exceeded 6 degrees of deviation between bank 1 and bank 2. He then states, " Obviously the P1341 code returned as soon as the deviation became too large. " The car is screaming chain guide wear! What am I missing here? At this point, I think the OP has realized what he needs to do.

Read this thread and specifically Jake Raby's thoughts on the subject. https://rennlist.com/forums/996-foru...s-and-ims.html

You would be 100% correct if the cam deviation was static. But in my case, the deviation sets in only once the engine warms up and the Variocam doesn’t fully activate, and also doesn’t fully return to zero. With my (admittedly limited) understanding, if the pads were worn, I should be seeing deviation all the time. I added this in a later reply — I first didn’t look at the actual cam angles which tell more of the story. Most likely the solenoid needs to be replaced, and maybe also the actuator. In that case, the chain pad can easily be inspected as well. In the best case it’s only a failing sensor but that seems too good to be true.

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If you decide to replace the solenoid, you might as well replace the chain guide pads. Porsche may sell the mk1 "timing chain tensioner" (bank 2 - 99610505358 and bank 1 - 99610505158) as a complete set that would include pads and solenoid. It might not be a bad idea to just replace the whole thing. Please post back when you get it looked at. Good luck!

Will do, thanks!

Porsche does sell an Actuator Assembly (they call it Chain Tensioner) complete with actuator, solenoid, and the pads as well as the little tool to compress it. For some reason, bank 1 seems to need replacement more than bank 2. This is a semi big job and requires some knowledge and tools to get it done right. It can be a DIY if you are a good wrench. Or leave it to a professional if you are not. The actuator pads are under a tremendous amount of pressure when it is pushing on the chain to change the cam timing. The other chain guide pads are not under the same amount of tension and therefore do not wear out as much as the actuator pads. That also means your bank 2 actuator pads are likely worn out and could use replacement. Replacement of the pads involves removal of the whole actuator, cam shafts, valve cover on bank 2, so that is a lot of labor and basically doubles the job. Your budget will tell you what you should do. Good luck.

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Good information. Considering the amount of labor it takes to do this job, I would think it's the wisest move to replace the entire tensioner assembly on both banks. There is a guy on another forum that just replaced Bank 1 to "save money" and didn't fool with Bank 2. Now he has high deviations on Bank 2. He kicks himself for not doing the other side while the mechanic did the work because it would have been much cheaper overall. Always more expensive doing it right the second time.

They never have the time or money to do it right the first time. It amazes me how they can magically afford to do it a second time.

My shop had a look and said it’s fine to drive like this for a while, but recommended to replace both cam chains and guides in the near future just like Nutty said. The price they quoted with engine out was fairly reasonable as well, so that’s what I’m going to do.

The question in my mind is: What is "a while" ? A week? A month? 6 months? 'Til it breaks? If it's not right - just fix it! It's only going to get worse, til it breaks...

^^this is good advice from dporto. I think you've heard from us and now the mechanic on what needs to be done. I would put this on my top priority list for 2020. It's not going to be cheap and so you might need to make some serious decisions. The chain tensioner kits for the 5-chain engine, are $1200 each. I'm sure the chains are that much at $25 each, but labor for this job is going to add to the costs significantly. If they prefer to drop the engine, you might want to consider other preventive maintenance type jobs like replacing the clutch, flywheel, IMS bearing, AOS, coolant expansion tank, etc. I know that might seem overkill, but in the long run you'd thank me. At the least, get the timing chain tensioner assemblies replaced and you should be good to go.

Don�t worry, I�m planning to have this done next month. It�s just that I am going on a snowboarding trip to the Alps next week with the 996 and wanted to know whether this was OK. I�ll definitely consider reasonable �while you�re in there� things since they�re planning to drop the engine. IMS has been done and the clutch is fine. Definitely water pump since I can�t find anything about this in the history, and maybe also the coolant tank. There seems to be a small coolant leak anyway that I�d like to have fixed.

I can rent a car too cheaply to gamble on a broken timing chain.. Just sayin,, $400 a week on a standard car, less if I use a few points or shop around.. I rent a lot from Hertz and 35 to 50 a day is my average..

^^Not saying your suggestion isn't valid but by his license plate in the first post, it looks like he is in the Netherlands.

Ya he is in the Netherlands, however, I still would not take it to the Alps. But, hey it's not my car and it's only money.

I’m in the Netherlands indeed. I took the car to my shop (who do mainly watercooled Porsches), we did a test drive while looking at the data on the computer and they concluded that I don’t need to worry about it for now, so that’s what I’m going with. Of course I can rent something else but there’s no fun in that. Be assured that I will have it fixed within a month or two. I’ll report back with the cause because it might help someone else with a similar problem.

An update and a question... I did take my 996 to Austria and it was awesome! Between snowboarding I had some time to drive through the mountains which was just amazing. We made it back without a problem. Now the car is at my indy and they recommend replacing the chains, chain guides, Variocam actuators and solenoids, and that sounds good to me. Since they're pulling the engine, it's a good time to do some preventative maintenance work: AOS, water pump, spark plugs and coils (if needed). I'm also going to have them replace the injectors per Jake Raby's advice to possibly avoid bore scoring. So that's all good. They suggested that I could also choose to have the valve lifters replaced (intake and exhaust) which would add another $2500 to the (already hefty) bill. I couldn't find much about it and my gut feeling that this is taking it one step too far. After all, the engine could blow from one of the other 31 modes of failure (I forgot how many there are). What's the opinion here?

$2500 seems a lot when the engine is already stripped to the point you could just swap lifters in about 30 mins , with the valve covers and cams already coming of the lifters are just there open saying please change me !! That price sounds like they trying to double dip you for the labour ,lifters don't cost $2.5k unless you got the vario plus intake lifters which are loads but I don't think they have a bad rep for failure maybe others will chime in ?? I bet they already billing you a **** load for what you already having ! The cam deviation will just be the chain pads on the vario actuators they get hammered , maybe do the small chains in the head aswel if it's a five chain engine and the main chain ramps and tensioners, that should do it !

Just to add from your picture looks like an early rear bumper so five chain , all normal lifters , there's threads on here about sourcing OEM lifters , the same ones porsche use made by INA who make the original lifters in your car now for a few hundred dollars , I think I'm gonna come over to America and open a shop!!

They say it is just parts, they don't charge labor for this. Five chain 3.4 engine indeed. For all the Variocam work, including dropping the engine, new chains, new guides, new solenoids/actuators and seals, the price is around $3000 which seems reasonable. But I think they source all parts from Porsche which makes it more expensive than it needs to be.

Maybe you can source the lifters and get them to fit them ?

Most shops won't do that because if there is a problem afterwards, if's difficult to tell whether the parts were bad, or whether they did something wrong. So they want to use only parts that they have experience with, which I understand. I've decided to skip on the valve lifters for now. Thanks for the feedback!

When you get this engine all apart, you will find a little green o-ring inside the vario-cam actuator has failed. It causes the vario-cam actuator valve to not be sealed and cannot control the movement of the valve timing correctly. This is always interesting because the 50cent o-ring causes thousands of dollars of "while you're in there" repairs to also commence !!!

So true...

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Does Porsche sell this little green O-ring or do you have to replace the actuator?

Is that the o ring that fits under the actuator pad?

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Porsche does not list the o-ring, it comes inside the actuator. No, different o-ring, the one I'm referring to is internal to the actuator where the valve is.

PT3...is the actuator serviceable?

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Not according to Porsche, and I really haven't had time to try to service any, although I do have about half dozen in a box in the basement for a "rainy day"..

Would be interesting to open one up to see if in fact they are able to be cleaned and then refurbished. Could be an exercise in futility though. Thanks for the

I had mine apart when I did my rebuild and I've got the ones from my old engine in storage so could look at the o ring if needed!!

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If you remove the solenoid and valve/piston then look down the bore, you can see the little green o-ring (if still there). I haven't tried to remove/replace one, but I think it could be done.

I just realized I never got back to this topic. In March 2020 my specialist has replaced the cam guides, chains, solenoids, actuators and a bunch of "while you're in there" stuff like lifters, new injectors, coils, plugs, water pump and thermostat. Since then it has been running flawlessly. My cam deviation values are less than 0.5 degrees on both banks and the check engine light has never come up again. It wasn't cheap but I guess this was all kind of normal maintenance after 60k miles. On to the next 60k! :-) Thanks for all the advice in this thread!