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Cam Position Sensor Implausible Signal???

14K views 23 replies 6 participants last post by  Zenfnmaster 
#1 ·
I need some help here. I was driving my 06 Jetta (1.9L TDI, DSG auto, Stage 1.5 Malone tune) the other day when, all of a sudden, it lost all power- limp mode, i assume. I pumped the accelerator pedal and got no response. Car just idled along. I pumped the foot feed, took it out and put it back in gear with limited success. It carried on like this off and on for 10-15 miles. I had a shop plug it in and he told me that it had a "Cam Position Sensor Implausible Signal" code. I limped it back to the house where it sits with the battery disconnected. I will order a new CPS, but I don't think that will solve the problem. Is there ANYONE out there with some insight to this??:confused:
 
#3 ·
Sadly, no. I assumed that the number would be on the receipt from having the shop scan it. I called later and asked for the number, but they couldn't, (or wouldn't) get it for me. To me, it seems like the car wouldn't run at all if the CPS signal was "implausible". It starts and idles fine, and when it decides to, it drives fine, so I'm thinking it has to be something more than the CPS...
 
#4 ·
I would try to get it scanned again and get the code number. If they were using a more generic scanner, the code description may not be accurate but the code number should be correct. An auto parts store should scan for free.
 
#5 ·
The thing of it is, is that I never got a CEL. I'm pretty sure that the generic readers at O'Reillys won't find a code without a CEL... I've got a CPS on order, so I'll change it when it gets here and hope that fixes it. Hard to believe that nobody else in a group this size has ever had anything like this happen to them. :confused::confused:
 
#6 ·
Well, got it over to O'Reillys this morning, the car acted up again just as I was getting there, plugged it into their code reader and nothing. Talked with the guy there and he thought it may be an issue with Throttle Position Sensor, which doesn't seem any more crazy than Cam Position Sensor, but I don't want to just start changing random parts in hopes of fixing the issue. Thankfully, the car acted mostly normal getting back to the house, but still can't trust it. :screwy:
 
#7 ·
Has anyone else got any idea as to what else may be going on?? I thought there may possibly be an issue with the transmission that keeps kicking it into a limp mode situation... just a thought... still waiting for the CPS to show up, maybe thinking about it too much, but if anyone has any ideas, please feel free to offer up
 
#8 ·
Changed out the CPS today... took about half an hour - shop quoted 3.5hrs... :mad: Car still does the same thing, just as I suspected it would. I can't believe that nobody here has ever seen this... :confused::confused: Now I guess throttle position sensor would be the next suspect?? Anyone??:confused::confused:
 
#10 ·
I've gotten some responses at the other site, but still can't figure this thing out... seems to be a fueling issue- like maybe getting intermittent low fuel pressure. Can an injection pump go bad like that? Lift pump?? I replaced fuel filter, air filter, oil change less than2k ago. Timing belt has less than 10k on it and is less than 2 years old. Everything should be right with this car, but it keeps stumbling on me with no rhyme nor reason... ANYONE??
 
#11 · (Edited)
With the TDIs, it's all about the ECU measurement blocks. You really need VCDS to know what's happening. I have a 06 TDI. Without VCDS, it was a crap shoot of replacing parts. tried to maintain it that way and gave up, bought the darn VCDS reader. If you dont have it, try to find someone nearby who does.

It is possible it could be the wiring harness from the camshaft sensor to the ECU. It could also be the timing as the 06 TDI has an adjustable cam sprocket. Again, VCDS will tell you that though some other readers will read the torsion value as it is called. VCDS will also tell you what your injectors are doing so you can rule out fuel flow - which I doubt is the issue given your description.

If you have a malone tune, you should be able to get logs iirc.
 
#12 ·
I suggest that you spend the money and get a good diagnosis. If you think about it, the way you are going about this is a waste of your time and money.

Everything about a car revolves around a control unit /computer. When you want to go, you ask the computer to do that [throttle sensor]. If the computer thinks all is well, then it will go. If it does not like something, it probably will not. Depending on the issue and the software programmer, you may go into a limp home mode so you can get home or it will just sit there at idle.

Like I tell all my clients, nobody care about you. Your car sure does not. It is programmed to care about a few sensors and when the sensors are not friendly, the engine will not work right. So spend your time making the computer happy and it will return the favor with a good running car.

That is why you need to spend the money to have someone that understands your car and how the system works. If you do find the right person, it will be money well spent.

I've never understood why people think the parts person knows how to fix cars. Their specialty is to look up parts. Usually the mechanic knows how to fix them.
 
#13 ·
I appreciate the wisdom, and, yes, I totally agree that getting the proper diagnosis is the key to fixing my problem. I only spent $10 on the CPS, had it cost more, I probably would have asked more questions and dug deeper in the first place. I had little faith that changing it would do the trick, but for $10? Why not? That said, the codes that were pulled off it by pdan and his VCDS were P0341 and P0642. I have been reading up on possible causes and trying to figure this out properly. If anyone out there has any insight, I'm all ears. Thank you
 
#15 ·
$.02 more added.

For that sensor to work, you need power and ground. So I suspect you have three wires. Usually [but not always] the outer two wires are power and ground and the inner wire sends the signal back to the ECU. Usually the power wire is supplied by the ECU. It may work on 5V. So, with the sensor plugged in, see what the voltage is. If you have none, then you have something to start checking. Don't forget to test the ground. Then check the signal wire from the sensor to the ECU.

I feel you have a timing issue and the ECU is indicating that. The definition of the code indicates it's an implausible signal. That tells me that the signal is OK, but it's not at the right time. Therefore, the cam timing is off. If the cam sensor was unplugged, you would get a different code. Don't believe me? Unplug the cam sensor when the engine is running and see what additional codes you will get.

So, test the sensor, make certain it's working. I believe it will be and if it is, you got a timing issue. You need to get that right.

You may be ok to waste $10, but if I had that attitude with my clients, I would be out of work. Rarely is there a part cheap enough to throw at it without some type of test. There are tests that take a lot of time and since time is money, replacing the part may be the cheapest route. Shot gunning parts is a terrible habit to start.
 
#16 ·
Just so that we are clear, Butcher, I am not advocating the "shotgun" approach to fixing the problem. As stated before, I doubted the problem being the sensor in the first place(read previous posts). Was quoted $500 on top of being charged $100 for the scan, which had me pissed off from the start. I appreciate your wisdom(see previous posts), but I do not appreciate being berated for attempting to fix the car myself. I am asking for help with an issue that is a mystery to me, and if you yourself can explain to me as to why the car starts and drives like normal for awhile before, all of a sudden deciding to shut down and go into this "limp" mode, please do, because it idles and drives as smooth as can be, and even idles smooth when it decides to ignore the foot feed... Thanks again for your $0.02..:)
 
#17 ·
I believe I mentioned that the computer is upset and it throws a code indicating why it is. I mentioned that I do not believe it's a sensor because the description of the code indicates that the sensor is working but has an implausible value. I mentioned that there is a test for that sensor and you should perform that test and compare it to what should be there. If the values are there, then you should scope test the cam sensor and crank sensor to see if the signals are where they should be. Most DIYer's do not have a scope. Either way, you need to make the computer happy again.

If you have not done that, then I would highly recommend to get that fixed. Once that is fixed, then see what happens. In a perfect world, your problem will be fixed once the computer is happy.

If I could tell you why you have the problem while sitting on my couch drinking my morning coffee, I would be the richest person in the world. I only know that without testing you cannot figure out the problem. I say shot gun because that is exactly what we call it in my profession. Sorry if you are offended, I did mention that time is money and if it takes 2 hours to make a test and it takes 2 minutes and $10 for the part, yes, load up the shot gun.

I do not feel I'm berating you and I'm sorry that you feel I am. I'm just trying to gather the facts so I can understand what you've been thru. If my account of what you went thru is wrong, please point that out.

So, to wrap this up. Make the computer happy. Fix this cam timing issue first. Until you fix this issue, you cannot move on to the next step. I would stop asking yourself how can it be and accept that it is. Once you do that, you can move on. There is a diagnostic tree for most anything. You cannot start at the beginning and jump to where ever you want on the tree.
 
#18 ·
...so what you are saying, is that the camshaft timing may have somehow gotten out of whack, making the computer unhappy with the readings it is getting from the cam position sensor? While I am unsure how this may have happened, I will try and find someone with VCDS to stop by and help me adjust the timing(if that is what we find) before moving on to "shotgunning" any more parts;) Does this have your blessing? :peace:
 
#19 ·
The tests will prove where you need to go. The little information you have provided sure points to that issue [cam timing]. I do not believe the wiring has been checked or the actual signal.

IF everything tests ok, then the computer has failed. This is highly unlikely and many times the worst place to be for a mechanic. You have no way of testing the computer. You are not the person who programmed the computer. The only proof you have is there is nothing else wrong. If you do your testing correctly, then the computer is the only answer. I've been fortunate that when it comes time to replace the computer, I'm right. I always look at the fact that computer never go bad so everything is double/triple checked and ask myself what am I missing. Lots of hours lost and cannot be billed for.

I hope you get what I'm trying to say. Testing is where it is at. By performing tests, you get a better idea what you are doing. You get to understand better what the computer is doing. Shot gunning parts may fix your problem but the only experience you have is just throw parts at it. Ive worked with or hired hundreds of technicians. Most are no better than parts replacers. People are not bringing in their cars for shot gun repairs. Most people I know do not want to waste money on parts they do not need. $10 may be cheap for you and that is ok, but let's not sugar coat it, it called shot gunning in my business. I've done it too and most of the time I win. Not because I guess right, but I've done those tests for years and I know what fails better than most.

In my experience, implausibility codes are telling me the sensor is working but at the wrong time. Shorted to power means there is no ground. Shorted to ground means there is no power.

My shot gun is much more accurate than most and if I'm wrong, the part comes out and the client does not pay for my time. If it is a new issue, 100% of the time, testing comes first.
 
#20 ·
Camshaft timing is controlled by the cam sprocket which is adjustable. It is possible it spun. So that is a very reasonable "somehow" to how the timing got out of whack, there are others. You can tell by visual inspection, pull the cover, look at the sprocket, there is a window with teeth in the sprocket and a hole behind it, the hole should be roughly in the middle of the window. If not, it has likely spun. Hope you found someone with VCDS to get exact measurements.
 
#21 ·
Had someone stop by with VCDS yesterday and we tinkered with camshaft timing for a few hours... nothing seemed to do the trick. First test showed timing at -3.4, so we adjusted it and got to -1.0. Car was rough starting and continued to stumble when we test drove it. We tried several different timing settings ranging from -2.2 to +2.5 and nothing seemed to do the trick. He had to pack up and leave, so I replaced the original CPS, buttoned everything up, tried driving it again, with same result... Went inside, bit the bullet, and ordered VCDS for myself... Once it shows up, I'm sure I'll have many more questions for you all :wave: Thanks
 
#22 ·
i am having similar issue. can you rev your car in neutral to what? my issue just showed up. Drove car and no problems, Next day it started stumbling. New turbo so I adjusted rod thinking boost issue. No help, Stumbles around 2300 RPMS Won't rev much above 4K. I have a spare parts car and swapped a few sensors, no change. Am thinking cam sensor because my trans sometimes does not shift like it should. But also I hear a slight boost leak today for the first time. I do have a bootleg vcds and still not enough info from it. Did have the cam sensor implausible also.
Just noticed this was 6months ago did you ever get yours resolved?
 
#24 ·
I had a similar issue. As it turns out my car had jumped timing, and very soon after my timing belt broke, turning the car into a paperweight with wheels.
Take it to someone who knows VW's. Even good mechanic shops have trouble with VWs unless they either specialize in Germman autos or have a VW guy employed.
 
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