Picture of a eccentric camshaft sensor on a N55 F10 2012 with about 50k miles,,,,check engine light on,,,,also noticed the engine didn’t idle to good,,,it had a rough idle,,,,also the power of the engine was low,,,,when the eccentric camshaft sensor goes bad,,,,the intake doesn’t know how much lift on the levers for the intake,,,,the sensor is magnet pick up sensor.
This is the major problem with this sensor,,,it starts to leak oil and the connector get wet with oil,,,,when it get wet with oil,,,,the due gets a fake signal from the eccentric sensor,,,,I have seen a couple times,,,the oil gets pumped into the harness and it goes to the DME connector,,,,you don’t want that,,,,it can damage the DME ,,,,if the oil gets inside the DME,,,,,sometimes we have to replace the small short harness form the eccentric sensor to the DME .
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bmwtechnician 
Hello bmwtechnician, I have a 3 series with a N51 motor. My car has a rough idle once in a while. This happens when I let the car idle in park for a long time, then when I put it in reverse the rpm would jump up and down and sound like it wants to stall. Like I said this happens once in a while, it only happens if I idle for a long time then put it in to reverse. If i put it back into park or neutral it will idle smoothly. Go to reverse again jump up and down. I replaced all 6 spark plugs and ignition coils. Cleaned VANOS solenoids with compressed air and MAF cleaner. Clean the MAF. It has been hard to diagnose because it only happens once in a while. Any ideas? Thanks.
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This is a hard one,,,,because like you said it only happens once and awhile,,,,,it sounds like you covered the basic stuff,,,,,check the eccentric camshaft connection make sure there is no oil in it,,,,,if there is some oil,,,,clean it out and see if the problem goes away,,,,,if it does then your problem is the eccentric camshaft sensor,,,,,,it possible that a fuel injector is going bad,,,,,,I hope this helps
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Now I notice something more. On top of the rough idle after idling for a long time and putting it in gear. In the mornings when I start the car cold, it cranks for a while. This happens on every cold morning start. When the car is warmed up it would start up quickly. Would the rough idle issue and the long crank when the car is cold be related?
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Any ideas to the mentioned above sir? Thanks!
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Yes it’s a good chance the two things are related
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Hello bmwtechnician. I have a 328i with a N51 engine. The idle jumps up and down and the car shakes when I put it into reverse. This happens on cold starts and when I let the car idle for a few minutes before putting it into reverse. This does not ever happen in Park or Neutral. Only in reverse and sometime drive. And only when I let the car sit for a few minutes when it is cold and then shift into gear. This goes away when the car warms up. I took a video of what is happening to describe it better. I would appreciate any advice or tips. I just replaced both VANOS solenoids and changed all 6 Ignition coils and spark plugs it did not fix the issue. Video: https://vid.me/Fdga Thank you so much!
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Thanks for the video,,,,,It sounds like a ignition coil is going out under a load on the engine,,,,but you said you already replaced the ignition coils,spark plugs and vanos solenoids,,,did you check and see if there is any oil in the connector of the eccentric shaft connector,,,if there is oil,,,clean it out and see if that helps,,,,it could be the eccentric shaft going bad,,,,but it’s hard to tell without the check engine light coming on,,,,,and it’s a tuff call to make,,,,,it sounds like you already took care of all the basic things that could go wrong,,,,you might have to wait until the check engines light comes on and faults,,,,I know that sucks,,,,but that might be the only way to find out what is wrong sometime.
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Thank you so much for your reply. I will take it apart and check the ecentric sensor for oil today. Also I noticed that when I unplug the MAF sensor, it seems to not idle as rough when I put it in gear. Would the MAF cause what is shown in the video? Again many thanks!
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The airflow meter could cause a problem,,,,,,can you check fuel pressure,,,,I wish we had some faults to work with,,,,there to many different things that can cause that problem.
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I just changed the MAF sensor too and the problem still seems to be there. So more things to add on top is a longer crank when the car is cold. Also when the computer calculates the gas mileage it is inaccurate. I get 1 more MPG than what the computer says I’m getting. Does this make you think of anything in particular with the added information? I appreciate your help.
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Can you check the fuel pressure,,,that can cause long crank
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I am going to check fuel pressure tomorrow. I notice that when the oil is below 180 degrees F the idle will sometimes be rough and jump in Reverse or Drive like the video I showed you. Once warmed up to 230 oil temp it idles better. Any ideas on what usually causes the car to idle like the video only when cold or not warmed up? Thank you so much.
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No there nothing unusual that comes to mind about the idle during cold start,,,,,compared to when the engine gets hot.
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Hello bmwtechnician. I just realized that I still have CPO warranty on my car until the end of the month. Is it also true that there is a 15 year 150,000 mile warranty on SULEV cars? However, if my car has been reported stolen will it void the warranty?
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That cool,,,,yes SULEV car are 15yr 150k on some thing,,,,,I don’t know if the car is still covered if stolen.,,,,I would think a report would come up when they do a key read on the car say the car was stolen maybe.
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Hello bmwtechnician, after all this time and money spend replacing parts and diagnosing I think we have figured out the problem! I finally got a chance to get a fuel pressure tester. So I hooked it up to the fuel rail and started the car. It stayed at a perfect 75 PSI. Then I turned the car off. I waited 10 minutes and looked at the gauge. It says 60 PSI. I am so glad you told me to check fuel pressure. So what is the problem here?
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That’s normal,,,,the fuel pressure should drop after 10 minutes,,,,,if it dropped all the way to zero then we would have a problem.
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I see. So it’s normal for it to drop after turning the car off. How about the video below? thank you so much!
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Yes it should drop off alittle and then hold pressure
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I tested the pressure again. This time when I start the car and test it, the fuel pressure gauge jumps around. The first time was was steady. Video of the second time. https://vid.me/7bCG Thanks.
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That’s interesting,,,,the gauge was bouncing all over the place,,,,keep the gauge on while the car is running and when the engine starts running funny,,,,see what happens to the fuel pressure,,,,see if the fuel pressure changes when the car starts to run bad.
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Okay i will do that. If it does what will that mean? Injectors or pump?
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Fuel pump
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If injector is bad,,,,you would see it on the spark plugs,,,,the spark plugs would be fuel soaked
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Ok. I am going to take this in as I have CPO warranty. But I like to work on cars so I want to know what’s wrong and diagnose it myself and learn before I take it in. As a technician yourself, do you advise me to tell them that I did the testing and tell them what I find or I should not tell them when I bring my car in? Thank you so much!
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I would let them diagnose the car.
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So the shop foreman and tech could not get the problem to replicate over 3 days. But it happens to me everyday! It idles better with the AC on and when it is warmer outside. Any ideas why?
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The only thing that comes to mind,,,,has anyone every raised the idle 100rpm and see if that helps,,,,I say that because you said that idles ok with the a/c on,,,,and I know the idle raises with the a/c on.
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Yes that is correct and that is what I was thinking too. It only idles rough when it is kind of cold and in Drive or Reverse. When it is warmed up it goes away, no fault codes. New coils, spark plugs, Vanos solenoids and MAF sensor. Just for some reason the idle wants to drop when I come to a stop and the car is cold. The idle drops then jumps back up. The idle is at 680 right now, do you think I should raise the idle still and if so raise it to what number? Thank you so much!
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You can not raise it anymore then 100rpm,,,,that would be to high,,,,I would put it 75rpm more when it’s in drive and reverse,,,,,you have to set it for each one ok.
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So I took it to my local dealer Kuni BMW on Monday because I still have CPO warranty. I rode with the shop foreman and I was able to show him the problem. However it seems like they might be having trouble diagnosing my idle because it only happens sometimes when cold. Usually how long does it take max to run all the tests they can for a rough idle? Have you guys ever replaced engines because of idles that could not be fixed? Just wondering. N51 engine. Thanks!
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I’m glad the shop foreman finally verified the rough idle problem,,,,no we have never replaced a engine over rough idle,,,,let me know what happen
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Yes I will definitely update you on what they check! Have you guys ever had a rough idle N51/N52 that could not be fixed? It seems like my problem is one of the rare and stranger ones.
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No not any I can think of,,,,,hopefully they find the problem
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My service advisor just called today. He told me the shop foreman said there is a TSB for a software update that might fix my issue. I don’t understand though, if the car ran fine with the software when new, then how can the software be the problem 60,000 miles later? Have you ever fixed a bad rough idle when cold with just a software update from your professional experience? Just wanted to share the news with you!
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Sometime the software gets corrupted and flashing the DME with new software can help,,,,,it can’t hurt your car will get the latest software,,,,,I have seen software update fix a lot of weird things,,,,hopefully this fixes the problem.
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Hello bmwtechnician.
I have a 2011 535i Xdrive F10 3.0L Twinturbo with a N55 engine. Every time before I start the car I hear about 3 second of rattle noise from the valvetronic servo engine. The rpm jumps up and down and the car shakes after cold starts for about 1 minute. I have no check engine light on. But I can read 2 code which comes back after I erase them.
Valvetronic servo motor position sensor, electrical malfunction
Code: 135808
Valvetronic servo motor position sensor, plausibility implausible signals to each other
Code: 135A08
I ran over a deer body and my car was in the BMW dealership for 3 months.
My car had no engine issue before I ran over a deer body.
At the BMW dealership they replaced front lights, front bumper, covers under the car, and turbo charger pressure converter because I had low boost code on the scanner. I got back my car after 3 months with this rattle noise, and oil started leaking from oil filter housing. I have 145.000KM in the car. So after they give back the car to me I realized soak oil dirt on the oil filter housing area, and oil soak dirt near by the coils, valvetronic servo engine. I thought the oil filter house gasket and the valvecover gasket bad. I only replaced the oil filter and coolant gasket. And I cleaned one small area near by the valvetronic servo motor to see if the oil is still leaking out near by the valvecover. I thought the valvecover gasket is went bad. But after 1000KM I checked that cleaned area, and that cleaned area was still clean. So I think that oil vapor from the oil filter house area just sedimented near by the coils area.
Funny because I had no oil leak nowhere, and no rattle noise from valvetronic servo engine before I ran over a deer body. Only this issues showed up after 3 months when they gave to back my car to me.
Oil soak dirt near by the valvetronic servo engine. But the connector is clean.
Do you think I have problem with the valvetronic servomotor position sensor?
Or I have problem with the valvetronic servo motor?
Or both?
What is that rattle noise?
Do I have to remove the valvecover to see check the sensor or or the valvetronic servo engine condition. Or I can figure out somehow without removing the valvecover?
I made small video about the noise. Here is the link:
https://vid.me/qUlO
Thant’s a lot for your help!
I appreciate.
Regards John.
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Sorry unable to play the video,,,,try and disconnect the valvetronic motor and start the engine and see if the noise goes away,,,,if it does your problem might be the valvetronic motor,,,,but I have seen both of them going bad at the same time,,,,when the car sat for months could have caused a problem,,,,sometime when these engines sit for awhile some of the electric motor get frozen and cause more problems.
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Thanks bmw535blog for posting that video. I am going through the same issue with my N20 engine. Dealer wants to replace the eccentric shaft also. I am really torn on approving that because I had the car not start, then start and go only 10 mph, then not start, then start and run great (should have gone somewhere else than the grocery store), and now won’t start/ rough idle when it does start. It has been sitting at the dealers for a week now. Because the problem comes and goes leads me to believe it is an electronic issue and not mechanical. Anyways, I have the same rattle in start up.
Thanx
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Hi bmwtechnician, Thanks a lot for your Help!
I try before just disconnected the valvetronic motor electrical cable, and I just unlocked the car, and does not make noise. But I did not try to start the car with disconnected valvetronic motor electrical cable, because I was not sure If I doing something wrong or not. So basically no noise if the valvetronic motor electrical cable is disconnected.
This is the N55 engine. So the Valvetronic servo motor has the sensor build in the servo motor. With the N54 engine the sensor is separate located front of the engine area under the valvecover. I was just wanna make sure no any other sensor freaking out which is outside of the valvecover. and easier to replace it. Do you think it’s only way to see what is wrong with the valvetronic servo engine is remove the valvecover and replace the servo motor? Because the sensor is built in the valvetronic motor anyway.
Valvetronic servo motor position sensor, electrical malfunction
Code: 135808
Valvetronic servo motor position sensor, plausibility implausible signals to each other
Code: 135A08
To me work this link If I click on it: https://vid.me/qUlO
Can I send this video to your e-mail address?
Thant’s a lot for your help!
I appreciate.
Regards John.
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Sorry video will not play,,,,,sound like you have a valvetronic motor issue,,,,yes on the N55 it’s all under the valve cover,,,on a N54 its on top easy to get to.
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Sounds like yes. I am gonna take off the valvecover to see why I have that rattle noise every time before I start the car. Sounds like try to calibrate it self every time before start but, some reason make this noise.
I upload on youtube this video. You will able to watch it now.
Thanks, John.
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Sounds like the valvetronic motor is bad,,,also check the eccentric shaft,,,,I had the same thing every time the valvetronic motor passed the test but it still failed
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Thank you! I will see soon.
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Does the eccentric shaft need replacing often when replacing a valvetronic (3, I think) servo? I have the same noise and plausibility code.
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Some time when we go though the test plan it will tell us to replace the eccentric shaft and valvetronic at the same time
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Thanks for taking time to respond, I went ahead and approved the repairs today with my service advisor. Also got a call from a BMW NA case manager stating that a decision should come within a week about my eligibility for any assistance in relation to this repair. Not really holding my breath, 57,000 miles on an N20 and second owner non CPO. $3500 which includes 2 hours of diagnosis. Let you know how it goes.
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Your picture shows a N51 or N52 motor. On the N55 the valvetronic motor and position sensor are integrated together, and mounted between cylinders 3 and 4, but you probably already know that, just pointing out the misprint for others who may get confused.
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Hello, I have a problem. Oil https://www.youtube.com/watch?v=hSaaq_0W2z4&t=2s
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Thanks for the video,,,,that’s the eccentric shaft motor going bad and trying to reset.,,,it also possible that the eccentric shaft is also going bad and is binding up.
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