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M54 VANOS Faults Have Me Stumped

13K views 23 replies 5 participants last post by  Oldmactech  
#1 ·
I have a long-running VANOS problem that has me stumped. I will, somewhat randomly, see various faults relating to the intake cam timing. By far the most common one is P0011. But, when I monitor real-time data, all looks fine - the "Reference" position is always at 119.x degrees, and the actual position is always within ~1 degree of the target position, all the way up to 5000 RPM.

I originally suspected there was something wrong with the way I timed it when I rebuilt the head last year, but if that was the case, it seems to me it would ALWAYS be throwing one or more faults. But, it will go sometimes a week or two with NO faults, then, typically, seems to throw a fault on a warm engine start.

I was just about to pull the valve cover and double-check the timing, but that now seems to me like a waste of time. Any ideas what I should do? Seems to me this may be some transient that occurs on engine start, which suggests perhaps it's related to oil pressure?

Regards,
Ray L.
 
#4 ·
Yes, but I did the timing using the proper fixture, and followed the procedure in the factory service manual to the letter, so I have a hard time believing it is really wrong. Besides, as I pointed out, it will go sometimes weeks without flagging a problem. That should not be possible if the timing is really off.

I'd really like to know what numbers others see for the ref position, and both expected and actual advance, perhaps at idle, 3000 RPM, and 5000RPM, just as a basis of comparison.

Regards,
Ray L.
 
#3 ·
I watched a video last week where it was suggested that the ECU can get confused about which sensor is causing the problem ie. reports intake when it is actually the exhaust sensor or crank sensor. Maybe you are chasing a red herring. I had an intake cam sensor DTC so I changed it. It still wasn't right so I replaced the exhaust sensor. Fixed the problem. So just change the exhaust sensor. See what happens.
 
#5 ·
Sure doesn't seem like a sensor problem to me. Both sensors are working, and reporting plausible values that are always within ~1 degree of the expected value, so I see no reason to suspect either is failing.

Regards,
Ray L.
 
#6 ·
I posed this question some time ago. There are 4 values for each camshaft. The Reference position, Specified position, Actual position and Flank adaptation. The question was : What do they actually mean? When you cite an inlet reference position of, say, +122 and an exhaust reference position of -105 then where is the datum line from which those angles are measured? I tried to figure that out.
I did come up with a theory but I won't go into it here. But I think you should be looking at the ACTUAL position and the Specified position. The two tend to be closelt aligned and generally different from the Reference position. So monitor the Actual values. They should fluctuate but not widely.
 
#8 ·
My assumption, perhaps incorrect, is the numbers are relative to TDC, which would make sense, based on this diagram:

https://www.bimmerfest.com/forums/attachment.php?attachmentid=498348&stc=1&d=1426773234

I would assume the reference position is the starting position, set by the static timing fixture, and when no oil pressure is applied. That position never changes, which would make sense. As for the specified and actual positions, they do change, and are always very close to each other, which tells me there is nothing really wrong with the way my VANOS is working. My guess is the reference position is my problem, which is why I am curious what other people see.

Regards,
Ray L.
 
#9 · (Edited)
I just found something I had not seen before. I've been using ODBFusion to read/reset codes for the most part. But today, since I wanted to see the real-time VANOS data, I got out my Foxwell scanner. The SES was on, and ODBFusion was reporting a P0011 (Intake CAM over-advanced or performance), but with the Foxwell, I get a "67", which it says is "VANOS end position not reached". Whatever this fault really is, it did disable VANOS entirely until I cleared it, and re-started the engine.

Are both referring to the same fault? I've never seen them disagree before...

Regards,
Ray L.
 
#13 · (Edited)
I am a little confused by your P0011 code. I can't find it on the list of official P type fault codes for the E46. But on one of my scanners, a BMW specific scanner, 67 is hexadecimal notation for the BMW fault code 103 (103 = decimal equivalent of hex 67) which is described as "VANOS faulty reference value intake". The P code for that is P1519.
 
#12 ·
I had the “Vanos end position not reached” error message after doing a vanos rebuild. Took it back apart and cleaned all the oil passages, went away. Might be tiny bit of debris (I was unable to find a clog)but that cleared it, never came back.




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#14 · (Edited)
This won't fix anything, but easy and worth a shot. Clear the DME adaptations. If there's a real problem the code will come back, but at least it resets the VANOS heuristic data. I've seen more than one case of funky DME behavior after a repair cleared out by that, especially on old original DME software.
 
#16 ·
That is an interesting thought. I have, in the past, seen P0012, which is the same fault, but for the exhaust cam. Have not see that one in many months.

Tomorrow I am going to pull the valve cover, have a look-see if I can find anything visually wrong. I don't expect to. I *think* I should be able to confirm timing is correct, even without the fixture, by visually checking the arrow on the exhaust cam is lined up with the gasket surface, the intake impulse wheel position, and that the splined hub positions are correct.

Regards,
Ray L.
 
#17 ·
Yup, the Peake tool also reports 67, which it decodes to the same thing as OBDFusion - Intake VANOS over-advanced or performance.

Is it possible it is unhappy with the VANOS performance, rather than the timing?

Regards,
Ray L.
 
#20 ·
Well, I finally got around to pulling the valve cover today, and what do you know? The computer is right - the intake cam timing is wrong. It is advanced by several degrees. What I can't understand is HOW?? I used the correct fixture to install the cams when I did the head rebuild, I followed the procedure in the factory service manual, and I re-verified after rotating the crank two full turns.

Tomorrow I will use Sapote's method, which does not require any special tools, and see if I can't set it right this time.

Regards,
Ray L.
 
#21 ·
Weird idea:
If the head gasket was done, possibly the wrong height gasket was used? If enough meat was removed from the head, the geometry of the chain length changes and over time it could cause the timing to wander off. I don’t remember the exact spec a replacement gasket would need to be thicker than stock to stretch the chain to proper height.










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#22 ·
Weird idea:
If the head gasket was done, possibly the wrong height gasket was used? If enough meat was removed from the head, the geometry of the chain length changes and over time it could cause the timing to wander off. I don’t remember the exact spec a replacement gasket would need to be thicker than stock to stretch the chain to proper height.
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Cam timing is set with the head securely bolted down, and the cam sprockets are fully adjustable. Head gasket thickness does not enter into the equation at all.

Regards,
Ray L.
 
#23 ·
As only the intake cam is off (the exhaust is exactly on spec), I wonder if I can cheat a bit, and loosen the bolt that secures the splined "shaft" to the cam, make sure the piston is fully forward, loosen the three nuts that secure the sprocket to the intake cam, re-position the intake cam properly, then re-tighten the three nuts, and finally install the splined shaft bolt.

Unless I'm missing something, this *should* restore proper timing, without having removeing the VANOS, and re-doing everything from scratch. As I said, the exhaust cam is set exactly right.

Regards,
Ray L.