[E46-Cabrio]

Yes, you can remove and install the double vanos on a M54 engine without screwing up the timing, they are two different рдят5.

[lustek]

Added one more oscilloscope capture with all 3 sensors simultaneously at 20ms/div:

CH1 (pink, top) → crankshaft (CKP) – dense regular pattern as expected
CH2 (cyan, bottom) → intake cam (CMP)
CH3 (yellow, bottom) → exhaust cam (CMP)

Both cam sensors show clean rectangular signals with different pulse widths relative to each other. All 3 sensors are alive. Can anyone confirm if the phase relationship between the cam signals looks correct for M54B30, or does it suggest a timing issue?

Bumping this thread – could anyone with M54B30 experience take a look at the oscilloscope screenshots I attached?

I'm specifically wondering:
1. Do the cam sensor waveforms (intake and exhaust) look correct for this engine?
2. Does the phase relationship between the cam signals and the crank signal look normal, or does anything suggest a cam timing issue?

At this point I'm also unsure whether to focus on the cam timing (possible tooth off during VANOS reassembly without locking tools) or whether the DME itself could be the root cause – stuck in a fallback mode and refusing to output PWM regardless of sensor inputs.

Any input would be greatly appreciated, even just confirming whether the patterns look right or wrong.

[Node]

Why won't you use i5тд to check engine timing? I don't remember about M54, but M62 definitely had operating values check which timing check was рдят of. Anyway it's been ages since I worked on any of these. But when I used it AFAIR it immediately found that one of cams had wrong timing preventing VANOS operation. And I also had sprocket dismantled from the cam. Even I had tool to lock the engine I did not have special chain tensioner and that was enough to get wrong timing!

[BSBBMW]

Well, your code clearly says exhaust camshaft sensor SIGNAL IMPLAUSIBLE. I have no idea how anyone can properly assemble BMW engines WITHOUT locking tools...

M54 you can do without tools , the timing is set by the рдят5 behind the vanos , just loose the two left turning bolts and take of the vanos , very simple and i did a few hunderd this way and never a problem .

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Hi everyone,

I'm working on a BMW E46 with the M54B30 engine (Double VANOS, single housing). I've been diagnosing this for a few days and I'm stuck – hoping someone with hands-on experience can point me in the right direction.

The problem:
Both VANOS units are completely inactive. Values in INPA are frozen – intake shows approximately +206° and exhaust approximately −105° – and neither changes at any RPM, including when blipping the throttle. The only fault code stored is the exhaust camshaft position sensor (CMP).

What I've already done and checked:

• Exhaust CMP sensor – replaced with a known-good unit, fault returns immediately on startup
  
• Wiring harness to both solenoids and to both CMP sensors – fully checked, no breaks or shorts
  
• Solenoid self-test – when solenoid connectors are unplugged, open-load faults appear instantly, which suggests the solenoids and their drivers are functional
  
• Direct 12V battery test on one solenoid – plunger extends, solenoid is mechanically OK
  
• PWM signal check – connected a 12V test bulb (as a load) to the solenoid connector with the engine running. Bulb lights up immediately and stays at constant brightness regardless of throttle input. No flicker, no dimming. This tells me DME is outputting a steady DC voltage instead of a PWM signal – consistent with it having lost CMP feedback and going into a fallback/limp state
  
• Full VANOS disassembly – all O-rings and seals replaced, piston clearances corrected (there was significant play before the rebuild)
  
• Post-rebuild retest – no change. VANOS still frozen at the same values, same CMP exhaust fault
  

My questions:

1. Could the oil supply to the VANOS unit be the root cause? E.g. blocked oil gallery, faulty oil pressure control valve on the front of the engine, or low oil pressure overall? Could insufficient oil pressure prevent the mechanism from moving enough for the CMP signal to be valid?
   
2. Is there a way to verify VANOS oil supply pressure without specialist equipment?
   
3. Has anyone seen a case where the DME itself caused this – stuck in fallback, refusing to output PWM even with everything else correct?
   
4. Any other checks you would do before condemning the DME or pulling the front of the engine again?
   

Any help or experience with this specific failure pattern would be greatly appreciated.

Thank you.

Do you have any oil pressure at the vanos ? You can NOT test the solenoids with 12 volt , you kill them. First check oil pressure because if you have pressure the vanos should do something , second check the sensor ( cpm ). you can check oilpressure at the vanos by take out the pressurevalve at the vanos and see if enough oil comming out when starting the car .

[lustek]

Thanks for the response.

Regarding the CMP sensor – I already swapped it for a known-good unit and the fault came back immediately on startup, identical behaviour. So I'm fairly confident the sensor itself is not the issue.

On the oil pressure – that's exactly what I had in mind as the next step. I'll check it at the VANOS by removing the pressure valve and observing oil flow on startup as you suggested.

One additional question – could the oil pressure control valve located at the oil filter housing have any impact on VANOS oil supply? Could a faulty or stuck valve there cause insufficient pressure reaching the VANOS unit?

[BSBBMW]

Thanks for the response.

Regarding the CMP sensor – I already swapped it for a known-good unit and the fault came back immediately on startup, identical behaviour. So I'm fairly confident the sensor itself is not the issue.

On the oil pressure – that's exactly what I had in mind as the next step. I'll check it at the VANOS by removing the pressure valve and observing oil flow on startup as you suggested.

One additional question – could the oil pressure control valve located at the oil filter housing have any impact on VANOS oil supply? Could a faulty or stuck valve there cause insufficient pressure reaching the VANOS unit?

No , otherwise you should have also a bad oil pressure for the whole engine. This type of vanos works on the engine oil pressure because of the big pistons inside the vanos , the vanos for M enigines have there own oil pump inside to increase the oil pressure because this units use a smal piston so they need a higher pressure to move .

[Node]

I found this picture in BMW training for M54. This does not match your numbers so IDK.

[BSBBMW]

I found this picture in BMW training for M54. This does not match your numbers so IDK.

I think we already know the vanos is not working or not correctly

[Node]

But the picture provides actual numbers which should be in both default and max advanced/retarded positions. But they aren't.

[lustek]

Oil is flowing out, so there is oil pressure reaching the VANOS unit.

Honestly, I'm running out of ideas at this point