N55 Valvetonic 2DCF No movement identified
Vehicle originally came in with code: 2E0F Vavletronic system deactivated, adjustment fault too frequent. Customer reported it would occasionally lose power. This was confirmed with a test drive.
- Checked for power downstream of Valvetronic relay and fuse: OK
- Inspected harness between DME and valvetronic motor for open/short: OK
- Confirmed DME integration level was newer than 10-09-511 (currently 16-11-500)
- it appeared the the valvetronic motor had been replaced by the dealer or previous owner. (2 plug wells appeared to have been removed, injector lines and coils marked)
- oil pipe for valvetronic motor had been previously installed incorrectly... chewing the tip and damaging the teeth on the eccentric shaft. Valvetronic motor was worn and sticking.
- oil was black. Was informed it was last done by dealer at purchase 7 months previously.
- replaced eccentric shaft and valvetronic servomotor
- inspected cam lobes and secondary levers for excessive wear.
- performed valvetronic run in with snap on modis (1st run in failed due to some unspecified communication error, 2nd attempt was successful).
- Test drove vehicle at varied speeds and varied acceleration and appeared ok. no codes returned.
- synthetic oil change done
- recommended that customer do another oil change with full synthetic, after a short period. and to bring vehicle back if any codes return.
Vehicle returns after 700km with no start/cranks condition
- no start/cranks
- Code 2DCF No Movement Identified
- visual inspection confirms no servomotor movement,
- valvetronic relay and fuse outputing power. ISTA scan data confirms this.
- ISTA Details state "Current for VVT Motor is 0A"
- Servomotor pin 6 shows positive voltage with probe
- manual turning of servomotor seems smooth to me,
- eccentric angle data from ISTA shows 191.7 degrees.
- manually turning servomotor shaft shows no corresponding change in angle in ISTA when motor is NOT running. (not sure if this is expected)
While i have 8 years of experience. I am new to BMW diagnostics. While I HAVE repaired early 20xx BMWs before, this is my first N55.
At this point I am guessing that the DME had an intermittent problem and it has now failed ?
Replace DME, and then replace servomotor again ?
Possible to test DME output to servomotor ?
Thanks for any help or advice :)
Roy, Attempt to clear the VVT motor faults and run the VVT relearn function using ISTA. While attempting to run the relearn, measure your signals coming from the DME to the VVT motor. Its very possible that you lost a DME VVT motor driver. Do you have another vehicle with an N55 at the shop? Its possible to swap the DME from another vehicle and run the VVT relearn function to see if the…
Attempt to clear the VVT motor faults and run the VVT relearn function using ISTA. While attempting to run the relearn, measure your signals coming from the DME to the VVT motor. Its very possible that you lost a DME VVT motor driver. No movement seen at servomotor and scope shows no pulses on the 3 motor power wires.
Hey Roy I have run into two failed DMEs for no valvetronic current. You need to measure the voltage with a scope on all three phases. They must be equally phased apart too. Have seen one where they were all pulsed on at the exact same time, which won't turn any motor obviously, just vibrated. To check for binding, I have removed the sensor's gasket, and drilled a small hole through the valve…
To check for binding, I have removed the sensor's gasket, and drilled a small hole through the valve cover. Great idea. Did this and the engine started fine. Tried a spare servo motor connected without being installed and still no movement or pulses on scope.
I would think that you are on the right track. The DME which was failing, has now failed. I would clear the codes and try relearning it first as Nelson suggested. I think you will end up replacing the DME in the end though. Which leaves your question as to whether or not to replace the servomotor again. I would replace it again. Just to be safe. I recall reading somewhere that the drivers on the…
- I recall reading somewhere that the drivers on the DME for the valvetronic are a bit weak and they fail due excess current. While I am not certain that is true, it does sound reasonable. I have heard of a lot of these failing in this manner. Common issue based on what i have learned. A dealer tech warned me to order a DME as soon as he heard the situation. He said it was a common task. Local…
DME sent out for testing. Waiting on results. DME drivers on board replaced but still no change. Not sure if this was due to the auto electronics repair guy having less experience with BMW DMEs, or other problems. When testing I noted that ISTA didn't show any change in angle when manually turning a spare servomotor connected to the DME. This is was with engine both running (forced via hex key…
Resolved: Testing with a scope showed that valvetronic servo motor wasnt getting power. Even with new drivers. Customer took it back to where it was purchased and they installed/flashed a new DME. Valvetronic working now. I find it interesting that when the servomotor and shaft were replaced the DME was working. A dealership contact said that he had seen it happen. Often the DME fails…