While I can't completely rule out the fact that it could be a big issue, one major thing for me is that it doesn't appear to be from the major rotating assemblies. That is, when I turn the engine off I can hear the "noise" slowly running down and this continues almost unchanged beyond the point where the engine has stopped vibrating. I am confident that it if were physically linked to engine speed ie. crank, pistons, flywheel, camshafts or even something in the inlet tract then it would change proportionally as the engine speed changed.
Noise at 1350rpm
- Thread starter Kallaskalle
- Start date
Kallaskalle
Member
Same with mine. sounds wierd turning the engine off when the issue is present. The last sound from the engine is the wierd sound that appears in the videos fading out. Like a last 0.5 second long exhale
Zero likens to the “moovalve” sound.
Zero likens to the “moovalve” sound.
Yes, you're right - yours sounds quite drastic. Mine is barely noticeable - for the recording indeed I had to find a good spot.
Anyways, here's some inside information what mine does when it generates the odd sound.
What I think is worth to note at the moment of burst:
1. EGR valve is opened very briefly to allow exhaust recirculation (IDE07757 blue spikes).
2. The above halves fresh air intake (IDE00347 orange dips)
3. Turbo is commanded to boost (IDE00190 yellow spikes) - otherwise no boost (compare with normal idling on the right)
On the picture's right half where plots are "stable" engine has returned back to normal idling.
How about trying to stethoscope turbo?
Very interesting that so many components are playing a part. Possibly the control or feedback system on one of those components is sticking just enough to create a delay that is being constantly over corrected.
Thinking about it I have heard the turbo spooling up and down in time with the "noise" which tallies with your traces @mmi .
Thinking about it I have heard the turbo spooling up and down in time with the "noise" which tallies with your traces @mmi .
Kallaskalle
Member
Was in town friday when the sound begun once again, one of those days when it also is present in N or P.
stopped at Vw and they listened to it. They couldn’t tell but their best guess was maybe the flywheel in the generator.
The engine “jumped” and begun to sound normal after electric load (max fan, high beam on headlights)
They took some notes for the upcoming fail search
stopped at Vw and they listened to it. They couldn’t tell but their best guess was maybe the flywheel in the generator.
The engine “jumped” and begun to sound normal after electric load (max fan, high beam on headlights)
They took some notes for the upcoming fail search
That's also an interesting suggestion. Looking at random noises/failures a while ago I did come across alternator pulleys as a possibility. To my ears it could easily be a rattly pulley either on the alternator or the air-con compressor. However, I had dismissed this so perhaps I was too eager...
Kallaskalle
Member
Had the service at Vw the other day but no wierd noise that day of course so they couldn’t search for errors.
the sound appeared today again and I recorded it with a new phone (much better quality).
I also got the “coughing” on tape, after that the engine sounds good again and runs fine and I can’t trigger the sound anymore at 1300rpm.
The cough is 0:12-0:13 after that it runs fine.
the sound appeared today again and I recorded it with a new phone (much better quality).
I also got the “coughing” on tape, after that the engine sounds good again and runs fine and I can’t trigger the sound anymore at 1300rpm.
The cough is 0:12-0:13 after that it runs fine.
Kallaskalle
Member
No, the problem is still present. Every time it appears and I’m close to my nearest VW shop It disappear before I reach them.
Did you try to change N75 valve,I have similar problem on my T5 and seems to me that noise is connected with wastegate.
Kallaskalle
Member
No I have not. Will check it out, mine is early T6 with t5 engine so sounds interesting. Did u notice bad mileage/weak performance?
My T5 is driving well,only that stupid sound,and I am sure that sound is connected with exhaust(turbo charger,or Egr valve,turbo actuator,and that N75 valve wich is operating with boost of turbo charger)
Kallaskalle
Member
You have similar sound as me or the “moo” sound? I understand that m75 is often causing the “moo” sound which I never noticed on my vw
That sound on my T5 is exactly like yours,I’m driving that way for two years and I didn’t have any problems only that stupid sound.And it seems to me that sound coming from intake,you can hear it best when you open air filter box
Kallaskalle
Member
Yes, same with mine, i notice bad mileage on the live mileage meter display sometimes related to the sound. If the sound is present, restarting the engine solves the bad mileage and sound disappears.
Mine does that during regens, usually when I've released the throttle during parking or very slow speed driving. I've always thought it sounds like the compressor is stalling which I put down to the ecu switching on and off the post injection of fuel.
Kallaskalle
Member
One year on the road now, sound still present, maybe a little more frequent.
No breakdown yet.
No breakdown yet.
Kallaskalle
Member
Now the noise is present almost every time i drive. A quick restart solves the problem temporarily. Driven About 40.000km/25.000 miles with the Issue, the car Feels very dull sometimes for a 140hk diesel, and sometimes it feels more vital and lively. any new tips?
AnotherT5owner
New Member
Did anyone ever find out what this noise is? I've had the same noise for over a year, comes from the drivers side of the engine, hard to tell if its high level or low level.
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