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Brand new Q7 TDI 45 - intermittent noisy engine at low RPM

SlartiB

New member
Brand new Q7 TDI 45
I'm experiencing intermittent annoying engine noise in the rev range 1000 - 2000rpm, only when the engine has warmed up, and only when the engine is loaded. (doesn't happen in P, if I rev it). I usually notice it when going very slowly, with gentle throttle. As soon as it goes above 2000rpm, it becomes very quiet & refined.
The noise sounds like a "diesel rattle" - I know it IS a diesel, but I've driven another example, and I don't think it ever made this sound.
An independent mechanic thinks it could be normal - he thinks it's the DPF regeneration - is that plausible?
 
1k to 2k seems low for dpf regen. I'm not sure on the brand new models, but they didn't regen that often either..
If you had a scanner, then you could log to see it it was doing a regen and then collate that to the rough times you are gearing the noise.
Maybe ask the dealer if they can see how many times its happened to give you a rough idea (how many times can I say regen it one post??!!!)

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Yes I was wondering about the scanner - I have a dongle so maybe I can monitor it while I'm driving, too.
Re the regen, my understanding (from Googling) is that there are two types of regen - "active", and "passive". Passive occurs naturally (e.g on the freeway), whereas active is where it intentionally raises the exhaust temperature, by injecting more diesel. According to my mechanic, this makes the engine run a bit rough.
I'll be going for a test drive with Audi ASAP, in any case.
 
Nope - you're right jnrdavo - Audi said it won't be doing DPF regeneration in the conditions I'm describing, and that the symptoms do NOT sound normal. However, they also said the engine is super smart, and that it's probably nothing detrimental, and can wait for the first service. (any serious problem would be detected by the engine management)
 
As long as you have logged it with them, you are covered... Then again, you can always say that you are 'hearing' something else, and then book it in to get checked out. They need to make sure you are comfortable with the car, you are the client at the end of the day!
 
If its not happening during warmup and its in a low RPM bracket, if I was guessing id put it down to cam adjustment related or something with your timing or even fuel pump.
As I tell everyone, run it though a readiness code health check and if there is anything out of its parameters it will tell you.
Definitely check your engine oil though.


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FWIW, I've made a recording.
It's the "rattle" or "buzzing" sound that I object to. I don't mind the low frequency droning sound so much.
There is some rumbling coming through - that's just because the recording device was fixed to the vehicle (the centre console), so it gets directly coupled. (I enabled the low frequency cut function on the recorder, but some rumble still gets through)
Pay particular attention to these times:
0:00 (the beginning)
1:20
1:44
3:23
Link to recording (6MB MP3): https://drive.google.com/file/d/1KJfXCA0pfM27yFar3gEP40wDgMWIPKl9/view?usp=sharing

The dealer went for a test drive with me, and say the sound is normal.
 
Last edited:
Yes. I have complained twice, about that same noise, to be told is normal injector noise.:roll:
In my case 2020 SQ5 TDI, and likewise had VW diesel in2 litre form that only ever made a similar kind of noise at cold startup, so was surprised to have that noise in much more expensive vehicle from ultimately same company.
 
It's quietened down somewhat over time - I no longer have any complaints. It still gets a LITTLE bit noisy, but not enough to be an issue. My passengers frequently comment on how quiet it is for a diesel.
 
That's good news. They are way quieter than rhe old diesel cars!

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