Knocking/fluttering/ticking sound when accelerating

[LG99]

Hello everyone,

I’m hoping I can get some advice on this issue, been happening for a while now. A4 65 2.0 TDI quattro S tronic, currently at 71,000. 
 

when accelerating usually between 3rd and 5th gear there is a knocking/fluttering noise coming from the engine. Tends to be worse going up hill. 
 

I initially thought it was the octane rating, switched to v-power, did not solve, I use arch oil in every tank which helps but not solved. 
 

cam belt is due a change, could this be the issue? I’m hoping it’s not an issue with injectors?

a strange thing I have noticed is the car is brilliant to drive when it is doing a regen, no noise when accelerating, car is smooth to drive feels like new. I assume this from the extra diesel being used which is making me think there is an issue with the fuel injection or ratio which could cause the knocking on acceleration. 
 

any help would be appreciated!

[Stevey Y]

On 5/16/2024 at 7:17 PM, LG99 said:

Hello everyone,

I’m hoping I can get some advice on this issue, been happening for a while now. A4 65 2.0 TDI quattro S tronic, currently at 71,000. 
 

when accelerating usually between 3rd and 5th gear there is a knocking/fluttering noise coming from the engine. Tends to be worse going up hill. 
 

I initially thought it was the octane rating, switched to v-power, did not solve, I use arch oil in every tank which helps but not solved. 
 

cam belt is due a change, could this be the issue? I’m hoping it’s not an issue with injectors?

a strange thing I have noticed is the car is brilliant to drive when it is doing a regen, no noise when accelerating, car is smooth to drive feels like new. I assume this from the extra diesel being used which is making me think there is an issue with the fuel injection or ratio which could cause the knocking on acceleration. 
 

any help would be appreciated!

Hi the car runs better during a regen as the EGR is shut off [no exhaust gas] they all do, I would recommend a full diagnostic scan before condemning anything.

Steve.

[LG99]

Hello Stevey

Thanks for the reply, my apologies for the late response. 
Makes sense regarding the EGR when doing a regen. I still have the noise very annoying. Since the noise stops when doing the regen this makes me think that there could be an issue with the fuel trims, injectors or something related.
I have OBDeleven, no faults on the engine scan. I had the EGR cooler and valve replaced earlier this year but the noise also happened before this.

could it be the S tronic unit? It’s booked in for a service next week. Cam belt also needs changing soon.