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Bought a 33k miles 2015 Macan S diesel recently from Porsche main agent and not happy with engine sound at low engine speed, around 1000-1500 rpm. Occurs under light throttle conditions and typically when driving on low throttle around town. Tapping goes off when speed increased and engine is then very smooth. Tapping is very regular and metallic. . Wondering whether tappets, fuel pump or engine injection perhaps over advanced. Porsche main agent says this is normal for Macans but, if so, I'm very disappointed with the engine. I'm not convinced though I drove a 40k miles 2016 model at main agent's for comparison and it also had a hard 'diesel knock' over same range. I find this sound very disconcerting and wondered if anyone could comment on this phenomenon please. Car is based in UK and therefore not prone to the well known Bosch CP4.2 pump failures in the USA caused by low sulphur diesel. . I run on top grade fuel but cannot say what previous owners have used.

Views welcomed
 

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So, to clarify, your diesel sounds like a diesel? Or is this something else?
 

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So, to clarify, your diesel sounds like a diesel? Or is this something else?
I attach a sound waveform for info. 'Spikes' (the tapping) in waveform occur every other revolution of the engine, making me suspect one side of the two-piston HP fuel pump. Knock goes away for a few seconds and engine is quiet as modern piezo-electric injectors are relatively silent these days. 3-Litre Audi V6 diesels, as fitted to Macan S are quite refined and, in my opinion, run very quietly. My question for the forum is simply to ask members if this sound is typical of their own diesel models. Have audio clip but can't seem to upload it to website. Can anyone advise on format/extension needed to upload it?
 

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Not sure if it is the same on a petrol engine, but had a tappet like sound on my GTS. it sounded exactly like too much clearance on a tappet in an older engine. The dealer swapped out the high pressure fuel pump and now she’s much quieter.

Could not hear it inside the cabin, but outside it was quite noticeable (and worrisome it was so loud).
 
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Very helpful comment RJE and adds to my view that it could be the HP fuel pump which (as it works like a tappet insofar as it is cam driven and moves a piston via an intermediate roller) could explain why it may tap when the loading is light, then quieten as it gets some load on it when revs/load increased. Hope I can get some advice on loading the audio clip. I also agree with you that the sound may go unnoticed by some from inside the cab but is quite evident when outside and bonnet raised. Many thanks for feedback.
 

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I should add too that the first 3 or 4 times it was in to the dealer for this item they said it was normal. Persistent pestering paid off.
 
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Swap out the HP fuel pump and see what happens. Could also be a noisy injector, if the fuel filter has anything in it something could have made its way to an injector.
 
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I should add too that the first 3 or 4 times it was in to the dealer for this item they said it was normal. Persistent pestering paid off.
I can understand that RJE - I'm good at persistent pestering! Thanks
 

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Swap out the HP fuel pump and see what happens. Could also be a noisy injector, if the fuel filter has anything in it something could have made its way to an injector.
I'm targeting the fuel pump, but it's expensive and a fair bit of labour so currently pulling facts together and checking experience with other Macan owners before re-approaching Porsche main agent. Car has Porsche extended warranty. Re your last point, sound at each injector is fairly similar and noise comes more from HP Pump area at back of engine within the V. Thanks
 

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I'm targeting the fuel pump, but it's expensive and a fair bit of labour so currently pulling facts together and checking experience with other Macan owners before re-approaching Porsche main agent. Car has Porsche extended warranty. Re your last point, sound at each injector is fairly similar and noise comes more from HP Pump area at back of engine within the V. Thanks
Roger that, sounds like you got a handle on it. Too bad it's not an easy swap like on my old Cummins!
 

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You're right! Not so much fresh air around the engine as with the 'old Cummins' which you seem to affectionately remember! So important to avoid ripping things out until the picture fully firms up. Thanks.
 

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Discussion Starter #13 (Edited)
Fully agree with you, even a good Audi mechanic!. Trouble is finding them. My main Porsche dealer said they could hear the noise that I was referring to but didn't know what it was, and simply shrugged their shoulders and said all Macans sound the same. I had another issue recently when the Glow Plug indication came up during a motorway run. I lost power for a minute or two then was able to exit the motorway, pull over and restart the engine and the light did not reappear. Info panel said to contact Porsche, which I did, and simply got the reply 'sometimes this comes on when the DPF is regenerating'! End of discussion. Could not explain why the DPF should be regenerating after 200 miles of unrestricted motorway driving, nor why the DPF warning did not appear if it had been a genuine regeneration. Trouble with many main dealers is that they are geared up to selling cars and basic after-service only. However, I do have the car booked in for checking at a reputable Porsche independent but have to wait a further 2 weeks. Will post their findings...…..
 
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