Eliminate diesel clatter CDUC, CDUD 3.0tdi

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Leighspain1975

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Hi All
Thought I’d share this with you in case it helps someone......
Has any 3.0tdi CDUC, CDUD owners who have higher mileage engines notice a more pronounced diesel clatter noise at idle or at low rpm and maybe notice the engine isn’t quite as smooth in low rpm as it used to be ?.
Here may be your solution?.

I was desperate to find the solution to this issue and did everything, new injectors, Maf, egr and Dpf cleaning. None of these really worked and it annoyed me that such a nice engine wasn’t as refined as it should be.

By pure fluke I found the answer in 2 words “Swirl Flap”.....

Bear in mind that the older 3.0tdi engines has swirl flaps in the intake manifold. The 2nd gen engines don’t. It has one large motorised swirl flap before the manifold with two holes. One for EGR return and other for fresh air. The fresh air hole has a butterfly valve which opens and closes but mainly it’s a low rpm when it’s used to swirl the air into the intake.
These things fail and can do so without any warning light or error codes. The flap which gets built up with carbon may not be opening properly literally starving the engine of fresh air and too much EGR gases.

Quick solution is remove the part and remove the butterfly valve, it’s only two screws and the rod can be left in situ so no error codes are thrown when plugged back in.

Before removing the butterfly valve you can make a quick test. Unlock car open the bonnet, close the door and lock the car. Leave for a minute and disconnect the sensor/motor. The flap will now be fully open and you can test for yourselves if it improves the drivability of the car. It will eventually throw an error code and your Dpf may not regen as a result so if it’s improved I would suggest you remove the butterfly valve.

You may notice at first that the car pulls away a bit more sluggish than normal but the ecu will rectify this after a few 100kms.

The second part was to connect VCDS....
Go to Engine - Adaptation - EGR Correction

Select 35 mg/stroke as new value. Old value should be 0mg/stroke. This will close the EGR valve more and effectively tells the Maf to read higher fresh air intake you will probably see around 350mg/ stroke at idle with this adaptation. It’s within the parameters of the ECU so no harm will be done.

Guys give it a try if you think your engine is sounding a bit clattery.
Would be good to get some feedback if you try this yourselves.

Cheers
 
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I will try this weekend :) My CDUC behaves kinda clattery in cold weather these days, in low RPM and kinda low demands of power. I will report :) First I thought it could be bad DMF, but I have not found a single thread about anyone having a DMF worn out on these newer 3.0 TDIs, mine is only around 70k miles… And this actually makes sense.
 
Yeah,
Mines be fine since. Wouldn’t say any increase in power but the engine definitely sounds more refined.
Remember when you do it.... the butterfly will naturally be half open when the engine is off and you can’t get to the screws.
Disconnect first and then plug in and switch on ignition. The butterfly will move to a closed position and you can then get to the screws.
Don’t force the butterfly.

Cheers
 
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IMG 5753


Hi,

I will ask additional questions, I am not native so I need to make sure I understood your description. In the attached Picture - is the description ok? Is the part on the left the motorised swirl flap thing? If so, to test it, I should disconnect the connector on the side of it? If so, I would like to first test it out. So the procedure should be - unlock the car, open the bonnet, close doors, lock the car, wait a few minutes, disconnect the connector on the side of swirl flap housing, start the car and try out? What does not make sense, since you mention the natural position is half open, how can it fully open when disconnected?

If the test will be ok, the ride improves, then I should remove the black tuby thing and unscrew the flap plate on two screws, let the rod there and connect the housing to the connector again?

Sorry again :)

Thank you,

DJ
 
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Exactly correct

Unlock car, open Bonnet ( Hood ) , close door, lock car, wait a few mins and the. Disconnect.

Remember.
Half open is actually fully open. The flap will rotate 90 degrees to fully open position. So the flap will be horizontal and letting full air into the car.

If you decide to remove completely you’ll need to do what I said before. But the testing is very easy to do first.

Let me know the results

Thanks
 
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Ah, fine. I thought half open means like 45 degrees. This explains everything.

This actually looks pretty damn easy.
 
Yeah it’s a piece of cake to try it out.

Drive the car a little while too to allow the fuel / air adjustments to take place too. It may start a little lazy but while suddenly pick up and run much better.

I also find the engine idles much better too. The engine sounds more happy.
 
Mine looked the same. Filthy and clogged but I think the motor in mine wasn’t opening properly either.
Amazing to think all this filth comes from the Egr return.

I have closed my EGR to minimal allowable settings.

Vcds UDS protocol ....

Select Engine, Adaptations, EGR Correction. Should be at 0.0mg reduced mine to -50mg
 
Makes you wonder why they bother with an air filter TBH when they are recirculating so much stuff back into the engine.
 
Why would mine better when the DPF is regenerating?.
I know it’s doing it because the fans switch on.
It’s such a big difference too the engine will run quieter, be more responsive and it’s so much smoother.

Can’t figure it out
 
Hi guys!

So I tested it out (disconnected the connector, drive around for like 40 miles), I did not notice any difference, so I decided to let it be. I did not even disassamble the intake to clean it, I felt like too lazy this weekend :D

But thank you for advice anyway!

DJ
 
Leighspain1975 said:
Hi All
Thought I’d share this with you in case it helps someone......
Has any 3.0tdi CDUC, CDUD owners who have higher mileage engines notice a more pronounced diesel clatter noise at idle or at low rpm and maybe notice the engine isn’t quite as smooth in low rpm as it used to be ?.
Here may be your solution?.

I was desperate to find the solution to this issue and did everything, new injectors, Maf, egr and Dpf cleaning. None of these really worked and it annoyed me that such a nice engine wasn’t as refined as it should be.

By pure fluke I found the answer in 2 words “Swirl Flap”.....

Bear in mind that the older 3.0tdi engines has swirl flaps in the intake manifold. The 2nd gen engines don’t. It has one large motorised swirl flap before the manifold with two holes. One for EGR return and other for fresh air. The fresh air hole has a butterfly valve which opens and closes but mainly it’s a low rpm when it’s used to swirl the air into the intake.
These things fail and can do so without any warning light or error codes. The flap which gets built up with carbon may not be opening properly literally starving the engine of fresh air and too much EGR gases.

Quick solution is remove the part and remove the butterfly valve, it’s only two screws and the rod can be left in situ so no error codes are thrown when plugged back in.

Before removing the butterfly valve you can make a quick test. Unlock car open the bonnet, close the door and lock the car. Leave for a minute and disconnect the sensor/motor. The flap will now be fully open and you can test for yourselves if it improves the drivability of the car. It will eventually throw an error code and your Dpf may not regen as a result so if it’s improved I would suggest you remove the butterfly valve.

You may notice at first that the car pulls away a bit more sluggish than normal but the ecu will rectify this after a few 100kms.

The second part was to connect VCDS....
Go to Engine - Adaptation - EGR Correction

Select 35 mg/stroke as new value. Old value should be 0mg/stroke. This will close the EGR valve more and effectively tells the Maf to read higher fresh air intake you will probably see around 350mg/ stroke at idle with this adaptation. It’s within the parameters of the ECU so no harm will be done.

Guys give it a try if you think your engine is sounding a bit clattery.
Would be good to get some feedback if you try this yourselves.

Cheers
Click to expand...


I know this is an old thread but wanted to say thanks for the info, this has made a night and day difference to my SQ, waiting for vag-com lead so I can dial out a bit of the egr sludge
 

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Thanks for reviving this thread Bobt!
Decided to give it a go over the weekend (seen as Audi spent over a year diagnosing clatter/flutter!)
Gave it a good clean and installed in the fully open position and unplugged. It almost sounded like a petrol!
Plugged back in and now runs like a tractor - albeit not as loud as before, so the clean has helped.

I will probably remove the flap/valve. Tempting to blank off EGR now that I've seen the rubbish going back through the engine....possible MOT problems with that I suppose....

52k on the clock - CVUA engine.
IMG 2423
 
My Pleasure it’s helped.

it just takes the edge of that clattery vag diésel sound and makes it a little smoother.

Dont- map out the EGR or put a blanking plate. I tried it with mine and it sounded awful and loss of power too.
The EGR does help when it’s working properly. But you can use vag to close it of slightly that also helps.

plus with yours, you’ve got active sound no ?.
I strongly suggest you get the Cete Automotive sound module. It sound awesome.
 
When you disconnect with the flap fully open it will try and compensate the Maf. Removing the flap and keeping connected will trick the ecu as it thinks it’s still there.
 
jetty said:
Thanks for reviving this thread Bobt!
Decided to give it a go over the weekend (seen as Audi spent over a year diagnosing clatter/flutter!)
Gave it a good clean and installed in the fully open position and unplugged. It almost sounded like a petrol!
Plugged back in and now runs like a tractor - albeit not as loud as before, so the clean has helped.

I will probably remove the flap/valve. Tempting to blank off EGR now that I've seen the rubbish going back through the engine....possible MOT problems with that I suppose....

52k on the clock - CVUA engine.
View attachment 203159
Click to expand...
Same as yours mine is so smooth with it disconnected but still has noise when connected, initially after cleaning it was very very quiet but has got more noisy. I think it has to be the flap motor not operating the butterfly correctly
 
Leighspain1975 said:
When you disconnect with the flap fully open it will try and compensate the Maf. Removing the flap and keeping connected will trick the ecu as it thinks it’s still there.
Click to expand...
Firstly thanks for the info
when disconnected engine is silent for a diesel but im still getting noise when connected after cleaning which has returned gradually after the clean so im going to remove the butterfly to see if that cures it. Do you think removing the butterfly will effect DPF regeneration or are they any other negative effects of doing this?
 
When you think about it this butterfly flap can cause a world of problems. The sensor is only working based on throttle position and it’s the last sensor before the intake manifold. The ecu has already calculated air and pressure through the Maf and boost sensor and if this is clogged up theirs not enough air but the ecu thinks it’s fine.

this is why I felt we were getting more clatter and it’s probably due to pinging.

do you notice the injectors pinging when accelerating and the windows open?. You can hear the sound pinging of buildings and walls.

however when the Dpf is regenerating you won’t notice it as much because the timing is slightly retarded and actually sounds smoother when regenerating.

just my two cents.
 
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I was looking at it today and was thinking the same, i went ahead and removed the flap and noise gone while plugged in ! yes i could hear the noise only at low RPM. Yes was quieter during regen and that does make sense why. Thanks again for your two cents im so pleased noise has gone, im still waiting for my VCDS lead to adjust the EGR im also going to look at catch can options
 
Just a quick question...

Are your injectors Loud?.
What I mean is when you drive with the window open can you hear the injectors rebounding off walls and buildings ?.
I had my injectors change a few months ago and it didn’t change the sound at all.
The weird thing is that when the car is regenerating the Dpf the injector knocking disappears.
I’m assuming this is probably due to timing being retarded slightly.
But the noise drives me nuts. Hope it’s not just me....
Audi and everyone else say it’s normal ..
 
I'm glad I stumbled on this thread as I've thought for a while my 2015 SQ5 has sounded rather more diesel like than I remember at low setting off rpm from time to time. It's actually started to annoy me.
I'll have a look at the valve tomorrow if I get chance.

Sent from my SM-N960F using Tapatalk
 
Leighspain1975 said:
Just a quick question...

Are your injectors Loud?.
What I mean is when you drive with the window open can you hear the injectors rebounding off walls and buildings ?.
I had my injectors change a few months ago and it didn’t change the sound at all.
The weird thing is that when the car is regenerating the Dpf the injector knocking disappears.
I’m assuming this is probably due to timing being retarded slightly.
But the noise drives me nuts. Hope it’s not just me....
Audi and everyone else say it’s normal ..
Click to expand...
I did have some injector noise which I sorted by replacing the copper seals,orings and stretch bolts, were your bolts replaced when your injectors were changed ? Were the injectors new or reconditioned.

Audi said my noise was normal on a health check obviously wasn't because it's sorted now. Are you sure it's an injector and not follower's ?
 
So I took the intake hose off this morning to be greeted with this
20200525 101340 copy 2268x3024

Not very pretty!
The cars done just over 37k and I thought I was going nad thinking the car was more rattly than I remember.
So I removed the EGR flap housing and gave it a good clean
20200525 103458 copy 2268x3024

First impressions are night and day different from a quick drive around the block and it's back to how I remembered.
I know its an old thread but cheers OP for the heads up:icon thumright:
 
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I'm going to check my A6 Bitdi. It runs fine but I do think it sound slightly more "dieselly" when I back it out of the garage. Just a quick question, did you have to fit a new gasket / seal, or could you just reuse the old ones?
 
I'm starting to think it's not just the build up causing the noise ! It's the butterfly motor which isn't operating
jbmercapple said:
I'm going to check my A6 Bitdi. It runs fine but I do think it sound slightly more "dieselly" when I back it out of the garage. Just a quick question, did you have to fit a new gasket / seal, or could you just reuse the old ones?
Click to expand...
Just clean old gasket and reuse, that's what I did and was fine
 
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Leighspain1975 said:
Mine looked the same. Filthy and clogged but I think the motor in mine wasn’t opening properly either.
Amazing to think all this filth comes from the Egr return.

I have closed my EGR to minimal allowable settings.

Vcds UDS protocol ....

Select Engine, Adaptations, EGR Correction. Should be at 0.0mg reduced mine to -50mg
Click to expand...
My Hex-V2 lead came today so I tried to do this but any change I try to do comes back with error (request out of range)! Can you tell me the method you used
 
Hi Bobt

is your Ecu running on can or UDS ?.
If it’s the older ecu their is another way to close the EGR.

If it’s UDS like mine you should go to. Engine, adaptations select EGR adjustment from the drop box.

you will see 0mg in the box.
You need to type anything from 0-50. 50
Is the max you can close the EGR.
 
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I just cleaned mine, refitted and left the coding as it is.
The car is rapid now, picks up far quicker and just keeps on going.
On top of that the clatter is gone!

I am running an MTM cantronic btw not a remap
 
Hi im a new member ( audi a7 )and have just found this thread , quite a coincidence i have started to remove my inlet just yesterday to clean the inlet gunk before fitting an oil catch can to minimise the pcv and soot combined mix and coke up the inlet, just as a matter of preventative maintenance.
my car has no noticable clatter or worries but like to run an engine inlet as clean as possible .

anyway its nice to hear positives from this maintenance

so my method was with obdeleven

strip off the plastic pipe
remove the egr metal pipe
decarbon and clean these parts along with the swirl and throttle actuator bodys

go to engine control modules
output test throttle valve sweeping full range open close ok
output test imrc (swirl flap motor) valve sweeping full range open/close ok

but i thought yeah lets disconnect the imrc when shut to remove the flap just to see how it runs without it
(as i also have a muffler delete i may experience a slight throatier note from low down ?)

but its left stripped for now and i will get back to put it together when my new egr pipe gasket arrives


anyway im intrigued also in the egr reduce and looked at that function seeing it at o mg/stroke
just before i mess with that i am looking to verify the figure to change it to as it gives from something from -256 to 256

OP says change to 35mg so ill try that when i get to it



Can revert all this back to original at later point anyway if i feel its not doing anything


my understanding is less egr etc equals better combustion and cleaner engine oil with lower acidity equals better life for timing chain and turbo etc
 

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Think I am going to do this tomorrow. I have a 2016 BiTDi with 57k on the clock and I can’t help but think it is much more clattery at low revs than it used to be. Think I will remove the housing and clean it and remove the butterfly at the same time.


Sent from my iPhone using Tapatalk
 
e4d44860c16c99ed4d461bd6d6843578.jpg

Just has a quick look at this. Whats the best method for getting the housing out as the 4th bolt on the swirl flap housing looks very difficult to access with an allen key. Do I need to undo the Jubilee Clip on the flexible pipe and then start undoing all the hex and allen bolts?


Sent from my iPhone using Tapatalk
 
Last edited:
-Ju- said:
So I took the intake hose off this morning to be greeted with this
View attachment 203509
Not very pretty!
The cars done just over 37k and I thought I was going nad thinking the car was more rattly than I remember.
So I removed the EGR flap housing and gave it a good clean
View attachment 203510
First impressions are night and day different from a quick drive around the block and it's back to how I remembered.
I know its an old thread but cheers OP for the heads up:icon thumright:
Click to expand...

Clog up so bad oven cleaner foam is really good at getting it off


Sent from my iPhone using Tapatalk
 
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Just did this on my 37k 2015 SQ5. I'd guess it was 50% clogged up. Surprised how soft and easy it was to clean off with a bit of carb cleaner and an old scraper. I wondered if the plastic inlet manifold was also affected? Has anyone gone the whole hog and checked this out as well?
 
mikeav6 said:
e4d44860c16c99ed4d461bd6d6843578.jpg

Just has a quick look at this. Whats the best method for getting the housing out as the 4th bolt on the swirl flap housing looks very difficult to access with an allen key. Do I need to undo the Jubilee Clip on the flexible pipe and then start undoing all the hex and allen bolts?


Sent from my iPhone using Tapatalk
Click to expand...
You'll need Torx bits to undo the bolts not Allen keys. Its very awkward to get at some of the bolts, especially the ones underneath the black pipe.
Well worth stuffing a rag underneath where you're working to catch dropped bits otherwise you'll spend hours trying to retrieve them from the bowels of the engine compartment...
 
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Just wondering if anyone has any tips on removing the black pipe to access the butterfly valve? I tried this afternoon and removed all the highlighted bolts and loosened the jubilee-style clip (not removed), but the thing wouldn't budge! Any help would be very much appreciated. Thanks! Simon.

Audi V6
 
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there is a locating peg on left at swirl flap motor mount, also underneat there is a bracket mount torx screw just on right of egr metal flange
 
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Yes as above, once the jubilee clip is moved out of the way you can get access to it down the right hand side.
Just to add the car sounds sooo much smoother and more responsive now, if it wasn't for this thread I'd never have known :icon thumright:
 
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