Facelift FL Tick / Rattle

[c2wak]

Hi all,

Started a new thread now we know a bit more about this issue.
So as you know we have a metalic noise from the loose exhaust valve pivots. This is a given, Audi replace backboxes for this.
We have a cold start Tick / Rattle which can be hidded by starting in Dyamic or mapping it out and we know this is to do with the start up cycle and is normal.

For us with a Decat, we get the cold startup rattle / tick all the time. In a nutshell we have had custom decats, Miltek, Scorpion so we know its not them. We now have 3 different back boxes, Miltek, Scorpion, and Audi and they all still have this issue. But closer investigation shows this is coming from the front of the car. Alot of suspicions are the Wastegate.

So the noise is always there its just not aparent with a cat and the decat exhibits the noise, or does the change in pressure cause the noise?

What resolutions do we have so far:
1) Put original cat back on (thats just crap)
2) Try a sports cat? (expensive option)
3) Try and get Audi to look it as a fault? - They may just say - put the cat back on.

So completely ****** off with this car now. 56k and cant even stick a decat on it without it sounding like a bag of smashed hammers.

Rant over. Anyone else with any insight feel free!.

 

[Dan_DJT]

I feel that the noise you talk about will only go via a remap to change wastegate position. Be interesting to know if cars with remaps also have the same noise

It is annoying and does spoil the whole user experience a bit.

Sent from my ONEPLUS A5010 using Tapatalk

 

[c2wak]

Mines mapped Dan and it still does it. That being said, I dont know if its been changed as you mention it to change the wastegate position. Where did you get the information about the Wastegate position?

 

[c2wak]

Ah i think you mean what Aoon said in an ealier post about the cold start the Wastegate is fully closed, this isnt the cold start thats the issue. Same noise just all the time.

 

[Dan_DJT]

Yeah it was mentioned a while back on another post but I think the wastegate is fully open not closed. Fully open would allow gas to bypass the turbine straight into the cat to help with heating up the cat. That combined with retarded ignition and injection makes the loud noise. On my car the same noise is present when fully warm but not as loud, I hear it more when driving next to a wall etc. My view is that at part load low rev driving the wastegate is open as no or little boost is needed, and the noise is produced. At higher load but still low revs the noise is still there but as soon as the revs rise a little the turbo is called upon (and wastegate moved towards being closed) and the noise is replaced by the turbo as it spools up.

I imagine that some remaps may only focus on high load changes, I am sure that with the right resources the low load wastegate control could also be changed.

Obviously this is all just my opinion but is based on 20+yrs working in engine calibration development.

 

[Behind The Bins]

Are we talking about a constant ticking noise which can be heard at low speed?

I have this, standard non sports exhaust

 

[Dan_DJT]

Are we talking about a constant ticking noise which can be heard at low speed?

I have this, standard non sports exhaust

Yeah thats the one, sports exhaust does it too

Sent from my ONEPLUS A5010 using Tapatalk

 

[Behind The Bins]

Any fix? It can be annoying

I suppose it’s pointless booking it in with Audi if the replacement part will do the same thing

 

[c2wak]

I got a custom decat and only noticed with decat. But my exhaust is the RS upgrade but it occurs even with scorpion and miltek systems as low speed.

 

[billymc92]

Here’s a few examples he is talking about. I’ve had it since February. Another boys just messaged me on Facebook today saying he has just got it after fitting same full milltek as me.

 

[c2wak]

Thats exactly the one Billy thanks for posing those.

 

[c2wak]

This lad has a Miltek Sports Cat so we know it doesnt cure it totally. This was found thanks to James from another forum so thought i would share
"I'm getting a "ticking" sound that's like an exhaust leak but after much inspection, we've chalked it up to being exhaust gas pulses that are more audible with the removal of the stock cat. You can only hear it faintly at low speed, load and rpm. Otherwise you don't notice it."

 

[billymc92]

So must be the wastegate. Could you tell me what the wastegte is and what does it do @c2wak

 

[Behind The Bins]

Here’s a few examples he is talking about. I’ve had it since February. Another boys just messaged me on Facebook today saying he has just got it after fitting same full milltek as me.

Thanks I’ll do the same as you and record

Have to say mine doesn’t appear anywhere near as bad as yours

FL standard exhaust

 

[c2wak]

You have the same tick only quieter but with a standard FL exhaust, no decat all the time. Well at lower revs more noticable?

 

[Behind The Bins]

You have the same tick only quieter but with a standard FL exhaust, no decat all the time. Well at lower revs more noticable?

Noticeable ticking noise around town

So yes lower revs

 

[JamesCrs3]

Yep, I've had a full scorpion system fitted, however opted to have the cat put back in because there is no way I can drive the car with that rattle, just sounds broken.

@billymc92 Someone correct me if I'm wrong but as I understand the wastegate helps control the boost pressure in the turbo by opening and closing in order to regulate the flow of exhaust gases through the turbine.

I'd guess that our cars have a flawed wastegate mechanism and that's why we are experiencing this dreadful sound.

This theory is backed up pretty clearly by the fact people with turbo upgrades have no such issue.

 

[billymc92]

Yep, I've had a full scorpion system fitted, however opted to have the cat put back in because there is no way I can drive the car with that rattle, just sounds broken.

@billymc92 Someone correct me if I'm wrong but as I understand the wastegate helps control the boost pressure in the turbo by opening and closing in order to regulate the flow of exhaust gases through the turbine.

I'd guess that our cars have a flawed wastegate mechanism and that's why we are experiencing this dreadful sound.

This theory is backed up pretty clearly by the fact people with turbo upgrades have no such issue.

Not a easy fix then, only cure is to get a new turbo then?

 

[JamesCrs3]

Not a easy fix then, only cure is to get a new turbo then?

Well that's the question, really we need someone who knows about this stuff to investigate and find us a solution!

 

[H4RDYRS3]

It may be possible to get an uprated actuator fitted (adjustable), then more tension/preload can be added to keep the penny flap closed until its on boost, it sounds to me like the penny flap is loose and causing the rattle off boost.

 

[H4RDYRS3]

Forge do list an actuator for the RS3 but not sure if its for the new one.

 

[JamesCrs3]

It may be possible to get an uprated actuator fitted (adjustable), then more tension/preload can be added to keep the penny flap closed until its on boost, it sounds to me like the penny flap is loose and causing the rattle off boost.

I thought an uprated actuator is only really needed when boost has been increased and thr standard spring isnt up to the job of keeping the waetegate shut?

 

[H4RDYRS3]

But with an uprated one you get adjustment on tension, tensioning up the wastegate penny flap may just cure the rattle, I'm gonna look at ordering one and get JBS to fit it and check/set up on dyno.
Will let you all know.

 

[billymc92]

But with an uprated one you get adjustment on tension, tensioning up the wastegate penny flap may just cure the rattle, I'm gonna look at ordering one and get JBS to fit it and check/set up on dyno.
Will let you all know.

I take it you have the decat rattle too?

 

[T-800]

So must be the wastegate. Could you tell me what the wastegte is and what does it do @c2wak

Billy

Waste gate on the PFL CEPA/CEPB engine

You can just see it to the right of the compressor wheel



On the FL Daza engine

But this time on the back of the new Turbo setup, you can see the actuator rod/hinge assembly.

 

[H4RDYRS3]

yes billy I have the rattle.

 

[H4RDYRS3]

T-800 is that the stock turbo on the bot pic ?, if so the std actuator looks adjustable.

 

[T-800]

T-800 is that the stock turbo on the bot pic ?, if so the std actuator looks adjustable.

Stock Turbo.

I’d be careful messing with it though as it’s preset.

Another picture (mine)

I’ve watched it on a cold start and it doesn’t move at all so no play in it.

 

[H4RDYRS3]

Do you get the tick mate ?, are you decatted ?

 

[T-800]

Do you get the tick mate ?, are you decatted ?

No Tick here.

Standard car though.

 

[Aoon_M]

The rattle comes from the wastegate, it is a vacuum actuated wastegate now instead of boost actuated. You need to understand how boost actuated wastegates work really but I will explain the best I can!

On a pre facelift RS3 8V with its boost actuated wastegate it remains shut when the duty cycle of the n75 is zero. It is fail safe this way. So on a cold start, the wastegate is shut.

On a facelift car the wastegate is reversed as it is vacuum so with n75 duty cycle zero on cold start the wastegate is wide open and it rattles.

Mappers need to set the wastegate duty cycle to 100 on cold start to stop this from happening. The reason its wide open on cold start is all to do with emissions and to get the cats up to temp as fast as possible.It is impossible to have the wastegate open on a cold start on a boost actuated wastegate


When you put a fl car into dynamic after its cold start cycle the wastegate jams shut (duty cycle 100) to aid spool! In comfort it stays open, its a very complex backwards system they have in the new engine but all for emissions purposes

 

[Behind The Bins]

So are we saying we just have to accept it

 

[Aoon_M]

Who knows. It can be fixed with mapping, I don't know if Audi will patch it with a software update as I say it is to do with emissions,

 

[billymc92]

The rattle comes from the wastegate, it is a vacuum actuated wastegate now instead of boost actuated. You need to understand how boost actuated wastegates work really but I will explain the best I can!

On a pre facelift RS3 8V with its boost actuated wastegate it remains shut when the duty cycle of the n75 is zero. It is fail safe this way. So on a cold start, the wastegate is shut.

On a facelift car the wastegate is reversed as it is vacuum so with n75 duty cycle zero on cold start the wastegate is wide open and it rattles.

Mappers need to set the wastegate duty cycle to 100 on cold start to stop this from happening. The reason its wide open on cold start is all to do with emissions and to get the cats up to temp as fast as possible.It is impossible to have the wastegate open on a cold start on a boost actuated wastegate


When you put a fl car into dynamic after its cold start cycle the wastegate jams shut (duty cycle 100) to aid spool! In comfort it stays open, its a very complex backwards system they have in the new engine but all for emissions purposes

So is there a way a mapper can stop it from the constant rattle as all us decatters have a constant rattle when under load. Not a cold start issue

 

[Behind The Bins]

So is there a way a mapper can stop it from the constant rattle as all us decatters have a constant rattle when under load. Not a cold start issue

Agreed the cold start is one thing that goes away quite quickly

It’s the constant ticking that’s annoying, but if some people don’t have it surely it’s fixable by Audi, I don’t want mine mapped

 

[Aoon_M]

Its all in the mapping, the cold start one is a simple fix but when you are in drive the wastegate being backwards I'd imagine its extremely difficult to re write the full PID tables that control the actuator.

The waste gates default position is open and the pid is all backwards so I don't know really. What would work is a boost actuated wastegate! I believe the n75 is backwards compatible with the pre facelift one. But you'd need major modifying to the turbo to change it to boost actuated.

All Iroz big turbo cars are switching to boost actuated

 

[D0C]

Great to see you on the forum again, Aoon. Always explain things well. Hope the R8 is fun!

 

[c2wak]

Be lovely to think Audi would accept this as something that needs investigating?
It's a noise that's always there, it's just only heard when the cat is removed. Surely they would have heard it while testing?!. Not sure at what stage they are tested. I have never heard of a car that cannot have it's cat removed. Maybe it was done on purpose as part of a scheme to prevent people doing it based on emissions?!.

 

[JamesCrs3]

The rattle comes from the wastegate, it is a vacuum actuated wastegate now instead of boost actuated. You need to understand how boost actuated wastegates work really but I will explain the best I can!

On a pre facelift RS3 8V with its boost actuated wastegate it remains shut when the duty cycle of the n75 is zero. It is fail safe this way. So on a cold start, the wastegate is shut.

On a facelift car the wastegate is reversed as it is vacuum so with n75 duty cycle zero on cold start the wastegate is wide open and it rattles.

Mappers need to set the wastegate duty cycle to 100 on cold start to stop this from happening. The reason its wide open on cold start is all to do with emissions and to get the cats up to temp as fast as possible.It is impossible to have the wastegate open on a cold start on a boost actuated wastegate


When you put a fl car into dynamic after its cold start cycle the wastegate jams shut (duty cycle 100) to aid spool! In comfort it stays open, its a very complex backwards system they have in the new engine but all for emissions purposes

Good info, however doesn't really explain why it is rattling? Surely every car with a vacuum wastegate doesn't make this sound?

 

[T-800]

Here's a clip of the DAZA engine at cold start cycle.......



Another when warmed up