Strange knock on lift-off since Evoms fitted (video)

[ADi Nuff Valves]

As per the title, i've just fitted an Evoms v-flow to my S3 today and now i'm noticing a single knock noise when I lift off the throttle and the revs drop. It seems to occur roughly as the revs drop below 1000 rpm. You should be able to hear it in this video:

Audi S3 8P lift-off knock - YouTube

Anybody got a clue as to what might be causing that?

 

[MartayMcFly]

Hmm... not a clue really. Sounds like something closing as the revs drop, maybe cam related? Afraid you'll need someone more mechanical to get their head under bonnet, unless it's something common and someone else already knows what it is.

 

[ADi Nuff Valves]

Thanks. Yeah I really can't put my finger on it. Wonder if it's always been there and the new intake has just highlighted it.

 

[MartayMcFly]

Might just be something you'd only notice with the bonnet open so, like you say, you just hadn't heard it before.

 

[DeckedS3]

Did you install the heat sheild?
If so, that may be hitting the back of the engine bay.... Cant watch the vid as i'm at work.

 

[ADi Nuff Valves]

No I don't have the heat shield.

 

[DeckedS3]

Just has a listen and it doesn't sound like anything mine does..... Weird!

 

[ADi Nuff Valves]

Hmmm, this has got me quite worried. Tempted to take the Evoms off and put the stock filter back on to see if I can still hear it. I just can't see why the Evoms would cause anything like that unless it was physically knocking against something. I can't see it moving much but it's difficult to have much of a look under the bonnet when you need to blip the throttle as well.

 

[Denty]

Hmmm, this has got me quite worried. Tempted to take the Evoms off and put the stock filter back on to see if I can still hear it. I just can't see why the Evoms would cause anything like that unless it was physically knocking against something. I can't see it moving much but it's difficult to have much of a look under the bonnet when you need to blip the throttle as well.

ive got this on my s3 and it had me a bit worried untill i figured it out.... try pinching the [h=1]Diverter Valve to Intake Return Hose[/h] with some mole grips or the like and then blip ur engine.... i bet the knocking sound wont be there anymore... solution - fit an forge uprated silicon pipe to prevent deformation caused by the extra airflow that ur new intake causes......



i thank ya

 

[ADi Nuff Valves]

ive got this on my s3 and it had me a bit worried untill i figured it out.... try pinching the Diverter Valve to Intake Return Hose

with some mole grips or the like and then blip ur engine.... i bet the knocking sound wont be there anymore... solution - fit an forge uprated silicon pipe to prevent deformation caused by the extra airflow that ur new intake causes......



i thank ya

Really? Wouldn't you see the pipe deforming if it was? Is this the correct pipe i've highlighted below?



The noise seemed to be coming from around the cone filter, maybe below it. Anyway, i've put the stock filter back on for now to check the noise isn't still there and it didn't appear to be.

Didn't realise Forge did a replacement pipe. Might be worth a try i guess. Got any links?

 

[Denty]

thats the one mate...you cant see it by eye deforming..... try fitting the new version diverter valve from audi at the same time as fitting the pipe - the noise should go


Forge Motorsport FMRLH Diverter Valve to Intake Return Hose S3 8P / S3 8P Sportback 2.0T FSi Quattro 11/06> - £49.10 : The premier online mail order VAG suspension and performance specialists. We offer a wide range of all the best branded suspension

 

[Acheron]

Mine makes the EXACT same sound and I've not noticed any issues relating to it.

 

[ADi Nuff Valves]

I've got the new rev D diverter. Thanks for the link. £50 for some pipe seems a tad steep!

Cheers Acheron. I've taken the kit off for the time being but I might have to put it back on if I know it won't cause any issues.