Rev Hang / Sticky Revs + squeal coming off boost

[muff1991]

Hi All, apologies for the essay... please hand over any advice before i waste money lol
Virtually standard 2006 Manual GTI with only a Ram Air induction kit and back box delete.
i have read a lot online and searched on here but i cant find nothing that points me in the right direction.
so when I'm sat in traffic and move forward... obvs throttle on clutch up and then stop - off throttle clutch down... the revs stick and hover for a second or so and most of the time the revs drop real slow! my last GTI never did this so i cant except that "Rev hang" is normal like ive read online :( do you guys and girls get this on yours?
sometimes its worse than others, and happens normal driving too! i even sat there once and just reved without touching clutch pedal and it sticks there too! as i read it could be clutch switch.

along with this issue, i also get a horrible noise when changing gear.. and I really don't want to settle for CAI harmonics as my mates GTI doesn't do this with same set up. only difference is he does have the DV+ and a PCV delete. I have the Rev G and i did read this could be the problem, but other people have tried the DV+ and its not cured the problem. do any of you get this? its exactly what this guy in the video suffers with... listen when he changes gear and comes off throttle.

i have a feeling these issues could be linked you know... almost like maybe the throttle body doesn't close properly straight away and not shutting the DV off instantly.

any ideas? any help or advice will be greatly appreciated. i know its a lot but if you need more in depth info as i know i wouldn't have explained this that well please let me know.
thanks :)

[Chesto18]

No help at all I’m sure, but whenever the Mk2 GTi’s used to have ‘idle hang’ as you described it it was the ISV (idle stabilisation valve) playing up. That, or the idle hadn’t been set properly and thus the ISV was working too hard to bring it back down.

Literally no idea if the Mk5 has similar components/issues here,

The noise does sound like a bit of an air leak. Especially as it’s happening between gears when your DV should be letting off pressure. Have you checked the DV?

[muff1991]

Hi Cheeto, yeah I’ve checked my Dv, took it all apart to check the diaphragm properly for any splits. I read something on a site from 6 years ago today and this guy said it was the Dv relocation bit on the intake pipe which is currently bunged off. He said he had a nylon sleeve made to block it off as he reckons the gap in there was causing an air trap and causing the resonance. So I might give that a go but still hard to believe when my mates doesn’t do it.

Thanks for the info about ISV i am going to get a throttle body alignment done and clean it before I do to see if it helps. Other than that and without replacing things I’m not sure where to look tbh.
Also read about a pipe from the vacuum pump being split so need to check that too. And noticed I only have 3 bolts holding PCV housing on. So need to get a new one of those.
Finally, I read about a pipe coming from the n75 near turbo can get clogged with crud and oil etc so might take all those pipes off and clean them if they’re easy enough to reach.  Thanks again Cheeto.

[muff1991]

i was reading online about the RAM AIR inductions kits and come across a guy saying he had the squeal issue... and fixed it!!
He was saying about the nipple bit on the curve of the intake just before the turbo inlet (for the DV relocation pipe), it has a little bung over the top if you have the standard DV to obviously blank it off. He said he fixed it by having a nylon bung made (with a t-piece on so it wouldn't fall through) to insert into the hole and close/eliminate the hole completely.
he reckons the nipple/hole/tube bit must of been causing a resonance as it would of trapped air inside.
worth a go i reckon, i just thought I'd share this.