MK5 Golf GTI

All Things Mk5 => Mk5 General Area => Topic started by: Ashley g on May 12, 2012, 11:31:32 am

Title: Fluttering noise on boost
Post by: Ashley g on May 12, 2012, 11:31:32 am
Morning all. My car seems to be making a fluttering sound on boost. It's really noticeable when accelerating in 6th gear at around 3500rpm, sometimes in 5th gear too. I've just fitted a revision G diverter valve as the old one had a split diaphragm. It transformed the performance of the car but now notice the fluttering noise. Has anyone got any ideas? My mods are in my sig below.
Thanks in advance, Ash
Title: Re: Fluttering noise on boost
Post by: GrayMK5GTI on May 12, 2012, 12:03:48 pm
Does it feel like the car is misfiring?
Title: Re: Fluttering noise on boost
Post by: Ashley g on May 12, 2012, 12:06:58 pm
Doesn't feel like a misfire, had new coilpacks fitted at VW this morning and checked the plugs which are only 1500 miles old
Title: Re: Fluttering noise on boost
Post by: GrayMK5GTI on May 12, 2012, 12:11:35 pm
Mine was fluttering and sort of hesitating (even after new plugs) at low revs under hard boost, so I reduced the gap on the spark plugs down to 0.67mm and it's spot on  :happy2:

Apparently high boost sort of blows the spark off the plug or something.
Title: Re: Fluttering noise on boost
Post by: Lee M on May 12, 2012, 09:24:12 pm
Hi mate,

Fluttering noise is normal. My Cupra does the same thing. It's controlling the boost level and is a normal occurrence.  If its not effecting the drive then don't worry about it.

Cheers lee
Title: Re: Fluttering noise on boost
Post by: PDT on May 12, 2012, 09:28:40 pm
Hi mate,

Fluttering noise is normal. My Cupra does the same thing. It's controlling the boost level and is a normal occurrence.  If its not effecting the drive then don't worry about it.

Cheers lee


Flutter noise is usually caused by boost control, totally normal.
Title: Re: Fluttering noise on boost
Post by: Ashley g on May 13, 2012, 10:04:19 am
Ah so it's normal then? Where dies the fluttering noise come from? It's running the standard ngk plugs, what should these be gapped to?
Cheers for the help so far!
Title: Re: Fluttering noise on boost
Post by: E30Dom on May 13, 2012, 10:39:05 am
It's the pcv/diverter valves controlling the amount of boost...
Title: Re: Fluttering noise on boost
Post by: Lee M on May 14, 2012, 09:28:39 pm
Ah so it's normal then? Where dies the fluttering noise come from? It's running the standard ngk plugs, what should these be gapped to?
Cheers for the help so far!

Hi mate. Yes normal function. I'm pretty sure plug gap is 0.8mm
Title: Re: Fluttering noise on boost
Post by: Lee M on May 14, 2012, 09:30:46 pm
Ah so it's normal then? Where dies the fluttering noise come from? It's running the standard ngk plugs, what should these be gapped to?
Cheers for the help so far!

Hi mate. Yes normal function. I'm pretty sure plug gap is 0.8mm

Saying that I'm basing that info. on my Cupra engine, so yours might not be the same
Title: Re: Fluttering noise on boost
Post by: alackofspeed on May 14, 2012, 11:14:38 pm
It's the pcv/diverter valves controlling the amount of boost...

PCV - I hope not!

The PWM control of the n75 on a friend's 1.8t running a MBE had a very distinctive flutter from the exhaust. Relatively low frequency square waves it seemed, so it made distinctive pfft, pffft, pfft as it went down the road at full boost.
Title: Re: Fluttering noise on boost
Post by: E30Dom on May 15, 2012, 02:05:10 pm
sorry meant the n75 valve thingy... :innocent:
Title: Re: Fluttering noise on boost
Post by: Ashley g on May 16, 2012, 11:28:23 am
So it's totally normal for the N75 to make this fluttering sound then? Only I've never heard one make a noise before!
Title: Re: Fluttering noise on boost
Post by: john87 on May 16, 2012, 12:24:06 pm
My gti does this under full boost, can sometimes hear the occasional flutter through the TWINtake  :happy2: no effect on performance!
Title: Re: Fluttering noise on boost
Post by: rich83 on November 12, 2012, 10:20:00 am
FECK.... mine flutters like buggery with my intake on  :scared:
Title: Re: Fluttering noise on boost
Post by: monte on November 12, 2012, 10:33:20 am
FECK.... mine flutters like buggery with my intake on  :scared:

Mine too.
Title: Re: Fluttering noise on boost
Post by: Shorty on November 12, 2012, 10:37:24 am
Yeah it's totally normal, mine used to do it until I tuned up the boost..
Title: Re: Fluttering noise on boost
Post by: fab5freddy on November 12, 2012, 11:35:34 am
Mine go's mental when pushing on  :rolleye:
Title: Re: Fluttering noise on boost
Post by: keano on November 12, 2012, 12:02:03 pm
I got 6 billion times more flutter after my stage 2 map.

As mentioned before, totally normal.  :evilgrin:
Title: Re: Fluttering noise on boost
Post by: rich83 on November 12, 2012, 12:04:20 pm
I got 6 billion times more flutter after my stage 2 map.

As mentioned before, totally normal.  :evilgrin:

 :happy2:

Ive read that its the N75 valve regulating boost pressure... not sure if thats true.