Turbo Flutter :(

[FandangoDanby]

Hi guys,

After some know how, here's the story, 3 weeks ago I did a lot of work on my car, 2 of the bits I changed which could have caused this are the DV (Forge 008p yellow spring) and a Forge TIP, now it doesn't matter if it's been programmed with stage 1 or original (I have the box to change it whenever I like) but in the last week, whenever I have turbo boost (all gears) and I let my foot off the accelerator I get a light fluttering/chattering for about a second from the airbox area of the car. Now bearing in mind it was fine for 2 weeks not a peep as well I'm a bit baffled.

The turbo is a KO4 on a BAM engine.

I have taken the DV apart, checked it, everything is fine. I was under the impression a stage 1 using a yellow spring was a good idea but I could switch to green if people think it would be better, maybe put all 3 shims in as well?

I haven't run an n249 bypass as yet, considering it due to this though if people think it might help? The only other thing I could think of is it's the waste gate but I haven't got a friend with me to check it as I'm away on business.

How long realistically could I drive with it like this before risking serious damage to the turbo? If it would damage it at all?

Thanks lads/ladys.

 

[ibizacupra]

too stiff a spring or sticking dv or leak so dv does'nt see the vacuum it needs to open.

 

[FandangoDanby]

I've ordered a green spring, and some new mobil lithium grease to use in the DV, if that doesn't work I guess it's going to be a leak somewhere! Thanks Badger as always very helpful.

 

[FandangoDanby]

Right, if anybody can help out now I'd appreciate it, I've serviced the DV, replaced the spring with a green, checked it holds vacuum (finger over nipple push piston up etc) and it's fine, I've also removed the vacuum pipes and checked those and they are also fine, all the way to the inlet manifold. I am still getting flutter, what's everyone's thoughts?

I should point out i've run an n249 bypass as well so none of the other pipes are a concern around that area.

 

[ibizacupra]

if you have vacuum direct from inlet manifold to DV in suitably bore pipe, and you can see you have vacuum at the DV by checking its sucking it should work.
possibly your n249 bypass is'nt correct otherwise

 

[FandangoDanby]

Badge, the bypass was simply a hose connector between the inlet to n249 pipe and the dv to n249 pipe, I've taken the apparatus off still connected to the DV and checked the hoses retain vacuum and they do... I am officially stumped!

 

[ibizacupra]

got the original one still? refit it

 

[FandangoDanby]

That was next on my list of things to do. I was reading somewhere that I may be mistaking flutter for the operation of the DV? Is it possible that the noise I'm hearing is just the piston performing it's job rapidly? I must admit it's lacking the metallic sound people report with chatter, just seems to be air out of the airbox area of the car. The DV dumps air back into the intake pipe which would kind of make sense here because the turbo is spooling down it isn't sucking in air so that diverted air has to go somewhere... Feel free to correct me if I'm extremely wrong here! lol

 

[ibizacupra]

flutter is a "flutter" noise... DV venting is a Woosh noise
https://youtu.be/AQbgEJs2owk

^^^ flutter ^^^

 

[dubslife]

I had the exact same problem 2 weeks ago 2005 bam but with n249 fully fitted and it was the vacuum line to the top of the dv was kinked when I changed the plugs I didn't route the vacuum lines properly but I since done the n249 bypass and the flutter went away.for what it's worth I was running the yellow Spring on a 008 with stock 225 lump and didn't have any problems holding boost or it fluttering at all.my advice would be put the standard dv back on and take it for a spin see if it still does it and make sure the dv pipe to the mani isn't bent at all restricting flow

 

[FandangoDanby]

I'll give it a double check Dubs thank you, what a pain.

I have got new red vacuum piping and clips coming so I'll try installing that and see if that makes a difference too, 4mm internal bore all the way through, no stupid connector!

this is exactly what I'm getting https://www.youtube.com/watch?v=Ua6MPrxHn8g

 

[dubslife]

I'm using red ram air 4mm vacume and a brass 5mm joiner again just stating my set up for comparison I was going to run the 4mm straight from mani to dv rather than using a joiner but haven't got around to doing so yet but using the original black vac line as joining it to a new 4mm line still shouldn't cause issue.do you run an engine cover? Make sure that isn't pushing down against the top of the dv to much.and actually make sure the dv isn't fitted upside down? Sounds stupid but people do fit them wrong ?

 

[FandangoDanby]

I do run an engine cover, I didn't think to check if it was pressing purely because the right side clip (as you look at it) at the back is snapped so it shouldn't be applying pressure to that area, but I'll have a look.

The DV is installed in the same orientation as the stock was, with vacuum nipple facing up towards the bonnet. I was tempted to swap it around to see if it was a cure...

 

[FandangoDanby]

Right so update, my new silicone vac pipe came today, so I replaced that, used 6-12mm hose clamps to seal at both ends (outer diameter of pipe is 8mm), and I still have the flutter. It's driving me up the wall now I have no idea what else it could be..

And there are no kinks/obstructions on the vac pipe either. I know the DV works, I know the pipe must be fine, what else is there?

 

[FandangoDanby]

I'm pleased (and somewhat mortified) to report that the problem is 98% cured, the rubber pipe from the alloy boost pipe to the DV was pinched behind the vacuum housing above the n249... How embarrassing, but in my defence it was hidden behind that flap of heat shielding, still getting a tiny amount on throttle off but I've got a 100 mile drive tomorrow so I'll report back afterwards! Might even be the yellow spring is needed again lol.