On the way home I noticed I suddenly have some flutter when coming off the throttle. I changed the DV to the newest OEM one recently to try and remove the classic over revving issue between gears and also did the n249 delete. (It didn't solve it BTW) This was about 6 weeks ago and about 2 weeks ago I fitted a Badger TIP and Jetex filter. From looking at it in the dark tonight I can see that everything is attached to the DV as it should be and nothing appears to be cracked or loose. I am still running standard rubber hosing but the car is new to me as of 3 months ago so I'm not sure if they have been changed in its 13 years of life. Is it likely the DV has killed itself already? I still have the older one from when I replaced it which I will try on tomorrow but I'm hoping it's nothing more serious. If that doesn't work what is the next step? Since changing to the Jetex the off the throttle noise has gradually become more of a pssssshhhhh instead of a pshhtt come to think of it but I could be wrong.. Here's hoping my turbo is ok..
Turbo Flutter?
- Thread starter DarkSideOfTheMoon
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ceS3r
Registered User
Don't worry, your turbo is okay.
You're getting the flutter (like a Supra) because your car is not generating enough vacuum to lift the rubber diaphragm (assuming you have the OEM 710N Diverter) and not letting the air escape. This means that the air after you lift throttle goes back to the still spinning turbo blades hitting with them and creating that flutter noise. Please note that this is increases wear on your turbo bearings.
If you suspect your dv is ******, you can switch with your old one and see. If not, check the hoses leading from the top of the dv to the bottom of the manifold. n249 delete is pretty easy, just remove everything from the system and run a single line from the top of the dv to one of the nipples on the bottom of the intake manifold.
You're getting the flutter (like a Supra) because your car is not generating enough vacuum to lift the rubber diaphragm (assuming you have the OEM 710N Diverter) and not letting the air escape. This means that the air after you lift throttle goes back to the still spinning turbo blades hitting with them and creating that flutter noise. Please note that this is increases wear on your turbo bearings.
If you suspect your dv is ******, you can switch with your old one and see. If not, check the hoses leading from the top of the dv to the bottom of the manifold. n249 delete is pretty easy, just remove everything from the system and run a single line from the top of the dv to one of the nipples on the bottom of the intake manifold.
ceS3r
Registered User
I wouldn't know really. I've read somewhere that it "reduces" turbo lag but I did the delete to my car and didn't notice any change at all.
Some guy from GT-Innovation (a custom remap company) told me that with the n249 properly working he could make the turbo spin a little bit faster, but I really don't know.
Benefits are cleaner engine bay and reduce the risk of having leaks.
Your over revving issue between changing gear could be your clutch pedal switch as I had that problem a few years ago, changed the switch and the revving went.
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Turns out it was the new DV that had killed itself. It was actually the newest 710P and I have now put the old N one back in and no more flutter (who knows how old that one is!)
ceS3r
Registered User
I believe the 710N one is the newer one. I have a friend who has a 300+hp vw golf gti mk4, with a garret gt28, and he's running it with the 710N with no problems whatsoever!
Glad you found out the issue.
According to where I bought it the 710P is the newest and "includes an improved design with internal guides that now hold the sealing lip in alignment with the seat." It clearly didn't work in this case!
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I changed my clutch switch too - it is often down as a cruise control switch if look on ebay, make sure you get the right one though. it is possible to replace it without any trim removed but you really need someone to shine a torch down the shelf and to fit the new one is easier if someone presses the clutch down somehow maybe with a stick or their right leg sitting in the passenger seat.
When looking at the N249 delete after doing mine if extra box actually holds the turbo on boost between gears one and two for smoother acceleration, is the 710P broken or was the fitment leaking?
When looking at the N249 delete after doing mine if extra box actually holds the turbo on boost between gears one and two for smoother acceleration, is the 710P broken or was the fitment leaking?
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Just to clear up what the N249 is/does. It allows the ESP system to interfere with the boost and dump it when it cuts in. The black box stores a vacuum for when its needed
Also, 'turbo flutter' = technical term: compressor stall
Also, 'turbo flutter' = technical term: compressor stall
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ESP works by controlling load (throttle plate and boost through N75)... N249 is an all or nothing solution so not precise enough for ESP...
ESP info can be found in this self study PDF..
http://www.volkspage.net/technik/ssp/ssp/SSP_204.pdf
N249 is mainly a protection system to allow the ECU to dump boost in case of an over boost situation..
It also serves a purpose or part throttle to allow air to be drawn in directly to the charge system bypassing the turbo compressor which I believe improves throttle response in some instances... can't say I have tried it myself though
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