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Discussion Starter #1
My beautiful new 4mo, 5-speed 1.8t passat wagon now has 1,400 miles on it and I have just begun to drive it with a bit more spirit. Yesterday I noticed, in the midst of Manhattan evasive maneuvers, a strange sound following brief bursts of full throttle at about 2000-3000 rpm. After a quick release of the accelerator from the full throttle position at the above rpm range, there is a "trailing off" noise sounding something like a scraping metalic rasping exhallation; almost like a metalic wheeze. It lasts scarcly 1-2 seconds. I've never owned a turbo equipped vehicle and, I wonder if the sound is simply the turbo spinning down after the full throttle burst. I don't notice the sound from 1000-2000 rpm when perhaps the turbo hasn't kicked in. And, I don't hear it after 3000 rpm, --perhaps becuase the engine noise drowns it out? Is this type of sound normal for the 1.8t engine? Might I have a problem? Please help shed light on this if possible. I'm worried about my new baby! Thank you so much.
 

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well it does not sound familiar to me, but i think at this stage, its new bring it to the dealer :wink: :poke:
 

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I have the same sound as you describe. I hear it under the same driving conditions. My 04 is an automatic. I posted a question about a month ago. Can't remember whether it was on this forum or VW Vortex. The replies seemed to indicate the sound was a normal function of the turbo.

When my 04 was in for another issue I asked about it and they said the same thing.

I never heard that sound on my 98 or 01.5 Passats.
 

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Discussion Starter #4
I took it to the dealer yesterday and, they said it was normal and related to the turbo. I'll get more details when I pick it up...
 

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Maybe it's the sound of the air whipping through the diverter valve. It's opening isn't quite as wide as the standard pipe from turbo to intercooler and it cuts a 90 degree angle.

Just my guess since, at WOT, the turbine is going to be spinning pretty fast and pushing quite a lot of air.
 

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Sounds to me like a bad description of what turbo whine sounds like. It's the best part about owning a 1.8T. I hope you like that sound because I almost find it exciting. :D
 

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znalg said:
My beautiful new 4mo, 5-speed 1.8t passat wagon now has 1,400 miles on it and I have just begun to drive it with a bit more spirit. Yesterday I noticed, in the midst of Manhattan evasive maneuvers, a strange sound following brief bursts of full throttle at about 2000-3000 rpm. After a quick release of the accelerator from the full throttle position at the above rpm range, there is a "trailing off" noise sounding something like a scraping metalic rasping exhallation; almost like a metalic wheeze. It lasts scarcly 1-2 seconds. I've never owned a turbo equipped vehicle and, I wonder if the sound is simply the turbo spinning down after the full throttle burst. I don't notice the sound from 1000-2000 rpm when perhaps the turbo hasn't kicked in. And, I don't hear it after 3000 rpm, --perhaps becuase the engine noise drowns it out? Is this type of sound normal for the 1.8t engine? Might I have a problem? Please help shed light on this if possible. I'm worried about my new baby! Thank you so much.

Definitely just sounds like the Diverter Valve functioning normally. It probably isn't a very loud noise, but it's always present after you let off the gas after tromping hard on it. All that's happening is the Diverter Valve is opening, allowing the pressurized air downstream of the turbocharger to be released back into the intake stream before the turbocharger. It's basically designed to keep the excess pressure from open-then-closed throttle situations from damaging the turbocharger, and is completely normal.
Now, if you were to get a Blow-Off Valve, the noise would be noticeably louder. Instead of the air being redirected back into the intake tract, it's vented to the atmosphere for all to hear. Granted, the newer 1.8Ts don't like it as much as the older ones, but that's a whole other topic that I don't really feel like bringing up right now. :lol:

Enjoy your 1.8T 4Motion. I know I would. 8)
 

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I remember hearing this when mine was new (I've got an 03 1.8t tip). Either I don't notice it anymore or it's gone, but no ill effects. Probably the DV.
 

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The reason you don't hear it after backing off from 1-2k RPM is as you suspected... the turbo hasn't kicked in yet. It spins up at around 2300 RPM, as only then is there enough exhaust volume to have the turbo spinning fast enough to be worthwhile.

SirWired
 

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Discussion Starter #12
You guys are good. I picked up the car from VW service and, they basically confirmed your suspicions: the car was terrified in Manhattan... Poor baby...
Now the other thing they mentioned was,

" the Diverter Valve is opening, allowing the pressurized air downstream of the turbocharger to be released back into the intake stream before the turbocharger. It's basically designed to keep the excess pressure from open-then-closed throttle situations from damaging the turbocharger, and is completely normal."

Thanks much. Now that I know it's normal, I don't mind it at all!
 
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