jcain

Just curious, driving against a wall the other day with the window down, the first heavy spool up after cranking the truck (2nd gear) I heard a fluttering sound from the passenger side. Let off and tried to recreate, but nothing. Now, everytime I spool the turbos the first time of the drive cycle the same fluttering/chirping occurs, then never happens again. doesn't matter if you let the truck sit all night, or 30mins, the first hardy spool of that drive cycle makes the noise then never again.

Anyone else? Seems like a sticky bypass valve or a lazy bearing.

MadocHandyman

I've never noticed.
Maybe it's calibrating something each cycle??

ninjatalon

iTrader: (1)

What do u mean lazy bearing? also im pretty sure its not the bov. It wont cause turbo surge during start up or idle

jcain

its not surging. its chirping almost. i'll have to get a video out it.

ninjatalon

iTrader: (1)

yea i was gonna ask for a video so we can all hear it. When you said fluttering that why i automatically thought of surging.

jcain

best video i could muster. the sound doesn't really get picked up by the camera. if you crank up the sound though you can surely here it

http://youtu.be/39FP6aTU3Wc

Kenneth Forbus

Everything sounded good to me. Turbos spooling echoing off that wall and the internal blow off dumping all the boost that got built up once you let off the gas pedal.

jcain

There is a high pitch screeching there. This is my 4th turbo vehicle. Something is off, it'll do it now in park with a rev during first start. I'm wondering if its one of those twirly bobs in the intake tract.

klumb15

Is it happening right when you let off the throttle? It's hard to hear in your video but it sounds like compressor surge to me. Maybe the bypass valve is out to lunch.

geno51

Yes I hear the screech and that does not sound like the Norma blow off something is not right take it in!!