Whistle when you let off gas

[Taylor3180]

Just installed a 1g bov with a Dejon UICP. The whistle happens when I am on the gas and let off without even boosting. But when I am on the gas and boosting there is no whistle. Just at certain times when I just tap the gas and let off when it's idling. It's very high pitched. I don't know how else to explain it.

 

[DirtyBirdRacing]

Hi,

Did you do a boost leak test after you installed the BOV and UICP? It sounds like you might have a vacuum leak.

Bill

 

[Taylor3180]

That's what I thought but I figured I would also hear the whistle while on the gas not just letting off. And I did do a test and couldn't find one anywhere.

 

[JusMX141]

My 1G FWD does it, and my buddy's 2G TSi AWD does it as well....we both have very different setups.

One thing is common between both cars....hack 2G Mass Airflow Sensors. I always thought it was just a whistle through the intake from the hacked MAS and ignored it.

 

[absolute_DSM]

I would thoroughly check for a vacuum leak doing a boost leak test. That most likely is your problem. Also make sure your bypass valve is operating correctly. It may just be your valve releasing.

 

[Taylor3180]

It happens at real low RPM's to. I guess I'll just have to get used to it.

 

[DirtyBirdRacing]

That's what I thought but I figured I would also hear the whistle while on the gas not just letting off.

It might still be there, but you just cant hear it due to loud exhaust and the engine reving out while you are flooring it.

Bill

 

[kmoore]

I had the same issue when my greddy type RS crapped out on me. Turned out that the metal diaphram was stuck open. If I were you I would pull off that BOV and make sure the diaphram is sealed against the base of the BOV.

 

[Taylor3180]

Thanks for all the help so far. I will be checking everything out in the morning. Though I did have the hood popped and a body right next to the car as I would hit the gas you wouldn't hear the whistle at all. And it's just a small chirp it's not like a full out whistle. Just a small high pitched chirp just as you let off the gas pedal. Like I said I am not even building boost when I notice it. And I don't have a loud exhaust check the Profile it's all stock exhaust yet.

 

[JusMX141]

For me, it happens while driving at very low RPM with little engine load (say, in 5th at 45-50mph) and while moving it around my driveway.

I know it's not a leaky BOV- my buddy's 2G that also makes the sound was running 22psi last summer.

 

[turboglenn]

My crushed 1G BOV did that same thing, what it turned out to be was that the turbo was still spinning enough to push air, but there was vacuum in the manifold keeping the BOV open. Since it was crushed it wasn't opening very far it was whistling from the air coming out of the tiny passage, and i guess the shape of the opening promotes a bit of a whistle too.

I could rev it from the TB housing and feel the air coming out as the motor delcerated and the BOV whistled using my other hand.

While you are on the gas enough to have 0 vacuum or boost the pressure and spring will be holding the BOV shut, so it's not really leaking, it just the way it's opening under moderate vacuum and the air coming out.

 

[FonZ454]

It's just your 1g bov. Basically all of them do it. More so with hard piping/ venting.

 

[DSMunknown]

^ I would agree. I know I don't have any boost leaks, and I always get a high pitched ring right at 18in.Hg. No more, no less. It's normal with the 1G BOV, unless you have boost leaks.