Noise when letting of throttle, aka Let's Play Guess That Noise!

Ok, I took some videos last night of the car. Apologies for poor volume... this is a crappy cell phone, but it's much better than nothing.

Please pay attention to the noise I get after shifting.

It does it in all gears, no matter the rpm. It's a lot more audible at higher RPM so that's where I shifted (4k). But it's there even at 2500 rpm shifting from 1st to 2nd.

EDIT FOR MORE INFO: It happens anytime I let off the accelerator... so even coasting in gear it makes that drone noise. I should have taken a video of that, sorry. But it's the same sound.

EDIT FOR MORE INFO: I compared the injector tick with the ol' screwdriver to the ear method... injector 1 is noticeably louder than the others, and the Injector balance (group 13) shows that one in the positive, while the others are in the negative range. I'll see if I can get exact values.


ALH, 245k, stock except for some cheapo .205's (from original owner).
I do have a weeping EGR (recently started to weep). Cam and lifters were replaced 2k miles ago, but this noise has been there long before. Intake and EGR were cleaned 15k miles ago. Compression is 415/440/440/420 on a warm engine.


Idle, Engine Bay Shot.


Driving, 4k shift in 1st and 2nd, 3k into 3rd. Listen for that drone noise.


Driving, 4k shift in 1st, lower in 2nd. Listen for that drone noise.


Reving in Neutral



Note: The white wire you see is my VAG-COM cable plugged in and draped across and out of the way.

My guess...

The fact that you have the noise in gear only (not in neutral) suggests that the torque of the engine (and how it moves the engine) is the factor that causes the noise. I would look at the exhaust piping or other piping that could be rubbing when the torque of the engine changes.

My .02, jfw

I hear a couple of things. In the first video, it sounds like you have a pulley that is squeaking.

In the second video (free-revving), it sounds like you have a boost leak.

In the other videos, I have no idea what that sound is as the RPMs are dropping while you shift.

Important piece I did not mention...

The noise is also there when I coast in gear. So it's anytime I let off the accelerator pedal.

I will look into a possible boost leak - I will try to log boost tonight and post results. The MAF is good.


((I edited my first post for new readers.))

It would seem from the videos that the noise seems to change as engine speed decreases. Is this accurate, or does the noise change with vehicle speed?

VeeDubTDI said:

It would seem from the videos that the noise seems to change as engine speed decreases. Is this accurate, or does the noise change with vehicle speed?

Click to expand...

Tough call...

I think the noise is the same regardless of engine speed and vehicle speed.

I could be going 2000 rpm in 2nd, and coast or shift, and it drones the same. It is just a lot more pronounced at higher RPMs since everything is louder.

Maybe the pitch changes, but I consider it the same effect.

Letting off the accelerator, whether it's to coast or to shift, results in the noise.


If I understand you correctly, we're figuring out if it's chassis dependent (axles, CV, trans) or engine dependent (drivetrain).

Is the noise same with the car in gear and the clutch out (ie, coasting in gear, perhaps down a hill)?

Ok I did a lot more listening today...

the tone of the engine changes at 2200 on its way up. you can make out the drone on its way up, if that makes any sense. when i let off the throttle at 3000 or more, you get that drone. since the rpm's drop faster on the way down, the noise may just be more pronounced and noticeable at this point.

if you listen to the driving videos, above 2200 there is a change in engine sound. this is where the car really builds boost, which i don't know is a coincidence or the cause.

my above post says 2000, but the more closely i listen, it's really above 2200 to 2400 where it begins. shifting above that creates the noise on lifting off the throttle.

there are zero hills here, so no chance to coast down the hill. but letting it coast from speed makes no noise. it drives very well and makes good power, especially in 3rd and 4th around town, in the 2000-3000 rpm range.

the noise is much more noticeable in 1st and 2nd, so increasing load in the higher gears may not create it as much, or maybe the other road noise is masking it.

jfwdc said:

The fact that you have the noise in gear only (not in neutral) suggests that the torque of the engine (and how it moves the engine) is the factor that causes the noise. I would look at the exhaust piping or other piping that could be rubbing when the torque of the engine changes.

My .02, jfw

Click to expand...

I recently had the downpipe off and back on. The noise has been there before and after. The downpipe and catback are all installed like they're supposed to be, and there is no rubbing or interference anywhere.

VeeDubTDI said:

I hear a couple of things. In the first video, it sounds like you have a pulley that is squeaking.

In the second video (free-revving), it sounds like you have a boost leak.

In the other videos, I have no idea what that sound is as the RPMs are dropping while you shift.

Click to expand...

1. i hear that too now, thanks for pointing it out.

2. it does sound "wooshy" in the video but in person it sounds purely mechanical. i free rev'd it today to make sure, and it doesn't have the wooshy sound in person. the car builds good boost and drives really well, aside from the noise!



thanks for your input everyone.

Well, keep on trucking and see if the noise gets worse.

The noise has been there since I bought this car 20k miles ago.
It has not gotten worse, but I'm more in tune to the noise now that I've gotten the car running much better than it was when I bought it.


Does the EGR make noise? It recently started leaking and has been getting worse, little by little. Is there anything there that would cause a noise?

I have no slow down shudder issues and IQ is set at 5.0

This is getting buried quickly! Any other opinions on the off-throttle noise?

I believe the same noise that starts above 2200 rpm while reving up, and it's much more noticeable on the way down as the RPMs drop faster.


Does a leaking EGR make any noise? Could an ASV issue be causing this?


I will be going through the turbo piping connections and intercooler connection this week, and will be replacing all vacuum lines this week and see if that improves things. But there are no noticeable driveability issues, just the 'groaning' or 'straining' noise.

Sorry to bump, but I'm hoping more people see this thread and have some comments.



(I'm trying to get the car to a guru, but he is 2 1/2 hours away and it's been hard to schedule anything.)

this got buried again! did anyone have any luck with this?
my mk5 with BKC engine is making the exact same noise...

free bump for ya..

apples12: can you get a high quality video of the noise? The OPs videos are tough to figure out what's going on.

Hi
i'm gna try to embed...lol. ignore the dirty engine bay and the upside down oil cap...
<iframe width="560" height="315" src="http://www.youtube.com/embed/9f9VgnhhUjM" frameborder="0" allowfullscreen></iframe>

http://www.youtube.com/watch?v=9f9VgnhhUjM

Up...

Sounds like a boost leak somewhere.