Funny Noise When Releasing Throttle

[CowPimp]

My car is a 96 TSi AWD. My performance mods consist of:
FP Big28
3000GT Fuel Pump
EVO Ported Exhaust Manifold
Custom 2.5" Turboback 02 eliminator
Dejon Tool Intake & KN Filter
Dejon Tool U/L IC Piping & Throttle Body Elbow
Hallmon MBC
Boost & A/F Gauges
Short Shifter
ACT2100

Sometimes when I release my throttle from being held down about 30% or more I hear a squeak noise. It sounds like a light metal brushing against metal sound. The length of the noise is approximately that of a tire chirp (Fraction of a second). I can only hear it with the windows down and the music volume low. I can't seem to remember when the noise began. I have done a lot of mods in a short period of time, so trying to determine which mod this could be related to (If any) is pretty hard. Also, if I release the pedal slower, then the noise lasts a little longer, maybe 30% longer. However, it is still a mere fraction of a second.

The occurence of the noise seems to be completely random. I don't have to be boosting for it to occur. Sometimes the car will do it for about 5 minutes, then the rest of the journey the noise won't be there. Sometimes it won't do it at all. I can't really put a pattern to it. Also, last time at the shop when they were doing work on the car, they were pushing the throttle from under the hood for testing purposes. This did not make it squeak at all. Unfortunately, as I said, sometimes it doens't squeak anyway. So, it is hard to tell if it didn't squeak because the noise is related to just the pedal assembly, or if it didn't squeak because it didn't "feel" like it. I have a feeling it should have squeaked because they did it maybe 10 times over the course of 2 hours.

Anyway, does anyone have any idea as to what it might be? I was thinking here is a possible relation to the throttle body elbow, because it is related to the throttle. Thanks for any opinions.

 

[PogiTSI]

how loud is it??? do you smell any Burning?? check all ur belts, Im sure uve done. It may be something binding up on the throtel Cable. I dont know to much on the mechanics between the Peddle and the TB. there might be a worn Bushing somewhere between.

 

[thehyena]

you sure it's not your bov?

 

[CowPimp]

I'm pretty sure it's not my BOV. I don't have to be boosting for the noise to occur, and I don't vent to the atmosphere.

I haven't checked any belts, I don't really know how to go about that (I know a little about cars, but I am a moron when it comes to actual work on them). If you consider looking at the belts spinning and saying, "Yep, they're spinning," then yes I have checked them. There is no smell or driveability problem. I'm hoping it's something simple in the pedal assembly that could just be fixed with some good old WD40 or other lubricant. Also, it seems to be occuring less and less lately. The noise seems to be getting quieter too...

It's quiet enough that I cannot hear it at all with my windows up. Also, the music has to be playing below my normal listening level (Which is above average, but not excessively loud) to be able to hear it.

 

[PogiTSI]

hmm, Then I would guess its comming from the inside of ur interior. It could be the Return spring on the Peddle? When ur car is off, look at the belts. Are there Cracks, Worn Teeth. I would Suggest getting ur timming belt looked at if it hasnt been Changed Recently. Get some Lube and lube up some Joints on the Peddle Assembly, It couldnt hurt.

 

[CowPimp]

Lubing the pedal assembly was the next thing I was gonna try. My timing belt was changed 26K ago, I don't think it should be wearing out yet. I plan on changing it a little under 60K, maybe 55K. I will definitely check out the other accessory belts though. Thanks. Keep any guess coming though!

 

[Luke223]

I have a similar noise. If I let off the gas just before boost at about 3K RPM’s I hear this kind of chirp. I believe it is the waste gate just starting to open and causing a slight air vibration noise that resonates. It started right after I upgraded my turbo. At first I thought it was a problem with the turbo bearing or a metal on metal rubbing of the turbine wheel, but after creating the noise at will and doing several WOT pulls I have come to the conclusion it is just a very tight sealing wastegate.

Luke

 

[TSiAWD666]

The noise doesn't correlate to a specific RPM does it? I get something similar when I rpms are decreasing without gas through the range around 2000 rpm. If I'm coasting in gear and I sit at that rpm range for a little the groan/squeal will be extended.

 

[CowPimp]

Nope. It only happens as I lift the pedal up. I'm hoping some lubricant will take care of it. However, it will be a few days before I can really toy with it. I have a really busy week. If anyone has any other ideas, I would love to hear them. I'll be sure to try everything that is mentioned to me.

 

[PogiTSI]

I would have said ur BOV too, but they said They opend the hood and couldnt hear it. Its probly nothing important. Loud sounds are usualy bad signs. but no worrie, your car runs fine, so I wouldnt worrie about it. Lube up the peddle assembly and holla back, WOO WOOO!

 

[CowPimp]

Oddly enough, I've only heard the noise a couple of times today. Also, it seems to be getting quieter. I'm thinking there is some part that needed a "breakin" of some sort. I don't think I even need to lube the pedal assembly if it keeps going like this. Thanks for all your help. I'll come back with updates if anything changes.

 

[kevingst]

I hate to add this, but that sounds EXACTLY like what my bov does. Under boost it's the sound we all know and love. But if I'm just giving it a little gas and let off slowly just before boost starts to build, it sounds more like a metallic whistling noise. Sometimes if I do it just right I can prolong it for a good 2-3 seconds...that really confuses my passengers. Anyway, just thought I'd add that to try and lighten any worrying.

 

[CowPimp]

Hrm, it is possible that's what it is. I wasn't really hearing the noise for a while, but then it came back. It probably has to do with the way I'm driving and that is why it's completely random; sometimes I drive the car harder than other times without really thinking about it (Probably depends on the music I'm playing). I did get a 1G BOV around the time that it started occuring, so that is a definitely possiblity.

I try not to boost to save gas, but I accelerate as much as I can without boosting. So, most often I am accelerating very close to the point of boost without boosting. I really hope that's what it is. That would also explain why the noise was non-existant when the hood was popped at the shop and the car was being reved in neutral. Also, the noise is slightly prolonged if I release the pedal slower. It just happens most often when I shift gears, so the pedal comes up quick and therefore the noise is quick. The lubing of the pedal assembly did nothing. I expected it not to, because the noise definitely is coming from outside.

I'm going to try and practice releasing just right so that there is a long lasting metallic whistling noise so that I can confuse my passengers too. This will also help me determine if it is actually the BOV making the noise. Thanks.