does your car say "boom"?

Rum · 04-15-2008, 08:24 AM

I've never heard this in any other car that I have owned. Every time I lift off the throttle, about a half second later I hear a soft but very noticeable "boom" coming from the back of the car. I'm assuming it's from the exhaust, and I'm guessing it has something to do with changes in back pressure, maybe related to the turbo spinning down or something...

Do you hear the same sound and any idea what it is?

Spork · 04-15-2008, 08:28 AM

Afterfire?

Rum · 04-15-2008, 09:09 AM

Let me clarify it sounds like a subwoofer going "boom," not an explosion. And it is soft.

***snorky*** · 04-15-2008, 09:34 AM

i'm going to go with rear diff dance aka rear diff clunk. I assume you're talking about shifting while running through the gears at WOT?

Rum · 04-15-2008, 09:47 AM

Quote:

Originally Posted by snorky

i'm going to go with rear diff dance aka rear diff clunk. I assume you're talking about shifting while running through the gears at WOT?

Happens even when not shifting, and does not have to be WOT. Just a lift off of the gas after having been on the gas. I only notice it when on the freeway, it might not happen at low speeds.

Oh also you don't have to take it out of gear. Just let the throttle plate close, and a half second later, one low-frequency "woomp" from the back.

At first I thought it was just exhaust sound resonating in the hatch area.

TheAn$wer · 04-15-2008, 09:48 AM

backfiring...

Edit: Didnt notice it was stock, nvm!

**Digitalfiend** · 04-15-2008, 09:49 AM

There is usually enough slack in the drivetrain when you liftoff the gas that you can hear all sorts of noises. If it isn't too loud, I wouldn't worry about it. I don't think I've heard this from my '08.

Real Deal · 04-15-2008, 09:53 AM

i get this when my rear diffs aren't warmed up. im not sure how else to describe it

Joel-STi · 04-15-2008, 10:19 AM

I've noticed it also. Slight low rumble when lifting off the throttle.

polyol · 04-15-2008, 10:31 AM

Is there any chance it could be the BOV...

flatthump · 04-15-2008, 10:33 AM

It is play in the driveshaft u-joints, tranny, and rear diff.

Rum · 04-15-2008, 10:34 AM

Quote:

Originally Posted by polyol

Is there any chance it could be the BOV...

Good Q - The stock BOV dumps into the exhaust system somewhere downstream of the turbo, right? My FI knowledge is very limited...

flatthump · 04-15-2008, 10:36 AM

Quote:

Originally Posted by Rum

Good Q - The stock BOV dumps into the exhaust system somewhere downstream of the turbo, right? My FI knowledge is very limited...

No, that's the wastegate

the BPV vents back into the turbo inlet pipe.

Lurker · 04-15-2008, 11:01 AM

slight backfire type noise most likley.

Joel-STi · 04-15-2008, 11:03 AM

Mine sounds drivetrain related to me. Could be wrong though.

04-15-2008, 08:24 AM	#1
Rum Junior STI Driver Car: DGM 08 STI Fav Mod: Proudly mod-free since 2008 Location: Southern CA Posts: 106 Join Date: Mar 2008 Trader Rating: (0)	does your car say "boom"? I've never heard this in any other car that I have owned. Every time I lift off the throttle, about a half second later I hear a soft but very noticeable "boom" coming from the back of the car. I'm assuming it's from the exhaust, and I'm guessing it has something to do with changes in back pressure, maybe related to the turbo spinning down or something... Do you hear the same sound and any idea what it is? This ad is not endorsed by this member. Please register or login to hide this ad.

04-15-2008, 08:28 AM	#2
Spork Silver Member Car: AW 08 STi Fav Mod: snow tires Location: Waltham, MA Posts: 175 Join Date: Dec 2007 Trader Rating: (0)	Re: does your car say "boom"? Afterfire?

04-15-2008, 09:09 AM	#3
Rum Junior STI Driver Car: DGM 08 STI Fav Mod: Proudly mod-free since 2008 Location: Southern CA Posts: 106 Join Date: Mar 2008 Trader Rating: (0)	Re: does your car say "boom"? Let me clarify it sounds like a subwoofer going "boom," not an explosion. And it is soft.

04-15-2008, 09:34 AM	#4
*snorky* killer ants in your pants Car: OBP05MURDEREDOUTFTW Fav Mod: Fullerton's Qrack on my car Location: Chicagoland Posts: 3,375 Join Date: Apr 2006 Trader Rating: (21)	Re: does your car say "boom"? i'm going to go with rear diff dance aka rear diff clunk. I assume you're talking about shifting while running through the gears at WOT?

04-15-2008, 09:48 AM	#6
TheAn$wer Professional STI Driver Car: SGM '06 ReX Fav Mod: Boxer Rumble! Location: Modesto, CaLi Posts: 479 Join Date: Sep 2004 Trader Rating: (3)	Re: does your car say "boom"? backfiring... Edit: Didnt notice it was stock, nvm! Last edited by TheAn$wer : 04-15-2008 at 10:00 AM.

04-15-2008, 09:49 AM	#7
Digitalfiend Super Moderator Car: 08 DGM STI Fav Mod: My wife :) Location: Brooklin, Ontario Posts: 5,062 Join Date: Oct 2003 Trader Rating: (0)	Re: does your car say "boom"? There is usually enough slack in the drivetrain when you liftoff the gas that you can hear all sorts of noises. If it isn't too loud, I wouldn't worry about it. I don't think I've heard this from my '08.

04-15-2008, 09:53 AM	#8
Real Deal STI Driver Car: 06 WRX Limited Fav Mod: Removal of DRL Location: Seatown Posts: 287 Join Date: Oct 2006 Trader Rating: (0)	Re: does your car say "boom"? i get this when my rear diffs aren't warmed up. im not sure how else to describe it

04-15-2008, 10:19 AM	#9
Joel-STi Amateur STI Driver Car: Silver 08 STi Fav Mod: AP Stage 1 Location: 39.5° N 119.86° W Posts: 39 Join Date: Feb 2008 Trader Rating: (0)	Re: does your car say "boom"? I've noticed it also. Slight low rumble when lifting off the throttle.

04-15-2008, 10:31 AM	#10
polyol Spec C Club Car: 04 STi Fav Mod: Motor Mounts Location: Eugene Posts: 2,183 Join Date: Oct 2004 Trader Rating: (0)	Re: does your car say "boom"? Is there any chance it could be the BOV...

04-15-2008, 10:33 AM	#11
flatthump Enginerd Car: The Spaze Mobile Fav Mod: Tuning Location: South O.C., Ca Posts: 12,636 Join Date: Jan 2006 Trader Rating: (5)	Re: does your car say "boom"? It is play in the driveshaft u-joints, tranny, and rear diff.

04-15-2008, 11:01 AM	#14
Lurker Senior STI Driver Car: 07 STI UGM Fav Mod: Boob jobs Location: San D'ego Posts: 356 Join Date: Mar 2007 Trader Rating: (6)	Re: does your car say "boom"? slight backfire type noise most likley.

04-15-2008, 11:03 AM	#15
Joel-STi Amateur STI Driver Car: Silver 08 STi Fav Mod: AP Stage 1 Location: 39.5° N 119.86° W Posts: 39 Join Date: Feb 2008 Trader Rating: (0)	Re: does your car say "boom"? Mine sounds drivetrain related to me. Could be wrong though. This ad is not endorsed by this member. Please register or login to hide this ad.