Popping sound? (video inside!)

[BenMTL]

Guys, turn up your speakers and listen to this....

http://tinypic.com/player.php?v=n52d...9#.Vpfk7U3SmHs

What the **** is that sound? Been happening for a while now, but never this loud....A friend litterally thought I had someone banging in my trunk...Sounds just as loud from the inside.

Used to happen only when I was low on fuel (1/4 or below) but now it happens even with a half tank of gas. Also only happens when stopped/idling...

Any ideas?

[BenMTL]

80 views but nobody knows what this sound is?

Any guesses or ideas what to do next?

No way mine could be the only b7 in the WORLD that does this

[mtroxel]

Ben, I really can't hear the sound. Sounds like the motor is running, but I don't hear a popping sound. I'd bet no responded cause they don't hear it either.

[BenMTL]

Thanks for the reply Mtroxel but it is 100% there....Turn up your speakers and listen again

3 or 4 distinct popping or knocking sounds coming from the back of the car where I am filming from (rear passenger wheel) and the sound is distinctly different and separate from our normal engine sound.

[swaggerwagon]

I heard the sound but it's really hard to tell. Try filming from inside the cabin. Mine makes a popping sound which I attribute to two things: Spare/jack not being properly secured and cold weather means the exhaust is gonna rattle more. My exhaust definitely rattles more when its <30*

[mtroxel]

Ben nobody loves you more than I do. Turned my speakers up all the way, twice.

Every now and then I hear something, but I think you hear it because you know what it sounds like. If you listen to that video your ears don't know what to hear. I'm just not hear'n it!

[BenMTL]

Hahahah, thanks mtroxel....That's true...I'll try recording from the inside so all the other noises are drowned out

Definitely not jack stand as car is still and I have nothing in my trunk so it's not the content of it shifting around either....I also thought it is might be my exhaust BUT, if you could notice the noise, it is not a high pitched "metallicy" sound but rather a very low bitch "boom" or "knock" sound so......

[swaggerwagon]

Hahahah, thanks mtroxel....That's true...I'll try recording from the inside so all the other noises are drowned out

Definitely not jack stand as car is still and I have nothing in my trunk so it's not the content of it shifting around either....I also thought it is might be my exhaust BUT, if you could notice the noise, it is not a high pitched "metallicy" sound but rather a very low bitch "boom" or "knock" sound so......

Your car doesn't have to move to make the sound. Mine doesn't. I never said it was metallic sound. Food for thought.

[Older_not_Wiser]

It almost sounds like you are getting an occasional combustion in your exhaust/muffler. Almost like a very subtle backfire.

You say it only does it at 1/4 tank (now 1/2 tank), so that would make the above seem not likely. Only other thing I can think of is, there has to be some way for air to be able to get back in the gas tank as gas is used. If there were some restriction to that air path into the gas tank and it were gulping the air back in when there was a little vacuum in the gas tank, the tank may resonate a bit with that gulp. Try putting your hand on the muffler or gas tank when it is making that sound and see if you feel anything.

Perplexing. Let us know if you find what it is.

[clumsyme]

I get this same popping sound!!! I thought I was crazy. I usually get it when the car is under 1/3 tank and I can hear it idle at a stop light sometimes or right after I turn off the car in the garage I will get 3-5 pops within 10 seconds after turning the car off.

I am going to be changing my LPFP next week do to a stalling issue when I start the car when the car is up to temp but has been sitting for 10-20 mins. I was thinking they were related.

[BenMTL]

Finally!!!! Yay I'm not alone....

OK, I think it is also fuel related given it never happens my when tank is 3/4 or 4/4 full....HOWEVER, EVAP related NOT LPFP....I have my factory LPFP but I did replace my LPFP controller 6000 miles or so again. Sound was there before and after.

First time in my life I had trouble filling up gas with this car? Yesterday.

That is a common problem with these cars, just never thought it would happen to me....But when it does, people say the pump clicks even when not full (exactly whats happening to me now) and they say EVAP system was the problem so I'm going to investigate that now...

[mtroxel]

I was thinking later, I can't hear the sound but if it's in the back while the car is stationary, it's either the fuel pump, or something bubbling in the EVAP. I was going to ask if you've ever had trouble filling the tank.

I think you need to reach under there with a stethoscope while the sound is happening, and touch the EVAP canister under the trunk.......see if that, or some other part of the EVAP system, is the source.

[BenMTL]

Funny enough....Just bought a stethoscope the other day to track some some clatter in my engine bay...

Isn't the EVAP canister under the cap though? Specifically, under that round plastic cover under the car? The problem (sound) has been going on for 1-2 years but I only recently have trouble filling up my tank (this week).

Not exactly sure if the 2 are related but hopefully they are and I can kill 2 birds with 1 stone...

While I have your attention mtrox, check out this other post I need your help with?

http://www.audizine.com/forum/showth...1#post11326890

Shameless I know...

[mtroxel]

Isn't the EVAP canister under the cap though? Specifically, under that round plastic cover under the car? The problem (sound) has been going on for 1-2 years but I only recently have trouble filling up my tank (this week).

Under the round cover below the spare tire.

[BenMTL]

Thanks as always mtrox!

Yep, thought so....Found a new EVAP box for $50 + shipping though with OEM part number so I might just buy new instead of trying to take apart and clean the system

People say this box normally sells for $200-300 so then I would have definitely tried that instead, but like this....

[clumsyme]

I wonder if a clogged evap is what is causing an issue in my car.....

If the tank cant let air in as fuel leaves causing a vacuum leading the fuel starve but I dont that it could create enough vacuum to fight the fuel pump.

I have a CIS mk1 caddy and it has less fueling issue than my B7.......