Strange Popping Noise...

I�fm reposting this topic to this forum in hopes of getting a few more inputs than I did on the Tech forum.

AZ Outlaws wrote:

Some times, not often, when I pull up to a stop light and am sitting there, I hear a single "pop" kind of noise. Sometime it is loud other times faint. It can also be felt and seems to come from behind me and below the floorboard. It only happens after I've come to a full stop and have been sitting there a short time. Has anyone else experienced this? I hope this is not going to be one of those things the dealer said he can't duplicate. Thanks for any inputs.

Ed�fs reply matches the exact problem I�fm having:

AZ: I am on my first trip with my Crossfire from NC to Fl. and I have experienced the noise you talked about and was searching this site to see if anyone else has. It comes from the back, is a thump as if someone has driven into me. My wife has experienced it also. It only happens when stopped such as at a red light and is very upsetting. If no one can give me a good explanation, I will take it back for a check when I return.

This problem is not from window popping or from the few ideas some of you posted to the original post. It almost seems like a single backfire kind of noise.

Thanks again for any further inputs or suggestions. :?: :?: :?:

_____________________
'04 Coupe SSB 6-Speed #02815
Crossfire International (XFi)Charter Member
Lights on... Wings up... Let's go!!!(It's A Hook-Up Thing)
"Left Coast Hook-Up" Survivor... May 15, 2004
"Malibu Canyon Hook-Up" Survivor... Jul 17, 2004
"Phoenix Ice Cream-Up" Survivor... Jul 31, 2004
"LV Aw Shucks-Up" Survivor... Aug 21, 2004

 

Mine does the same thing! Took it to the dealer and they found nothing. The noise is very faint, but if the radio is off you can hear it. sounds like it is coming from the floor behind the seat??????????
Just turn the radio up and iam happy

 

Have the same popping noise. Also had it in my 2003 SLK. MB dealer could never find it either.
It almost sounds like a small relief or "pop-off" valve opening.

 

Exactly... mine stopped doing it for awhile, now it's back every so often. Haven't mentioned it to my dealer. My guess it will be one of those things you live with... thanks for your input, at least Bob Brown are not alone. :wink:

Anyone else have this noise since this thread was first posted????

_____________________
'04 Coupe SSB 6-Speed #02815
Crossfire International (XFi)Charter Member
Lights on... Wings up... Let's go!!!(It's A Hook-Up Thing)
"Left Coast Hook-Up" Survivor... May 15, 2004
"Malibu Canyon Hook-Up" Survivor... Jul 17, 2004
"Phoenix Ice Cream-Up" Survivor... Jul 31, 2004
"LV Aw Shucks-Up" Survivor... Aug 21, 2004

 

Mine does the exact same thing! I was thinking it's my spoiler seating or soemthing like that...

 

It only pops after coming to a complete stop, I would think the spoiler would be completely retracted by then??? Any of the CrossFire techs hear anything on this or have any inputs???

_____________________
'04 Coupe SSB 6-Speed #02815
Crossfire International (XFi)Charter Member
Lights on... Wings up... Let's go!!!(It's A Hook-Up Thing)
"Left Coast Hook-Up" Survivor... May 15, 2004
"Malibu Canyon Hook-Up" Survivor... Jul 17, 2004
"Phoenix Ice Cream-Up" Survivor... Jul 31, 2004
"LV Aw Shucks-Up" Survivor... Aug 21, 2004

 

Hmm... I will have to "pay attention" (i.e., turn the stereo down) tomorrow and see if I hear it too.

Okay... for troubleshooting purposes, if you ARE hearing this noise, might want to post your:

1) VIN
2) tranny
3) tires

see if we can unscientifically develop a trend... two of four reports are known to be manual's, and those two have VIN's widely separated. The other two reports we have no data.

 

I have the popping noise when I stop sometimes, doesn't really bother me, just curious what it is. Almost sounds like it's coming from the passenger side, just behind the passenger door, somewhere over there. And for David Burns, my vin is listed below, it's auto, and i have the continentals.

 

The only noise I hear at times (when I have 3/4 tank of gas or less) sounds like a poping noise but it is actually "fuel slosh" behind the seat. It's more prevelant and louder when the fuel level is around 1/2 tank.

 

For what its worth...
Not the tires...had Michelin Pilot Sports on the SLK...Contis on the Crossfire...
Tested the fuel slosh issue in the SLK...it wasn't that either...unless there is some sort of float in there, but I only hear the noise on a warm engine anyways...not on a cold one...
SLK was autostick, Crossfire is 6 speed manual...
Catalytic converter expansion/contraction???
Definitely not the spoiler...SLK doesn't have one...

 

In mine it sounds like there's something solid hitting the inside of the tank. But, it's wave action that's slapping the inside of the tank.

In yours, I don't have a clue what it may be. The fact that it only does it only after it's been running and is warmed up lends me to think maybe the exhaust or Cat. ?!?! Maybe and exhaust hanger or something?

Good luck and please let us know when you get it figured out.

 

I'm getting some popping, but it seems to be maybe trim panel flexing around the passenger side near the bulkhead. Sometimes behind the drvier's seat too. :? Driving me alittle nuts. So much for the X-fire's super rigid chassis? Hope not.




Dallas

 

Could be the fuel regeneration solenoid for the evaporative emissions system. Now, the next question, what the heck is that? With the new emissions laws, there is a charcoal canister in every car sold in the USA. In the Crossfire, this is mounted under the vehicle, directly under the fuel tank. This would place it near where you are hearing the noise.

The comments about only hearing it when the engine is warm and upon coming to a stop would make sense, since this is when there is the most fuel traveling in the system. Also, since the system is closed loop, fuel is always flowing back to the tank from the fuel rail. When stopping, the fuel pressure takes a while to drop back down to engine idle loading. As a result, the purge solenoid ramps up to return the excess to the tank.

Most cars will make some dull popping sound when this solenoid activiates (usually, from underhood). It is probably louder on the Crossfire since the tank is located so near the driver's ear. No cause for concern. By the way, you should feel good about saving the environment when you hear it!

Hope this wasn't too techie! Thanks. :roll:

 

Thanks for the input... where and how did you come by this inforamtion and is there anything we can do to quite the noise as it is very annoying?

_____________________
'04 Coupe SSB 6-Speed #02815
Crossfire International (XFi)Charter Member
Lights on... Wings up... Let's go!!!(It's A Hook-Up Thing)
"Left Coast Hook-Up" Survivor... May 15, 2004
"Malibu Canyon Hook-Up" Survivor... Jul 17, 2004
"Phoenix Ice Cream-Up" Survivor... Jul 31, 2004
"LV Aw Shucks-Up" Survivor... Aug 21, 2004

 

I know from my old SLK days and crawling under the car. The whole fuel pump unit is covered by a detachable shield. If the noise is really annoying, you could try asking the dealer to see if all of the fuel lines are still in their isolators under the body. Something might have worked loose. Good luck. :?

 

I'm not hearing any pops. Either "tomorrow" or since.

 

Oliver, Thank you for the tip. I feel a lot better.

 

http://www.slk32.com/pages/fuelthump/fuelthump.html

Problem: Clunking, knocking, clicking behind the passenger seat.

There is a common issue with most SLK 320s and SLK 32 AMG cars.
This related to the fuel and emission control systems in these cars.
There is an emissions valve located behind the passenger seat that can make a clicking, thumping or knocking noise.
This noise is best heard when the car is at a complete stop and the top is closed.
This issue is normal but some earlier 320s can have this valve updated to reduce its occurance.
The service bulletin # is 103/P-B 47.30/15 Shut Off Valve
Also may go by this number : 47/3045


Problem: Rough idle.

If your idle is rough in the 320 it could be the engine ECU.
It can be replaced with an updated unit.
The Service Bulletin # is 121/P-BB0765/14 ECU Update
Also may go by this number: PB07-65/14

 

 

My dads new Kia Optima was also making a sound like you guys are describing. This may not help you, but, when we looked in the trunk, we found the squirrels had gotten out of their cages!! :shock: