Crackling Exhaust Sound? - Ford Mustang Forum
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post #1 of 21 (permalink) Old 07-24-2006 Thread Starter
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Talking Crackling Exhaust Sound?

When I start up my 06 GT in the morning, the exhaust makes a crackling and popping kinda sound whenever I let the RPMs fall. This is seriously the coolest exhaust sound I've ever heard, EVER!! It sounds powerful, like the car just wants to unleash hell onto the street!!

The only problem is, it goes away once the car warms up. Why does it do this, and is there any way I can make it sound like that all the time?? Can it be done with a tuner, for instance?
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post #2 of 21 (permalink) Old 07-24-2006
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Pretty sure back-pressure causes it. Engine sucking air backwards through the exhaust. It's a cool sound and isnt harmful. I know I can usually get that sound even the RPMS are coming down from a take-off . Obviously you can only have that sound when there isn't much exhaust flowing out the pipes.

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post #3 of 21 (permalink) Old 07-24-2006
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Actually it has nothing to do with backpressure but rather the combination of ignition timing and air:fuel ratio. When the coolant is at less than normal operating temp the AFR is richer to prevent stalling, ie. the same effect as a choke in a carburetted engine. When you release the throttle fuel flow is shut off until the engine enters the RPM range controlled by the idle system at which point fuel flow starts and this richer mixture ignites in the exhaust system and you hear the popping. The engine could be tuned to do this all the time by raising the RPM at which fuel flow begins on coastdown, enriching the mixture, and retarding the timing. However this would increase emissions substantially with no benefit other than the amusement factor so I doubt any tuner would do it.
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post #4 of 21 (permalink) Old 07-24-2006
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I get that sound everyday with my Flowmasters...even when the engine is hot!!

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post #5 of 21 (permalink) Old 07-24-2006
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ohhh yeaa.. I love that popping and crackling sound, for that reason I always hit the throttle once or twice on cold starts . If the Flowmasters do that at all times I think I'm gonna have to get me some Flowmasters lol. However, from what I've heard they aren't much louder than stock at idle, am I right?

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post #6 of 21 (permalink) Old 07-24-2006
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Quote:
Originally Posted by vantage
ohhh yeaa.. I love that popping and crackling sound, for that reason I always hit the throttle once or twice on cold starts . If the Flowmasters do that at all times I think I'm gonna have to get me some Flowmasters lol. However, from what I've heard they aren't much louder than stock at idle, am I right?
At idle when the car is cold they are lowder. At idle when the car is warm they are about the same, although the Flows have a deeper sound. Any other time they are nothing alike.

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post #7 of 21 (permalink) Old 07-24-2006
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Quote:
Originally Posted by scramblr
I get that sound everyday with my Flowmasters...even when the engine is hot!!

Ditto what he said

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post #8 of 21 (permalink) Old 07-25-2006
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Man do I love that morning crackle. I am told that Ford Engineers intentionally programmed this in. The crackle is basically unburned fuel igniting in the Manifolds. It should be easy to tune this out. This leads me to believe that the rumor may be true.

Carbureted cars have a tendency to do this as fuel will continue to trickle in when you let off the accelerator. I am told Ford engineers were looking to bring back the old mustang sound

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post #9 of 21 (permalink) Old 07-25-2006
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If you guys really like that sound you need to get some Loudmouths. You have no idea what you're missing. I paired mine up with a Magnaflow catted X-pipe and I love it. Hearing-impaired beware!
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Quote:
Originally Posted by ChestyP79
If you guys really like that sound you need to get some Loudmouths. You have no idea what you're missing. I paired mine up with a Magnaflow catted X-pipe and I love it. Hearing-impaired beware!
Well there is good sounding loud, and then there is over-the-top, obnoxious, 'my ears are bleeding' loud, I would rather have the former.

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I had a Supra Turbo with AEM programable engine management system. I could tune the "backrap" to anywhere from almost nonexistent to flames exploding out the pipe by varying ignition timing, injector duty cycle, and fuel shutoff RPM. That is beyond the capability of the handheld tuners like SCT and Diablo, at least insofar as enduser-adjustable parameters.
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I also love that start up crackle! Although aftermarket exhausts usually sound more aggressive, I must tip my hat to the Ford engineers. They got the sound just right, IMHO. Loud enough to sound nice, but not annoying. Just the right tone, as well. However, quiet on the highway, with no irritating drone. I'm sure they worked on intake/exhaust combinations for a long time to achieve this signature sound that you can't mistake for anything else but a Mustang.

I've also enjoyed this nice crackling/burbling sound when coasting in 2nd and 3rd gear between 2500-1500 RPM's. Unfortunately, I only hear it when the weather's cool, and I have the windows down. In Florida where I am, I'm forced to run with the windows up and the A/C blasting for most of the year. No way to enjoy this nice motor music under those circumstances....

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Quote:
Originally Posted by rainman
I also love that start up crackle! Although aftermarket exhausts usually sound more aggressive, I must tip my hat to the Ford engineers. They got the sound just right, IMHO. Loud enough to sound nice, but not annoying. Just the right tone, as well. However, quiet on the highway, with no irritating drone. I'm sure they worked on intake/exhaust combinations for a long time to achieve this signature sound that you can't mistake for anything else but a Mustang.

I've also enjoyed this nice crackling/burbling sound when coasting in 2nd and 3rd gear between 2500-1500 RPM's. Unfortunately, I only hear it when the weather's cool, and I have the windows down. In Florida where I am, I'm forced to run with the windows up and the A/C blasting for most of the year. No way to enjoy this nice motor music under those circumstances....
When I'm driving home from work I don't care if I get sweaty so I shut the radio off, roll down the window, and enjoy the rumble.
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Quote:
Originally Posted by 65sohc
When I'm driving home from work I don't care if I get sweaty so I shut the radio off, roll down the window, and enjoy the rumble.
I work in a hot azz pant shop so Im already hot and I too enjoy the sound

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Quote:
Originally Posted by rainman
I also love that start up crackle! Although aftermarket exhausts usually sound more aggressive, I must tip my hat to the Ford engineers. They got the sound just right, IMHO. Loud enough to sound nice, but not annoying. Just the right tone, as well. However, quiet on the highway, with no irritating drone. I'm sure they worked on intake/exhaust combinations for a long time to achieve this signature sound that you can't mistake for anything else but a Mustang.

I've also enjoyed this nice crackling/burbling sound when coasting in 2nd and 3rd gear between 2500-1500 RPM's. Unfortunately, I only hear it when the weather's cool, and I have the windows down. In Florida where I am, I'm forced to run with the windows up and the A/C blasting for most of the year. No way to enjoy this nice motor music under those circumstances....
Yea they did do an amazing job on the exhaust which sometimes makes me think that an aftermarket system isn't really needed, but then I hear these ppl going on and on about how good their aftermarket mufflers sound and I convince myself that I need them!

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