Digital Tuning 1991-exhaust crackles

paddyrk

Member
Jun 7, 2018
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Dublin, OH
Hello all,

I have a 1991 347 stroker lx 5.0 with the HP EFI system. I have an off-road X-pipe with shorty headers, full tail pipes, and mufflers. I would like to know how to do exhaust pops and crackles, such as when I let off the throttle after acceleration. I have not had any success with this so far, but if anybody has any information on how to do this, I would love to hear about it.
 
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kendawg73

5 Year Member
Feb 5, 2014
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Hello all,

I have a 1991 347 stroker lx 5.0 with the HP EFI system. I have an off-road X-pipe with shorty headers, full tail pipes, and mufflers. I would like to know how to do exhaust pops and crackles, such as when I let off the throttle after acceleration. I have not had any success with this so far, but if anybody has any information on how to do this, I would love to hear about it.

why on earth would you want the exhaust to pop and crackle?
 

kendawg73

5 Year Member
Feb 5, 2014
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I have had exhaust leaks multiple times before and also heard crackles and pops multiple times before, and can easily tel the difference, as they do not sound very similar.

I put the Roush mufflers on my daughters 2011 and it does that... if you wind out the gears and got to shift to the next one, it will do the popping... I hate it... lol... I try my best not to make it do it....

I"m thinking it has something to do with the way the newer motors are I guess... since I don't recall the push rod 302's doing this... plus I don't really care for the sound the newer motor make any way... love the old school sound of the push rod motors...
 
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Mustang5L5

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Feb 18, 2001
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The crackle on decell is unburned fuel being ignited in the exhaust. It's also caused by exhaust leaks allowing o2 into the exhaust...which allows unburned fuel to ignite.

How to replicate it? Create and exhaust leak and/or set your fuel mixture a little rich.
 

paddyrk

Member
Jun 7, 2018
69
4
18
53
Dublin, OH
The crackle on decell is unburned fuel being ignited in the exhaust. It's also caused by exhaust leaks allowing o2 into the exhaust...which allows unburned fuel to ignite.

How to replicate it? Create and exhaust leak and/or set your fuel mixture a little rich.
Ah okay, that makes sense, so I would need to get some source of o2 into the exhaust without messing up my o2 sensor, as my ECU already runs it rich.
 

kendawg73

5 Year Member
Feb 5, 2014
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The crackle on decell is unburned fuel being ignited in the exhaust. It's also caused by exhaust leaks allowing o2 into the exhaust...which allows unburned fuel to ignite.

How to replicate it? Create and exhaust leak and/or set your fuel mixture a little rich.

Well in most cases, yes, but here are some examples... my daughters car (2011), has no exhaust leaks, and nothing else was done to it but remove stock mufflers (so car is not running rich) and install the Roush ones (btw one of the easiest damn installs I have done, since the mufflers are at the very back, 2 bolts on each, bamn done...) I think the more free flowing mufflers cause air to go back or something, or maybe the stock ones kinda muffle that popping...

example 2, my bike (v-twin cruzier) will do it on decel with the after market exhaust... (100% no leaks)... the way I got that to stop doing it, is adding fuel (richen it up)when the throttle is @ 0% and in the 2000-500 or 3000-500 rpm range (forget which, but when I'm off the throttle and engine breaking) but that stops the popping on decel.. again, it's the more free flowing exhaust that caused it, with the stock exhaust you never heard it...
 
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