Straight pipe Popcorn popping at 5mph

[DenaliRich]

So I went with removing stock muffler and put straight pipe. Sounds awesome. The ONLY drawback that I never saw anyone put was the random loud popping when no foot on gas rolling around 4-7mph. Not like the back flow with an aftermarket muffler. It’s loud and sounds kinda crappy but it doesn’t always do it. I can count on it in my neighborhood as I go down hill. Neighbors always look like wth is up with that new Denali??? I also had the valve before the muffler removed when I did it. So I was gonna just replace it with an expensive borla when I saw someone talk about covering the 6 baffles by the tail pipe to give the exhaust a deeper sound. I tried it to see if it would stop the popping. Nope, still there just a little deeper pop.
 

Anyone know of a way to stop this?

Or do I have to put a muffler back on?

 

I have video of start up with and without the baffles covered. Can’t really tell a difference. And the videos won’t upload. 

[M1ck3y]

I'm assuming its because of dfm. Disable dfm, install stock exhaust, or install aftermarket exhaust. 

[Jac365]

I'm thinking it's decal burble from downshifting. My Borla cat back makes it sound like more of a growl than a pop.

[chadman]

On 6/26/2020 at 8:56 PM, M1ck3y said:

I'm assuming its because of dfm. Disable dfm, install stock exhaust, or install aftermarket exhaust. 

DFM would not be working at 4-7 mph. Always an issue with straight pipe. All depends on the particulars and all vehicles are different. A resonator may help.

[M1ck3y]

13 hours ago, chadman said:

DFM would not be working at 4-7 mph. Always an issue with straight pipe. All depends on the particulars and all vehicles are different. A resonator may help.

Compared to Active Fuel Management, which alternates between eight- and four-cylinder modes, DFM features 17 cylinder patterns. That greater authority over cylinder patterns constantly to optimize efficiency and power delivery at all speeds.

 

https://gmauthority.com/blog/gm/general-motors-technology/general-motors-propulsion-technology/general-motors-dynamic-fuel-management-cylinder-deactivation-technology/

 

I've never heard of popping at that speed, even straight piped. A high end cat back is actually louder, and sounds better. If you loping around picking your nose, I have no doubt gm would have programmed less then 8 cylinders.

Edited June 30, 2020 by M1ck3y

[chadman]

16 hours ago, M1ck3y said:

Compared to Active Fuel Management, which alternates between eight- and four-cylinder modes, DFM features 17 cylinder patterns. That greater authority over cylinder patterns constantly to optimize efficiency and power delivery at all speeds.

 

https://gmauthority.com/blog/gm/general-motors-technology/general-motors-propulsion-technology/general-motors-dynamic-fuel-management-cylinder-deactivation-technology/

 

I've never heard of popping at that speed, even straight piped. A high end cat back is actually louder, and sounds better. If you loping around picking your nose, I have no doubt gm would have programmed less then 8 cylinders.

This is generic info from a press release; in the world of the average person and for media purposes, it works at "all speeds".   That is not technically correct. I work in the business, and have for 20 plus years.  For DFM to set any codes, these are the conditions:

• Cylinder Deactivation = Enabled
• Engine = Running
• Ignition Voltage = Greater than 11 V
• Throttle Position Sensor = Less than 6%
• Vehicle Speed = Greater than 25 km/h (15.5 MPH)

This means you have to be above 15mph for the system to be active and monitoring data. So, as mentioned, DFM is not active at 4-7 mph. DFM active at such slow speeds would make it a bucking bronco.