Sputtering while coasting

[Cschwartz]

While driving my 2014 Silverado, I never have a problem if I accelerate quickly. However, there has been skipping/sputtering when I coast or slowly accelerate. This is not a clicking, loud knocking sound like I see most describe on here... Anyone have any idea what it could be?  Thanks in advance! If needed I can try and video the sound later on today.

[Ryan McGrath]

Need more info on the noise i.e.... what speed where is the noise front, rear? does it do this everytime... is your MPG suffering ? 

[Cschwartz]

Haven’t notice a drop in in MPG’s. The noise isn’t from one particular area. It doesn’t really matter the speed it occurs when I am just press the pedal down enough to maintain my speed. The noise and feeling is very similar to if you were to let off the gas and then press it down again.  My current guess is that one of the spark plugs is starting to go bad and is not firing like it is suppose to. I just hit 105,000 miles on it. 

[Lsgun1]

How long have you had the truck?

[Mileguru]

I have a strange sputtering sound too. It sort of sounds like a paper flapping in the intake tube, but it's also like a helicopter sputter sound. Seems to be coming from the passenger side of the engine. I can hear it in the cab and hear it out the back of the exhaust. No loss of power and it also comes and goes - no rhyme or reason. When mine is making the noise, it will do it mostly at light/medium throttle like you said. I'm taking it into the dealer tomorrow as a matter of fact. But watch it not make the noise while I go on the ride-along. This just started happening about 1000 miles ago (and I'm around 21,400 now)

 

I also have the rumble strip feeling in my steering wheel that I'll have looked at tomorrow. They'll probably do a transmission fluid flush to get the new 8-speed fluid in there. Here's another thread about the rumble strip feeling.

<https://www.gm-trucks.com/forums/topic/237154-2016-silverado-1500-rumble-noise-and-slight-vibration/>

 

My mods are: No V4 because of the tune and the supercharger, methanol injection, smaller ZPE pulley, gates green belt, catch can, AEM dry filter, and Magnaflow 12909. We'll see if they open the hood and say, "Nope, too many mods, not touching it."

Edited April 6, 2020 by Mileguru

[Mileguru]

My sputtering sound issue turned out to be a broken exhaust manifold gasket. Replaced under warranty and it's all good now. Torque is back where it used to be.

 

And the rumble strip feeling has gone away with the new 8 speed fluid. It's only been 200-300 miles, but the clunks are very rare now, it shifts better, and the trans temps are way lower.