When my truck shifts from 1st to 2nd at full throttle I hear a sputtering sound coming from the exhaust. Some times its not very loud other times its louder. What causes this?

 

I have the same sputter sound I don't know what it is but I didn't hear it untill I install the boost bypass kit.

 

What you are hearing is the torque reduction kicking in when the truck shifts at full throttle, the computer is programed to drop four cylinders (I think) for a few miliseconds as the truck shifts, ford did this to take some of the stress off the transmission as it shifts at wide open throttle.

I hope this helps a little.

Larry.

 

What Larry said....................Some vulger individuals refer to it as a 'fart'. I'm glad the more mature of us don't do that .

Dan

 

Take that sputter and run it through a Bassani and it turns into a symphony WABBA-BAP or something...

 

Could it be louder when the back window is open?

 

Mine has it too... I am bone stock though....
I figured it was the PCM dropping cylinders but the funny thing is, it doesn't do it all the time.

 

Thats exactly what it is and does it all the time but sometimes you dont hear it