Odd chuffing sound from engine?

Did this, bought a Bluedriver unit and it comes back after a full scan with no codes.

 

Is your AC / defroster on? Mine does this at idle when any of those are turned on. Completely normal.

 

I'm no help, but when you said chuffing sound I thought steam locomotive.

 

At idle, the truck will occasionally enter a mode that makes it sound like a diesel. As I understand it, the mode is using both direct and intake fuel injection at the time so as to clear out any carbon deposits.

 

I checked they are not.

 

I'm taking about learning and understanding the engine operation by monitoring engine parameters st various conditions.

 

Yes, this is one reason why I bought the Bluedriver, it shows you what's going on while you drive etc.

 

Look at evap purge PIDs

 

What was the culprit?