Under acceleration sometimes my car sputters for a second, I hear a rattle and then it kicks back in. Is that knock or knocking?

 

Engine "knock" (or auto-ignition) is when the air/fuel mixture inside the combustion chamber combusts before the spark plug is supposed to fire.
The 'pinging' noise you hear is the explosion of the fuel mixture being compressed by the piston when the cylinder is still traveling to top-dead center on the compression stroke.

If you're getting a rattle that's similar to what I described above, it could be auto-ignition issues.
However, a rattle (metallic in nature) sounds more like a possible timing chain issue.

First, are you using the proper grade of premium fuel in your turbocharged S-model?
Have you ever had issues in the past with sputtering or hesitation?

- Erik

 

I don't know why the call it ping. If the sound is like a tin can with a few stones in it rattling then its knock, ping, pre-ignition.

If there is hesitation then its timing. Maybe bad fuel. Maybe vacuum leak. Maybe something else.

First dose with some kind of cleaner. then go out and do 5 or 10 WOT runs to hopefully burn out what is in there. Extra carbon can cause pre-ignition.
They call it an Italian tune up.

If anything weird or scary happens go to the service mother and have it looked at.

Cheers.

 

No real sputtering or hesitation issues in the past~ just this and this has happened a few times recently. And I use premium gas.

 

What kind of cleaner?