Different sound of engine - D4F 16V

[sasio]

Hi.
I've got a problem with my engine in my Twini.
Well, sound from engine is a problem.
When I push a pedal of gas I hear "tsst" sound from engine.
This sound looks that turbo, and is only 1 second sound.
Every push a pedal = this same sounds.

I try solve this problem but without result.
I removed a cover of AirFilter, remove Filter and insert hand "in engine", and when my friend push pedal I feel a hit of air, not suck air but push air (inversely than normal)
My friends (about 10 person) also have this same problems with own 16V

[Broadcasttechniker]

The moment the trottle opens there is a fizzing sound just as you described it.
But it should be shorter than a second. It is definitively longer and louder than with a mechanical throttle because the opening speed is limited by hardware and by software.
The other observation you made isn't that easy to interpret, but i know that it is difficult to determine the direction of airflow when it is not very strong. For example i can't determine the direction of the airflow of a fan. I can feel it, but i can't tell the direction. I help myself and take a piece of paper looking for the deflection.

[sasio]

Hi.
Today I remove a lot of things in engine, and show the throttle...



Well, the throttle was very dirty, in old oil, and after the clean, I check a crankshaft breather pipe, but is in good healthy...
I cleaned all of dirty things, seal all of parts.... but this sound is still there... not louder, not quitly, this same tsst.
I talked about this problem with a lot of person which have got a D4F in Clio and Twingo, and also hear this same sound, but not everyone...
Some idea?