heya, try something like
SOUND* snd_tankidle = ".wav"; //enter soundfile name here
var hnd_tankidle; //handle for playing soundfile
function toggle_engine(){
//toggle to the new state
engine_state = 1 - engine_state;
//if engine is now on
if(engine_state){
hnd_tankidle = ent_playloop(panzer, snd_tankidle, 77);
//if engine is now off
}else{
snd_stop(hnd_tankidle);
}
}
//....
void main(){
key_e = toggle_engine;
}
this is untested but will show you the use of sounds and handles
if this keeps switching on and off while you're pressing 'e', it'll be something inside you action, posting that code may help
hope this helps