I cant find an answer to this anywhere in search, so will ask it here. I do not have any engine sound of any kind for the shelby gt 350 or both AC Cobras. All I hear is something that sounds like a gear linkage or clutch, other wise-dead silence. There is also another car with no engine sound, but I cant remember which one it is. All the other cars, that I have tried so far, have good engine sound. What can I do to fix it?

Thanks in advance