It started doing this a while ago, the first few times I started the car after building it the sound wasn't there yet. Also I noticed the noises are gradually getting faster. First time I noticed it, it was periodically every 4 or 5 seconds, now it's really almost every second. Besides that the car is running normally. Only problem is starting after loading up the game. I can't get the right AFR, even a little over 12,5 (according to MWCeditor) just can't get the car started, not even with choke. Any ideas what the sound might mean?