I've always had a loud hissing sound come from around my throttle body, is this normal? I have a F.A.S.T ecu with a 790cfm throttle body that's feeding a 350 SB. Do you think its too small? I'm just curious because everbody ask me the same question.
When the IAC has to let alot of air in to idle the engine, it will hiss. If you can check your IAC counts, they should be right in the middle. Look for a procedure in the FAST documentation on setting the base idle speed. You might have to adjust the stop screw.