i have a question i was wondering if the throttle body is supposed to be open when the car is not on, cause mine is open like 1/5 when the motor is off, i was wondering if its supposed to be like that? thanks

 

Be very careful when starting the truck -- especially in cold weather! It's designed to be open ~1/5 based on 80* weather. Since colder air is more dense you could get a "supercharger" effect for a split second. It'll cause your IDLE RPM to go off the chart, and this has shown to shorten ROD life in some cases. The only solution is a custom tune, y0!

Okay, sorry... I had to get that out of the way. I know many others have thought this to be a silly, if not troll, thread too. My first real question is why would you be looking at your throttle body anyways? I'm not sure about a 4.6, but they're not exactly easy to get to on a 5.4L...

Idle... if the TB was 100% closed the truck wouldn't idle. I haven't studied the TB's on newer F150's, but on my '88 Mustang it would hit a set-screw used to change idle RPM (along with using a VOM on the TPS).

 

Yeah, what he said!

 

because i was changing my intake and notice that the tb was open pretty big

 

that should be equal to about 15%. which to me would be right. it should be open a bit when cold to be able to start up. all that i have dealt with have been open a tiny bit to allow air to come in when at idle.