when i start my 7.3idi it idles normal, if i tap the gas or give it gas the idle jumps up to about 800rpm. it only does it when it's below 80. if it's over 90 degrees outside it doesn't do it. or if the truck's warmed up it doesn't do it. i've heard of turning the key on, tapping the gas then starting it to initiate fast idle. should it do it even after its already running? also, in the morning should i start the truck, let it build oil pressure then tap the gas to initiate fast idle or should i do it right off the bat? should i let it sit for 5 minutes or so and idle down before i drive it or can i just take off? obviously when it gets cold here in a month or 2 i'll let it warm up but right now it's anywhere from 50 to 70 in the morning (thats kansas for you).
i'm just curious because it doesn't seem to have as much power while it's idling fast. it tends to fall on it's face and the mechanics is alot louder. i can tell when the fast idle shuts off. if i happen to be cruising for example at 35 when the fast idle shuts off.the engine will get quieter or smooth out. if that makes any sense. if i'm at a stoplight the idle returns to normal.

 

Yeah, it's supposed to work like that....I'm not sure about it seeming like it has less power though.

 

so what do you do, do you let it warm up and go to a normal idle or do you just drive it? when you start the truck do you let it build oil pressure before you initiate fast idle or do you initiate it right away? it seems to me that as thick as diesel oil is it takes a bit longer for it to build pressure and one wouldn't want to rev the engine untill it has a chance to.

 

always set the throttle first then start the engine

 

You should turn the key to the on position then set the throttle (push it about half way down) This sets the high idle and advances the timing.

Usually these engines run better with the timing advanced but when cold it's advanced to far to run that way all the time. It's set up that way to help keep a cold engine running smoother with less smoke.