High then Low idle hissing????

[powerstroker01]

When you first start the truck (when its cold) the motor wil go high then low like a surge or something. When it warms up about 20min or so it goes away and you wont hear it again untill another cold start.

This is not my truck its a friends truck 2002 7.3 f250

[Blue01F250]

thats because its trying to warm itself up... completely normal. and there is no need to let it idle 20 min to warm up...

[redstroker_2002]

and there is no need to let it idle 20 min to warm up...[/QUOTE]

whats wrong letting it idle. when its cold i dont shut it when its cold and its snowing i cant afford to shut it off if it wont start again i lost a few hours of work so its cheaper to let it run. i just idle up and its fine. doesnt use alot of diesel. when it was -15 degrees one night and it was idle up for 8 hours and it used 3 gallons but it was nice and toasty and the other snow pushers where trying to thaw there trucks out lol.. haha

[silverF250]

I think he is saying that it will warm up faster once you start driving it. It should only take about 5 mins for it to warm up in cold temps before you go anywhere. I doubt he is against warming up altogether just it doesn't need that long a time to be able to drive.

[Blue01F250]

The hissing sound is your EBPV closing off and the exhaust gasses hissing by it...


and definately - i said there is no "need" to let it idle 20 min to drive somewhere -- but it will stop hissing and the high idle once its warmed up or you touch the break to shift or if you're driving and go WOT.