Ihave an '06 5.9
I dont know how long to let it idle before i shut it off?

 

I do mine for at least 2-4 min. depending on my trip. If I'm pulling a heavy load on hot day then longer but its its just to walmart then prob 1-2 min.

 

From the service manual:

TURBOCHARGER “COOL DOWN� CHART


Driving Condition[/b]
Load[/b]
Turbocharger Temperature[/b]
Idle Time (in minutes) Before Shut Down[/b]

Stop & Go
Empty
Cool
Less than 1

Stop & Go
Medium
Warm
1

Highway Speeds
Medium
Warm
2

City Traffic
Max. GCWR
Warm
3

Highway Speeds
Max. GCWR
Warm
4

Uphill Grade
Max. GCWR
Hot
5

 

if Im pullin off the freeway and have several traffic lights, the turbo should cool off pretty well while sittin still...if I zip into a locatio right of the highway or freeway, then i let it rest for a couple minutes to cool down. was told that the 1st gens with the undersized turbos dont really require cool down time but i do it anyway..that way Im ready to own a new one!!!

 

I usually cosat 5 blocks in my subdivision with rpms at 7-8 hundred. then I sit for another 30 seconds or so after driving home from work.

 

I let the the turbo timer on the Edge do it, I set it at 300 (pre-turbo) and it shuts off when it hits the 300.
When towing I let it run while I'm getting fuel and it shuts down long before I'm done.