This may be off base, but here are some calculations:

Table below is from the PC/ED manual (misfire monitor):
Entry Conditions:
Entry condition.................Minimum.........Maximum
Fuel desired......................None............35 mg/stroke
Engine Oil Temperature.......50 oC............110 oC
Engine Speed (Low Idle)......600 rpm.........750 rpm
Vehicle Speed....................0 MPH...........1 MPH
Intake Air Temperature........-15 oC...........100 oC
Exhaust Backpressure Gauge...None...........50 kPaG
Injection Control Pressure Duty Cycle....0....50%
PTO off............................None..............N one

This seems to be between 120 degrees oil temp and full oil temp. It is at the initial low idle, not considering any "high idle mod".

Use 35 mg diesel fuel desired per stroke.
Assumption - 1 stroke = 1 revolution
Assumption - diesel density is 0.9 gm/cm3

(35mg x 750 rpm x 60 min/hr) / (1000mg/g x 0.9g/cm3) = 1750 cm3 of diesel used per hour

This is 0.46 gallons of fuel / hr

Maybe some wrong assumptions - hopefully someone will let me know if they are!

As I said earlier, the latest flashes will elevate the idle periodically (I need to re-read the TSB's to recall when and how much)

Here is an example of the thread that I recall seeing for the 6.0L:
http://powerstrokenation.com/forums/...t=18557&page=2

 

After the truck starts, the engine idles for about a minute or so then it automatically goes into a higher idle, is this high enough rpm for extended idle time?
I never looked at the tach to see just how much it's raised.

 

I don't believe so. My recollection is that the typical strategy will raise it to 850...... but I need to check that out in the TSB.

 

The high idle kick in after 2 minutes varies rpm wise depending on outside temp. Example my truck goes to about 1,040 rpm when its around 30 or colder, but if its around 40 deg. it will high idle around 850 rpm.

 

Good info!

I believe the TSB I saw stated that the point that the elevated idle kicked in was actually dependant on either oil or coolant temp (not ambient temp) - IIRC it is oil temp.

 

I should have been more specific with the temps. I take my temp readings from a Edge insight, EOT/ECT when I turn the ignition on in the morning.

 

FYI, the OEM high idle kicks off at 150F-ish.

 

20-30 min is too long. That is wasteful. I feel that with "warm up" in mind. 10-15 min is the max. After that is is unneeded. I let mine warm up for atou 10 min and I use a block heater for 3 hours in the morning.

 

I use the block heater(3.5 hrs on a timer) and let it idle for around 10-15min in the morning. This morning it was -5 degrees F out. Block heater got it to about 80 degrees. High idle mod for 12 min got it to about 150 deg F.

FYI my Bully Dog Monitor has the option for monitoring fuel in gal/hr. Low engine idle is around .5-.65 gph and high idle is 1-1.25 gph. When the engine first fires and is "cold" it will use about twice that for the first minute or so, then level off to the values I posted. I don't know how accurate the reading is though.

 

This is a job for the MythBusters.

 

The 6.0 is a 4 stroke, therefor it does not use fuel for every stroke ??????

 

Ditto that. You can idle it more, but then you might want to clean your EGR every week. Especially when it's actually cold. Let it idle for a few minutes until it goes to high idle. Then flip on your high idle mod.

 

Unless it is ridiculously cold, what's the point of idling for more than a minute or two and then driving easy until it's up to operating temp?

 

Ditto. Why not a dynamic warm up?

 

To much don't do it anymore