Idle time

If you can cut that idle % as much as possible you will be flirting with 7's!

 

Just to clear this up... his fuel economy while driving won't go down but his fuel usage will be reduced if he cuts his idleing time.

Mine is about 3%... no APU but I do have an ESPAR bunk heater.

 

good point krooser---but with a large idle time it does really give a false mpg doesnt it?
and other than an apu the espar is the way to go---i have never had an apu,but wouldnt want to be without an espar

 

I have taken apart lots of engines for a problem and when you look at the liners they are a light brown tone to them, and the rings are stuck, there is a cost to idling. When the motor is Idling the combustion preasures are low and the fuel does not burn completely the piston does not expand to the proper size, and everything carbons up. Then you drive it and put it to work and the piston grows to the proper size and leaves polished streaks down the liner.
Their is no positive advantages from idling the engine that is why most come with a 5 minute idle timer. That is plenty of time to warm it up enough to safely drive.

 

But you can't figure your MPG accurately if you figure idle time into the equation... they have to be separate.

If you fill your tanks, run 1,000 miles and never idle you get X for fuel economy.

If you run the same run and idle for 10 hours, your MPG # will fall...

Your ECM never uses idle time to determine fuel economy... it only computes that info when the wheels are turning...

 

ok--losing me a bit---so are you saying the ecm mpg would be accurate as it doesnt take the idle time into consideration?
but a manual computation wouldnt work as it still has the idle fuel in the calculation?

??

 

hmmm i am sure on the detroit ---if you have to idle at night--when you wake up--your mpg is down cause of the idling--then thruout the day it comes back up during the day as your drive time eclipses the idle time

 

ECM mpg is only computed when driving... at least according to a CAT service mgr. I know my 3406 wouldn't have a lifetime of 6.32 if you figured in the first 950,000 miles of ownership (the PO of my truck had a 55% idle time according to the ECM)...

The only accurate way to figure MPG is to shut off the engine and not idle when doing it with a pencil.

 

On a detroit, in the fuel report section you can read overall fuel MPG and driving MPG. Thats where you can see how much idle affects the truck.

Can't speak to how the cat works, don't have the software