I took a brand new Cummins 600 on a test drive today.

It had 14 miles on it and the overhead mileage display never got past 8.7 miles per gallon.

The sales guy said it hadn't been calibrated yet, because it was so new.

I've never seen, on this board anyway, that these things need to be calibrated.

Is this true?

Anyone know?

Thanks.

DT.

 

I don't know about being calibrated but I think I know why the MPG was low;

1. Brand new motor, it needs to loosen up a bit
2. Everybody who has been test driving it has been full throttle everywhere to feel the power (this includes the kids that work on the lot and the testers at Dodge)
3. The engine has seen a lot of idle time being moved around on the transport trucks and trains, this will kill your overhead MPG.

Take one out for a test drive and get it on the open road and press the reset button, it will show better.

 

Calibrated? That's a good one!

I agree with royalnine about the low readings on the computer. Long term, the computer is only good for a best guess at your mileage. Add some aftermarket injectors or fueling box, then forget it.

All I use mine for is to tell me what the outside temp is plus or minus 5 degrees, and give me a general indication of where the nose of the truck is pointed direction wise.

Matt

 

I wonder if he was confused, the owners manual on my 2003 speaks about calibrating the COMPASS. If the MPH/KPH speedo is correct how could anything else require calibration? PM Luke S, he would know. He's a dealer in Herman, MO....Nat

 

when I first picked up my truck it showed something like 8-9 mpg. I pushed the reset buttom and the milage jumped. the truck has spent a bunch of time idling and not much time moving. I would say that is normal.....

 

Dejavu!
Yeah mine too. I reset it at every fill up and compare it to the calculator. It's usually 1mpg shy so I'm getting better than the overhead says. I reset it when I hook up the 5th wheel too. The dang thing is addictive. I leave it on compass and temp so I don't get a cramp in my foot trying to keep it reading over 18mpg.

 

I have personally reset the computer on a 600 (2WD DRW)and a 555 (2WD SRW)both new and 600 said 11 mpg and 555 said 17 mpg....same road same driving style....there is a huge difference..... and a dually don't knock off 6mpg...at least there is a difference in early built 600's (Dec.,Jan.,Feb.)

 

Just got back from the cabin and I got 17.1 with my truck. It's got 8000 mi on it and most of it was towing the 27' car hauler. We call that "breakin in" I go up and over the pass going both ways so it's not just running down the flats. AND I've got 4:10s

It didn't start out that way.....

 

Another salesman speaking from his bum

 

Did a road trip late last week, empty with A/C on avrage 74 mph in 85+ heat and got 17.77 mpg

 

I do the same thing , I have to leave it on compass, or I'll drive myself nuts trying to stay in the "mileage zone"


Glad to hear it's not just me

Dennis

 

I disagree. While your experience may be different (or my mileage computer is the exception), I have compared hand calculation of fuel mileage vs the computer readout and found the L/100KM (i.e. MPG) to be out by .1 L/100KM, which is insignificant.

The method I used was to take the 15 minutes at the pump to fill the diesel right to the fill lip. I then drove the truck until almost empty 650+ kilometers, then refilled it using the above method (to the fill lip).

Not sure what to say, other than based on my experience, the computer is capable of returning a very accurate fuel mileage calculation. Maybe yours doesn't work correctly.

 

Guilty!

 

Calibration of the fuel mileage display is accomplished per the instructions below:

1. Run the truck completely out of fuel.
2. Purge the fuel filter.
3. Remove, clean and replace the spark plugs.
4. Clean and lube the exhaust bearings.
5. Fill the tank with fuel.
6. Drive at 47 mph until the tank is empty again.

What do you think?

 

Somehow (unfortunately) it would not suprise me... But, be careful, there will be 20 posts here tomorrow saying "I followed your directions, and it didn't work?"

Just kidding, have a good day