I think you (other dpf'ers) make up their "saved" carbon footprint in the extra fuel they burn......doesnt it just cancel each other out?

 

Possibly, but I also need to pass inspection and emissions.

 

I really don't mind the DPF myself. This is so much better than the 5.4 pig I used to have. I think throwing the banks on there is the right approach.

 

I don't agree with the masses here on the LOM accuracy.

Both my 6.4L and 6.7L trucks have proven to be reasonably close when comparing the LOM with the hand-calculated fuel economy. Now this can only be done if you reset the LOM when you fill up and then not again until filling up again, as resetting this in the middle of the tank changes the data set the meter is calculating.

But if you reset it and take a drive, the PCM is calculating the fuel it injects to run the engine against how far the vehicle drives. This is not something that's subject to an accuracy variance simply due to the duration of the sample data, as the PCM uses injection pulse data to calculate this, which will remain accurate across a few seconds or a whole tank.

Both PSD trucks were accurate to within +/- 5% of the hand-calculated average. If I were to reset my LOM each trip I would retain that <5% margin of error, but I would have absolutely no way to double check the accuracy against a fuel dispenser.

I do agree with those who say that the mods will not make any meaningful difference in efficiency. The major source of resistance in the exhaust is the DPF, and I think the turbo negates most of any efficiency gains to be had at the air intake.

 

Which is unfortunate, But I understand that.

 

You're talking about a stock/untuned truck, correct?

As I previously stated, the LOM looses accuracy if it's constantly reset (on a stock truck)...and tuned trucks; Spartan, IDP, etc. dramatically throw the LOM off; regardless of whether or not it's constantly reset, that's a fact...

 

Correct, I've never run a tuner. I think I got you beat, I'm lazy, a nerd, and a CHICKEN!!!

But seriously, I've seen lots of examples of how crazy the LOM gets with tunes.

 

Exactly Tom...my buddy with his Spartanized F350 lost his mind with LOM readings in the mid to high 20s (as high as 28?!) when he first got tuned, until I had to school him about hand calculating...kind of took the wind out of his sails to say the least!

 

I watch my mileage pretty closely last tank was 332.1 miles - split 50 / 50 town & interstate - 23.7 gallons for 14.01 mpg "lom" read 15.2 mpg this tank saw hyway miles at 68- 72 mph -

 

I remember that day!!! I thought I found the holy grail when I was getting 24 mpg on the lom...unfortunately that wasn't the case and I was extremely disappointed

 

Why would the LOM loose accuracy if it is constantly reset?.......

 

I believe Ronin was referring to the variance between the LOM and the MPGs for the tank.

I've always found the LOM to be nearly dead on in every circumstance. If you want your MPGs for a single trip and reset it before the trip it will be accurate, but there will be absolutely no way to verify unless you fill up every trip.

 

the LOM is recalculated every 15 seconds. if your last few miles are uphill, heavy load, etc.. then the mileage will fall. if crusing at slower speeds it will rise.

over really long distances of consistent driving it can get pretty accurate.

we call it the LOM cause for most of us, it is NOT accurate enough, and can be wildly off.

as an example.. when I do not tow, my mileage is good at 12.5 solid as a rock.
when I tow, the best I will get is 8.9 (over 900 miles all highway, stop only for fuel at 70+mph)..

so, when I have the display at 12.5, and I hook up my trailer.. what is the MPG? not 12.5 thats for sure.. but the LOM says so. 100 miles from here it will be 11.1.. is that accurate? no.. the miles til empty is working off the last calculated MPG.. that that is wrong too..

so, net.. use it as an 'estimate', adjusted after the fact for what you are actually doing..

Sam

 

Hi Sam,

I disagree with this. The LOM is an average calculated over the time elapsed since it was last reset. If you reset it and drive a tank empty and see 12.5, that's the computer's best guess as to what you got for that tank. If you don't reset it and hook up your trailer, you STILL got 12.5 for the time period the truck was calculating it.

The numbers are reasonably accurate for the time period used for the average. If you hook up your trailer and drive for another tank and see 11.1, that means your truck should have gotten 11.1 over the course of the previous unloaded tank and the one towing. Meaning if you add the mileages together and divide by the sum of the gallons used you should see somewhere around 11.1.

 

You must have the 1 LOM that actually works then, every one of them I use over states mileage by 1-3mpg. I left the mileage alone in my Mustang for 12K miles and it was consistently 1-1.5 over. The dealer reset it and it has taken a few hundred miles but is back to its normal 23.6 area.

The LOM in the '08 F250 is a bit harder to track down how far it is off it has been closer to 3mpg over a few times but with multiple drivers who like to reset it it is harder to get a lot of accurate info.

If anyone gets 25-30 they'd be refiling every 700-900 miles I doubt that is happening. I can make the 6.4L read up there above 30mpg if I reset it at the right times, going down hill with a tailwind for example. In reality it gets 11-16 on the LOM which is usually 2 over actual mileage.