2008 6.4 Diesel Regen MPG Yikes!
 

I know the regen cycle wastes fuel, but never really knew how much, until yesterday. The truck went into regen on the highway and remained in regen for 25 miles. During that time it displayed I was getting 10 mpg.:-arrgh
After it cleared, traveling at 60mph, I was getting 19 mpg.
When removing the exhaust system to get rid of the particulate filter, is there a program for the computer to delete the regen cycle?

Yes, you have to program the truck. Delete pipe (in place of DPF) and programmer to fix the regen issue.

Don't do one without the other.

smog?
 

If your state smog tests diesels are you SOL (can't do the delete)?

but really you were getting like 7 and 14:-X19

I've determined each full regen cycle burns about 1-2 gallons of fuel. Most is burned in city traffic since there's not much engine heat otherwise available to help keep things heated.

No doubt about it, regen burns fuel. But probably not quite as much as you think. The vast majority of folks that tune only to delete the DPF report minimal fuel economy gains if any whatsoever. Some have even reported no significant difference. This is with a stock tune that removes the regen function.

Real efficiency gains are to be had with the high horsepower tunes, but that comes at the risk of possible expensive problems caused by the increased power.

Regen on the 6.4 burns quite a bit of fuel.

The only reason I think we see people getting the same mileage with a stock - DPF tune is that they're driving harder with the thought in the back of their head that they got an efficient machine.

That is my theory, and I'm sticking to it. Stock without the regen will yield better mileage if driven identically.
That being said, most "stock -DPF" tunes I know of still use EGR, which also kills mileage off and can cause crappy combustion.

I've seen the testimony of more than a few that contradict this. Can you demonstrate otherwise?

1-2 gallons per regen equates to 5% of my fuel consumption (!!) I've read studies showing the amount of EGR used iin our 6.4 (a lot more than the 6.7) incurs about at least 5% penalty by design.

I think these numbers are in the ballpark since most guys who hand calculate before and after deleting the DPF and EGR get about a 5-10% increase in mpg's--meaning about 0.5 to 2mpgs increase if driving habits don't change.. Another way to check is to look at Distance-to-Empty just before a regen starts and compare it to immediately after regen completes plus the distance traveled while in regen. I lose about 15-25miles per regen == 1-2 gallons

It appears the low-end gains apply to city traffic, but the ones who see the most gains are when towing and lots of freeway driving, or, in other words, at high loads. Certainly, anyone who thinks they can get 20mpgs while towing will be in for a huge disappointment!

I no what you mean my cadlic convertor stoped up on me an I took it off an it smoks in the city

Regen EASILY uses one to two gallons per episode, one you have all the wasted fuel pumped into the chambers to clean the DPF, two> it always starts just as you get ready to get off the freeway to go home or to work, so you stay on the freeway to finish your regen. So you not only loose fuel used in the actual regen and the absolute waste of fuel driving through the regen. :)
The best I ever got undeleted was around 17.5, I have yet to drive a non stop freeway tank of gas deleted but have had many 1/2 tank freeway 1/2 tank city and have gotten between 18 and 19. I'd be willing to take a safe bet that a full tank of fuel burnt on the freeway would get me between 21 and 23 easy. I am older, in my fifties so I don't abuse the skinny pedal a lot but when you push that sucker down it sure gets the hell out of it's own way real nice.

It took me a second to digest this, and when it hit me I had to smile that you are right. The actual REGEN does not consume a gallon or two but Ford tells us to drive "out" the REGEN so therefore the extra 15 minutes, or 15 miles is another gallon or so of fuel. Driving around, just to complete the REGEN, plus the volume of fuel injected into the rear cylinders to increase the temps. Good Point, the pure waste of fuel just to complete the process is not productive mileage.

I generally don't do an extra driving around. I know about when my regens are going to happen so I plan for it.

If I am wrong I just interupt it and let it idle long enough bring the EGT's down and shut it down.

Then I know upon start up it will want to finish so I plan on it.

Mine made oil all the time so I made a point to drive thru all regens, didn't help, so as the say, Hasta La Vista Baby!

My hand calcs also indicate that the regen cycle consumes approx. 1-2 gals of extra fuel, in other words fuel that I wouldn't have used to go the same distance in the absence of a regen. I'm a whole lot less efficient at capturing the start of the regens since I got the PCM flash that does not keep the display "Cleaning Exhaust Filter ", though I plan to rectify that inaccuracy with my new Insight CTS which will display when I am in regen.

The hand calcs of my extra fuel consumption during regen are loosely corroborated by the Lie-O-Meter as it is affectionately known around here.