Tweaking for best Fuel Economy??

[soutthpaw]

Ok I am back at it, before I drive back to Colorado from CA I want to see if I can make an even more fuel efficient map...
I am really looking to tweak my fuel usage while crusing on the freeway..
that is right at 2000 RPM and 75mph.. less than 30-35% throttle and usually 2-5lbs of boost pressure...

from comparing the stock and 75FS fuel sipper tune from Bill as well as the 80hp tow I am looking at the following
SOI is already pretty advanced compared to stock so I don't think i will make any changes to that and I aready adjusted the high altitude SOI on all of my tunes.
Injector pulewidth is the same across all the tunes so being that I am using stock injectors I am planning on leaving those alone too
I notice a little earlier and steeper curve in the ICP Duty cycle which may be adding a bit more fuel each stroke but may also just get better atomization of the fuel.... Maybe I will bring this closer to stock???
OK so the image below shows the following settings with Black being stock, Blue being Fuel Sipper and Red being 80HP
from left to right are MASS FUEL DESIRED: LOW BOOST FUEL: ICP DESIRED: AND FUEL PULSEWIDTH MULTIPLIER.. all around the RPM and Throttle position range I am in at freeway crusing speeds

I am thinking of lowering the Low boost fuel and/or the Injector Pulsewidth Multiplier to stock or slightly below stock for these ranges to gain fuel economy.. Any ideas or thoughts on this

[cleatus12r]

Originally Posted by soutthpaw

I am thinking of lowering the Low boost fuel and/or the Injector Pulsewidth Multiplier to stock or slightly below stock for these ranges to gain fuel economy.. Any ideas or thoughts on this

So you'll end up with a slightly more aggressive desired ICP, earlier SOI, and a really doggy truck.

The problem with doing that is......

The PW Multiplier map is where the extra fuel comes from. Without the longer fuel injection event and the low boost fueling set at stock.....you'll be right at stock power levels. I can't say (since I haven't done any dyno testing with this particular setup) whether or not you'll actually have less power in setting the PW Multiplier to stock and leaving the SOI and SOI Delay the same as it is in the higher HP settings because you're injecting less fuel earlier; there will be a point where the fuel isn't burning anymore since it's no longer being injected at the optimal point ATDC to push down on the pistons.

You can try it though....nobody is stopping you!

[soutthpaw]

but it would only be Doggy in that light throttle/2000rpm range... Maybe I just need to run 1 tank on the stock setting there is about as much chance of that happening as there is of me being able to keep the cruise at 65mph which would probably net a nice MPG increase...

I don't even have the stock tune loaded. I did previously and don't think i ever ran it for more than about a minute before i had to go back to the 100 or even the FS tune. If i could get the throttle response to be a little better in stock I might be able to put up with it for a tankful... Don't know how I even lived with my 2 previous trucks that had the 7.3 stocker in them.. I am just gonna hate driving my 4700 International once I get it done. So will definitely have to pull the PCM and ship it to Bill so he can see what he can do with it...

So based on what u said in your reply, maybe I should start by dropping the PW Multiplier values down about 10% or so under about ICP of 13.
Is the low boost fuel just a maximum limit setting for said parameters or does it actually command that amount of fuel? If its just a limit then I can see it would probably not affect cruising MPG..

[cleatus12r]

Originally Posted by soutthpaw

but it would only be Doggy in that light throttle/2000rpm range... Maybe I just need to run 1 tank on the stock setting there is about as much chance of that happening as there is of me being able to keep the cruise at 65mph which would probably net a nice MPG increase... It's really disheartening concerning the mileage increase when slowing down. If I drive 75, then I can get 16-17 MPG. But since I mostly drive 65-68 MPH, I can usually do 19.5-21 depending on whether I drive east or west (slight upslope driving west).

I don't even have the stock tune loaded. I did previously and don't think i ever ran it for more than about a minute before i had to go back to the 100 or even the FS tune. If i could get the throttle response to be a little better in stock I might be able to put up with it for a tankful... You can...the Mass Fuel Desired map along with the LBF map will make "stock" run pretty well. Also increasing the desired ICP 100-200 PSI in those certain operating conditions helps too. I don't think I'd run too much extra, but a little would be better. Don't know how I even lived with my 2 previous trucks that had the 7.3 stocker in them..It's weird because I have all of this stuff.....but I run "chipless" most of the time. It seems backwards but the factory did a pretty good job. I am just gonna hate driving my 4700 International once I get it done. So will definitely have to pull the PCM and ship it to Bill so he can see what he can do with it...

So based on what u said in your reply, maybe I should start by dropping the PW Multiplier values down about 10% or so under about ICP of 13.
Is the low boost fuel just a maximum limit setting for said parameters or does it actually command that amount of fuel? If its just a limit then I can see it would probably not affect cruising MPG..I'm no expert and I could be bass-ackwards. I'd call Bill next week and ask him. I am probably way off base. I would ASSUME that the LBF table works in conjunction with the Fuel limit vs. RPM map. I believe it's a percentage.....and yes, you can run 100+ in those tables. However, I don't recommend it because it can make the truck a little TOO responsive.

Here you go.

Your best bet is to talk to Bill.

[soutthpaw]

I made a couple of tunes and tried them but just didn't cut it... I like the get up and go too muchso i went with the 60, 80 and 100... dropped the FS as it really does not seem to make much difference... looking at the Fueling maps it looks like the 60hp would be pretty economical as it really doesn't add much fuel compared to the 80 and up... Im gonna try these for a while and see....

[soutthpaw]

Well I have been limiting myself to driving 65 or slower this tank of fuel and it looks like I am in for an increase in MPG. I have been running the 100HP tune... maybe I need to merge the shift maps from the FS with the 100hp tune for more mpg.

Might try tweaking the ICP up a bit and the pulse width down a tad too..

Oh does anyone know how Ford's Lie-O-Meter actually caluclates the MPG estimates (which values it uses etc)

[cleatus12r]

Originally Posted by soutthpaw

Oh does anyone know how Ford's Lie-O-Meter actually caluclates the MPG estimates (which values it uses etc)

Here's the technical part:


fuel level sensor data
Data Output Line (DOL) fuel flow data from the PCM
vehicle speed signal