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mpersell

Tried E30 in 2007 Dodge Ram FFV

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Truck doesn't like E30 very well.  Power is down and consumption goes way up under any kind of load.  Mileage is worse than on E70+ (close to Full tank of E85).

 

I'm wondering if when we are switching between fuels..making significant switches between blends should the vehicles computer manually be reset/reboot ? ..  Like when adding a new program on your home computer you reboot

 

 

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I don't see the same power/performance problem running

 

E30 in my VW Jetta.  Maybe a little increase/decrease in

 

mileage, but better performance climbing hills.

 

 

I wonder if we're missing something in the blending process

 

or an additive that would otherwise be there at a blender pump.

 

All I'm currently doing to get to E30 is a splash blend..

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I got 30.0 mpg on the last tank of E30 in my '06 Impala (flex) on a 30% local and 70% high speed run to Chicago and back. This time of year it will do 29-31 on E10 and and 23.5-24 on 70% ethanol. I was testing some lubricity and detergency additives but thus far have seen no verified effect. E20 so far also gives me very close to the same result as E30.

 

Sounds like Mpersell's ECU did not adapt properly-- have you tried E30 on multiple sequences? What about E20 or E40?

Your truck's ECU may have a similar issue as my Impala once did- miscalculating alcohol blend- a flash fixed this- if I would have had a scan tool with live data at the time i could have caught this sooner but GM did not yet have the flash ready anyway. If you have such a scan tool plug it in and an FFV should have the alcohol % in your live sensor data section (at least my Impala does). Could it also be that the fuel/timing map is incorrect at this level of alcohol?

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Power is down and consumption goes way up under any kind of load.

 

Isn't that the way it is with most Dodge products?  :D

 

Sorry...

 

Anyway, it does sound like some quirk in the ECU programming.  My guess would be that they optimized the program for unleaded and E85, and not really anything in between.

 

Still, try running a couple tanks of E30 through it and see if it doesn't improve.  Trial and error, keep track of your results, and all that.

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I

Sounds like Mpersell's ECU did not adapt properly-- have you tried E30 on multiple sequences?

 

Yeah thats what I was leading too.. wouldnt a "hard boot" of the ECU doa complete refresh  .. remove the battery cable for 15 minutes and drain the ECU's memory ..then test E30 for MPG.. 

 

same for switching between any blends ..for an immediate ECU reset instead of waiting for the ECU to cycle through..how ever many times 

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Dan- depending on how Daimler programmed the ECM, it might simply recalculate the next time he fills up. GM used a 3-4 gallon threshhold for fill to force a recalculation- if the tank sending unit moves up 3-4 gallons then the ECU says "go look at sensor data and recalculate"- or so I was told by some GM folks. This must not be done very quickly because after I fill I may be 5-8 miles down the road before the ECU stated ethanol % gets close to the blend I know i have. Hopefully he will not have to power down the ECU to reset it but this may be the case- mine once ran rich for 8 tanks of E85 and this did not correct until I put it back on E10 for 3 tanks and then back to E85. I then gained 2-2.5 mpg when the ECM recalculated (and chose a new map?).

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. GM used a 3-4 gallon threshhold for fill to force a recalculation- if the tank sending unit moves up 3-4 gallons then the ECU says "go look at sensor data and recalculate"- or so I was told by some GM folks.

 

interesting tidbit Phil..yeah if it works that would be an easy solution ..so either it dosent work as well as is supose to ..or the GM folks were pulling your leg :D

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. GM used a 3-4 gallon threshhold for fill to force a recalculation- if the tank sending unit moves up 3-4 gallons then the ECU says "go look at sensor data and recalculate"- or so I was told by some GM folks.

 

interesting tidbit Phil..yeah if it works that would be an easy solution ..so either it dosent work as well as is supose to ..or the GM folks were pulling your leg :D

 

I am confident of the 3-4 gallon recalc in a GM FFV - at least on the '06 models BUT that does not mean that other years and certainly not other brand FFV's follow this same strategy. Keep in mind also that if they did follow this strategy that if you filled up with NL somewhere and drove a few miles to an E85 pump, then only put in <3-4 gallons- it might not ever correct itself in that tankful and instead just do long term trim adjustments. Some FFV's reportedly lacked fuel maps for 15-60% ethanol at one time because automakers did not know that N.Dakota used E60 in extreme weather and I guess they did not anticipate people mixing fuel when they filled-- if true- this is kind of hard to believe. If an FFV really has all these maps (cells) loaded in the ECU this would explain why it can be tough for aftermarket add-ons or modifications to replicate the cold start and drivability of an FFV. It also may explain some of the mileage loss that FFV's have with conservative automaker's tunes. Does anyone know how many fuel maps or width of cell data range can exist in a FFV ECM?-- unfortunately I got most of my info from the less technical big picture auto folks.

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Unfortunately authoritative details on engine mapping is really hard to get. Most of the info on the Subaru is "derived" from reading Fuji Heavy Industry patents and using them as basis for testing to confirm the strategy was implemented.

 

You can do an ECU reset in a matter of seconds, pull the battery post and then step on the brake peddle to create a current draw to pull the voltage down to zero quickly (there will be some residual charge stored in the electronic components -- capacitors  -- in the ECU and other electronics which take some time to drain off without an overt current draw.

 

That should force the ECU to detect that all the readiness indicators are not set, so it will start from scratch calculating the proper map. That 3-4 gallon re-calculation threshold is an interesting tidbit to keep in mind, and would explain some of those media tests too, if it takes several tanks of fuel to recalculate.

 

On the Subaru it takes about 4 driving cycles for it to internalize adjustments in the long term fuel trims, so a sudden change in fuel on a Subie is handled with short term fuel trims until the engine is shut off and cools down 4 times.

As mentioned the ECU programing changes year to year and model to model and in some cases changes during a model year as updated ECU flashes become available to fix discovered bugs.

 

Larry

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