hi all,
can anyone take at look at my dfco settings..
I would like it to come on easier & quicker. Im not sure i understand some of the settings, specifically the timing ones.
I would like the truck to maintain speed a little more than nose over & slow down during dfco. thats timimg right?
stock 6.0 in a earlier van. looking to maximize milage. Thanks for the help.
1995 van 6.0 maf cal 002 done.hpt
hwy - town 002.hpl
I tried several different DFCO settings and saw no gain in MPG. It showed a slight gain by disabling it FYI.
Holy crap I never even thought to try that
In DFCO duty cycle still shows active injectors but... if I zero out the VE table in the decel regions and DISABLE DFCO I wonder if it will drop to zero!!!
oh my im excited
DFCO is not meant to improve fuel economy.
Nevertheless, shutting off injectors will stop ALL fuel from entering the engine thereby improving fuel economy and allowing engine braking.
Secondly, Automatic transmission using OEM Programming for GM ecu does not engine brake much, or seem to anyways.
So why would there be a DFCO for something that never happens? I set mine to lockup on decel giving engine braking but that is a custom setting.
Finally,
If I Can't an injector cut to happen using HPtuners I would like to design a microcontroller circuit to do it for me, kill injector relay power during decel isn't so difficult. Just finding the correct window trigger is all it takes.
One way or the other those injectors going to turn off when I say...
Excess engine braking decreases fuel economy. DFCO exists to meet emissions.
Engine braking recovers energy from the drivetrain, but the vehicle slows down faster
lets count the 4-stroke cycle and see,
1. Compression, excess energy is lost while engine is running. Compressing low density air volume is easier. So this is +1 for braking
2. Power, friction of rings is similar for braking vs combustion but the combustion event creates blow-by and heat byproduct which is lost. +1 for braking
3. Exhaust, higher vacuum during engine braking is less gas density for exhaust event. +1 braking
4. Intake, higher vacuum during engine braking is more friction for piston-ring, but less intake air mass is less resistance to flow. I would say break even or negligible difference.
Drivetrain wise, the energy accumulated based on mass of rotating parts is as mechanically efficient going up as it is going down the same rate, but engine braking is a minimum rate of change during deceleration, meaning the efficiency of energy recovered is as good as it gets during engine braking.
Engine wise, having the engine run to avoid engine braking is using fuel, whereas engine braking requires no fuel. When fuel is used the engine wastes energy due to heat byproduct, whereas no heat byproduct is wasted from cylinder combustion during engine braking.
Yeah going to have to disagree with you there. Unless you have some kind of data to back up your claim.
I was the D&E calibrator responsible for producing the reduced negative crank torque decel cals for the 2.4 Tigershark in a 5000lb Jeep to save the fuel economy team from failing EPA CAFE requirements. That work?Originally Posted by kingtal0n
Not really data, sorry. I appreciate your response though, Even if you have data, I would be critical. That is a point of science & math I think.
For example there is research out there involving cancer, cell cycles, bacteria, viruses, and engineer'd scaffolds including decellularization that I've found much of it to be incorrectly applied scientific method and unfortunately people that call themselves engineers or biologists that don't have the necessary aptitude to really do their jobs well. There are so many examples of poorly implemented code and mechanical devices I don't think you need evidence of that. Devices improve over time as combined efforts and historical data but the people that work on those jobs come and go with varying level of technical ability and math skill.
I am Not impressed by degrees, papers, jobs, titles, or statistics. However I will peer review any data you have and judge for myself. Even math has a limitation where you miss a single variable and... The only real way to determine where the energy went is to account for it somehow. A Caloric 'bomb' meter for example, very precise measurement of energy released can be performed. It is conclusive evidence of where energy went.
If you wish to write a partial differential showing mathematically, energetically where you think energy is lost I would review that. Alternatively a matlab project could suffice or fill some gap. But the time required to do these things by oneself is... well I wouldn't blame you for not wanting to. I'm not asking you to. I am only saying if you did have something mathematical I would look at it critically. Otherwise your word is no better than mine. And by inspection... it is clear....
In this issue this much is known:
It is clear to me that energy from the drivetrain is used to keep the engine turning during engine braking and this is recovering energy from the momentum and kinetic energy of the vehicle. To say anything other than "recover energy that was originally contained within fuel" would just be ridiculous. And unless there is something wrong with the drivetrain like a backlash issue with the trailing edge of a differential gear or whatever I don't see how parasitic energetic consumption coefficients of recovering rotating energy could possibly equal or overcome the energy lost due to combustion, compression, pumping losses, etc... Its just crazy to me anybody could say otherwise.
A typical vehicle loses all of it's momentum and kinetic energy when the actual brakes are used, so recovering at least some of it before the person stops using regular brakes is ALWAYS Beneficial. 100% of the time.
Last edited by kingtal0n; 06-13-2022 at 04:03 PM.
Always humorous lol. So where does this recovered energy get stored? Unless it's a hybrid with regenerative braking...negative crank torque on decel will cost you fuel. It has nothing to do with the fuel injected during decel...it's the cost of the fuel to re-accelerate after the decel event. Anything that works against you getting to your destination makes fuel economy suffer. None of your walls of text will change that > <
The engine is decelerating whether you engine brake or not. Its a decision whether to input fuel or not. If we choose not to input fuel, then no fuel goes in and the engine dies. Unless its connected to the drivetrain in which case the drivetrain keeps the engine running with no fuel going inside. Is that where you are stuck ?
If you stop making fun of somebody just because they can type and read much faster than normal humans
and start writing math equations or review some data,
this would be much easier
Lets start with this. I am not saying google is always right but, do you disagree with this or not
Take your vehicle for a drive and shut the fuel pump off at speed. Press the pedal to WOT and then let off. Repeat that a few times until you understand engine braking lol. If you run out of gas you want to coast right? Excess engine braking means your ass is stuck on the road and causing a traffic jam in front of me instead of coasting into a parking lot. Don't be that guy.
Engine braking pro articles
https://www.matfoundrygroup.com/blog...u-should-do-it
https://www.youtube.com/watch?v=_bZlb62VVlw
https://carfromjapan.com/article/car...-transmission/
https://www.greencarcongress.com/201...19-ronkko.html
etc... there are hundreds
I can't seem to find a single one that says otherwise. Maybe you can supply some data? Several of these articles and videos show data that indeed- engine braking is beneficial to economy. I'm just asking for a mathematical equation I guess
This example you propose isn't typical. Nobody is shutting off their fuel pump and coasting long distances. This is absolutely ridiculous that you think anybody does this. Have you actually driven in a typical street? People drive full speed up to the light and slam on their brakes. What happens when we use our brakes?
You seem to be confusing kinetic energy of the vehicle with rotating angular momentum requirement to keep the engine spinning (with a fuel pump that is currently running).
Conservation of energy by inspection tells us that under typical situations we need the engine to remain rotating. There must be some source of energy input to keep it running.
Your example of somebody running out of fuel is ridiculous because of course you won't want to slow the vehicle down to conserve fuel in that specific situation.
That is a pro tip for you so you can experiment lol. Specifically crafted for you. The point is this comment is dead wrong, as is most of the stuff you post lol. Literally any braking costs fuel. Go drive with your parking brake on if you really want to prove that ��
Math I can get behind
https://imgur.com/gallery/oQYRV
Coasting = engine braking
Coasting is when you take your foot off the gas pedal and begin to gradually slow down as you drive. As long as the clutch is still engaged, the connection between your engine to your wheels is still maintained. During this time your engine goes into a fuel cut-off mode where it essentially operates in reverse, with the power coming from the wheels to the engine. This allows all your car?s accessories (like you?re A/C, alternator, coolant pump, etc.) to continue to run without using any fuel!
You literally just told me that if you don't engine brake, the car will go a farther distance. My statement is saying the same thing: If you don't engine brake, the vehicle goes farther (slows down slower)
So how can you say its wrong when you literally just used the same exact example with a shut off fuel pump
You're missing it lmao
Are you confusing coasting while engine braking with coasting while in neutral? I hate to see you like this.
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