Acceleration ramp modification anyone ?

Hi all,

When accelerating from still, the cas applies some sort of ramp-up on the available power, until maybe 20mph.
Under that speed, full power or even full torque are not available no matter how you floor the pedal.

Has anyone figured-out how to have that ramp/curve modified ?

In some situation, I could use a snappier acceleration from still. I understand the concept but IMO they have done too much


Thanks

That is one of the most requested mods. I drove a LEAF the other day, and not having the ramp makes a considerable difference.

Unfortunately, this is not something that can be changed by the MUT-3 tool, and requires the programmer used by the developers of the i-MiEV, something that we don't have access to.

This sounds like good ole boy hotroddin'--so count me in...

Does anyone know if the ramp feature is some sort of current limit or a speed/accel limit?

If it is a current limit, is it related to an electrical component load limit (e.g. pack, inverter or motor), or some mechanical torque limit (motor shaft, spur gears, differential, CV shafts), i.e. What is it trying to protect and how much margin is available?

If it a speed/accel limiter, then why is it there and what/who does it protect--the driver, pedestrians, or the factory?

I would bet it's a limit to protect something - If not just for the limit of the traction of the tires, then the strength of some mechanical component (reduction gearing, axle shafts etc) or possibly it's a current limit protecting some electronic component - The motor, the inverter etc. *If* you could make a major change to it, you might find the limit of all three ;-)

Who knows how much margin is available?? Mitsu doesn't seem ready to give us an 'Insane Mode' anytime soon :lol:

Don

Given that once you get up to 25 mph, you have all power available, I'd say it's for making the car easier to manage on takeoff. Like the ASC, it's slightly overdone. If they were protecting components from instant torque, the ramp should disappear at 5-10 mph, not 20.

I agree, the ramp makes it tough to start out uphill with a car full of people.

Early in the game, I became convinced that our red needle is simply a damped ammeter and not a power (volts*amps) gauge. I believe the ramp-up is merely limiting the current.

That ramped acceleration is infuriating - one of my Sparrows has a five second ramp-up, which was a conscicous effort to keep from breaking the Harley-Davidson drivebelt with a lead-acid pack - it's dangerous when pulling out onto a fast-moving highway. My two lithium Sparrows have zero time delay, and it is such a pleasure to be able to modulate those slingshots myself. Because of their light weight, no more snapped belts no matter how fast I accelerate. Here's the video of Llewellyn using Insane mode in the 31 July 2015 P85S review? https://www.youtube.com/user/fullychargedshow

Anyway, I would love to see a hack which would alter the i-MiEV acceleration response curve and, while we're at it, give me 150A regeneration in B mode and give me zero regeneration in D. That alone would keep me from still doodling with the idea of my own custom ultra-aerodynamic 100kWh long-distance EV with a programmable controller...

What a shame we can't change what's been overdone by Mitsu
It's just a darn parameter :roll:

it's slightly overdone

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Slightly.....more like drastically!

In a peppy.... (ok I'm reminiscing the time I had a 700kg hatchback with 200hp) But in any ICE car You can give the engine some RPM and make the inertia of the clutch, flywheel and rotating motor mass work in you favor. Giving you that shock - slingshot style take off even in the most asthmatic sluggish ICE car. A good lump of RPM and dump the clutch = slingshot to some effect. Sure you don't have full torque at low rpm but if you want to take off quick you don't let the clutch out at low rpm.

Now with Imiev the advantage with the electric motor full torque at 0rpm. Sure but if they don't let you have full torque (or at least a good slab of it) then really have no advantage. Just a embarrassingly slow car at the lights. Not to mention a car that cant climb the concrete step up into my garage from a stand still.(ICE car has the same issue but you can give it some RPM and a blip of the clutch and you hop the front wheels up the lip. I have had people in ridiculously slow cars. Like old diesel trade trucks/utes loaded down with gear and 5 people on board. Drag me off at the lights. Just because they are able to dump the clutch and get that first head start. While the Imiev is strangling hell out of itself with 500mah of current flow not allowing that amp needle to swing to the right and let any juice to flow into the controller.

Rolling starts are not to bad but still nothing spectacular. I think the limp wristed softy at Mitsubishi Motors who programed that sluggish soft start should get the sack. Get some one in who can tweak it up a bit. Make the Imiev lift the front wheel a little:lol:

Perhaps tricking the speed sensor that your actually traveling a 20mph. I'm sure that would open up new big an of worms with other flow on issues. I don't think you would break anything on the car with a more aggressive ramp up . You would just spin the back wheels or activate Traction control befor anything broke. The car is to light and the tire package is to narrow. Im sure even the Tesla model S has a progressive ramp on take off (as in just shorting the battery - controller -motor as one = trouble for mechanical and electrical components) But its way more aggressive than the Imiev. (not to mention it has a lot more to be aggressive with)

The sluggish acceleration of my Meepster is probably the one single issue that prevents me from completely and thoroughly enjoying my iMiEV. In my daily commute, there are countless instances where I need to aggressively get up to speed (for myriad reasons), and my Meepster just doesn't have it in her. I really dislike, er, no... I'll say HATE, the overly-restrictive acceleration ramp that Mitsu built into the iMiEV.

I know I've read many threads and posts on these forums where other iMiEV owners have touted their ability to beat ICE cars off the line. The longer I've owned my iMiEV and the more experience I've had with its dreadful off-the-line performance, the more I realize these other iMiEV owners are either a). lying about their off-the-line performance, or b). have totally deceived themselves into thinking their off-the-line performance is better than it really is. A third very likely option is c). other iMiEV owners are just too afraid to say anything bad or hurtful about their cars and instead embellish the performance in order to make themselves feel better.

I've posted this before, but I believe there are certain conditions that must be met in order to beat anyone off the line in an iMiEV:

1). You have to catch the other driver totally off-guard. As in, they weren't even planning to try and beat anyone off the line, least of all a funky-looking EV.
2). You have to anticipate the green light and react much faster than the other driver.
3). The other car has to be a total beater.
4). You're the only car sitting at the light!

Are you driving in 'E' gear? if so, try 'B'. If the power needle is not buried over on the right hand side when you are accelerating, then something is not working right, also push the pedal to the floor.

In these instances I'm speaking of where I need aggressive acceleration, I am always stomping the accelerator to the floor. When the go pedal is mashed to the floor, it doesn't matter which gear you're in. You always get full power. My problem is the iMiEV's "full power" is not very powerful for the first few seconds of acceleration when it really matters!

RobbW said:

I've posted this before, but I believe there are certain conditions that must be met in order to beat anyone off the line in an iMiEV:

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Here are some other conditions. The other car must be at least one of the following: All the Audi 5000’s, Dodge Caravan, van, Ford Escape, E250, Ranger, Chevy S10, van, Honda Civic, Hyundai Santa Fe, Jeep Wrangler, Lexus HS, VW Jetta (there’s more but I forgot). These are the cars that want to beat me to the next red light and get in front of me; but they can never make it … too much fun . I wonder if they can read my mind "Get behind sir. No cutting. I was here first. Can't you see there's no one behind me?".

I’ve never had troubles merging onto fast highways out here; and they are fast! So out here (Rocky Mountains) acceleration has never been an issue.
Oh and BTW, this iMiev way out does my Prius's on start-up acceleration (definitely not passing acceleration). I am so used to my Prius's, that now I feel like I'm in a zippy car!

-Barry
-May we all own a Tesla one day

Well, I know I like to promote the i-MiEV as much as possible, but I do recognize its shortcomings. But even with the overly restricted low-end, I have matched two different Camaros coming from a dead stop, at least up to 42 MPH. The thing is, even with de-rated acceleration, we can put more instantaneous power to the road at takeoff than most ICE drivers. In order to avoid spinning out, ICE drivers can't simply punch it or pop the clutch. Doing either almost always results in tires chirping and possible red-lining with an automatic transmission. So, while they ease into it to get rolling and then pour on the power, our i-MiEV has automatically done this for us in a smoother and faster fashion. Granted, being more attentive and responsive to the light turning green makes a huge difference, but holding a Camaro ZL1 in a hurry up to 42 MPH before finally being able to pass me says a bit for the delay in takeoff and shifting of ICE vehicles.

Also, pointing uphill vs. downhill vs. level, makes a very big difference, as does weight. Me alone at 175 lbs. with nothing in the car is much peppier than with a load or passengers. Pointing uphill from a start, forget trying to outdo the other person if they're paying attention. Level ground, pretty good. Pointing downhill, bye bye, 50 mph in 4 seconds. (I'll update this to verify after leaving work. )

In my typical daily commute, there are three intersections (in each direction) where two lanes merge down to one lane within a few hundred feet after the stoplight. So, every single day, I have up to six opportunities to try and beat an ICE off the line before the merge. Most often, the stoplight is green as I approach and go through the intersection. So there's no racing off the line in those instances. When I am stopped at a red light, I'm usually not the first in line. So, conservatively speaking, I probably get at most one (maybe two if I'm lucky) opportunity per day to demonstrate my Meepster's abilities. Having owned my iMiEV for over two years now, I think I can honestly count on one hand the number of times I've beaten an ICE off the line. And each of those winning times, my conditions for winning (which I listed in a prior post) have always been met.

BarryP, to be honest, would you say the times you've won off the line it was a real race? By that I mean both you and the other driver had your go pedals mashed to the floor and there were no obstacles or impediments preventing a full, complete, and fair "race"? Here's what happens in almost every off-the-line opportunity I've been involved in. It's pretty much always a scenario where drivers are racing to be the first to the merge after taking off from the stoplight. Since there is a very short distance to the merge, it can never be a "true" race where each driver has clear, unimpeded track all the way to the "finish line." Someone eventually (very quickly, actually) has to give in and let the other car merge. So, in my case, it's never really a matter of beating someone off the line as much as it is realizing (in a very short amount of time) that this is stupid and can get dangerous very quickly.

In these situations, unless you or the other driver are complete, total jags and are hellbent on running the other car off the road if necessary, someone usually lets off the accelerator, eases in with the other traffic, and just goes about the remainder of the commute. A long time ago I had detailed in another thread an instance where I raced a pickup driven by one of those complete, total jags who did not take very kindly to me trying to beat them off the line. Since then, I rarely ever try to race anyone. And the few times I have gotten the urge since then, I have usually lost or had to give in. It's just not much fun to try anymore because of the real and credible likelihood that I'll embarrass myself in my Meepster.

Now, if someone could develop a mod/hack that would give our iMiEVS "Insane" or "Ludicrous" modes, then I'd be stomping the go pedal off every red light and taking deep personal satisfaction in seeing other drivers' faces turn red in anger/embarrassment (in my rear-view mirror, of course)!!!

RobbW said:

BarryP, to be honest, would you say the times you've won off the line it was a real race?

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Of course. And it’s as you described. But I can tell if I’m against a road rage guy --- and then it’s obvious to back off. Some of the typical races are when I am at a 2-lane stop light. And I can see the right lane ends in 50 yards so obviously stay in the left lane. Then a Ford Ranger pulls behind me; changes his mind, and pulls next to me… If not a road-rage guy, I can’t remember a single time someone beat me. What’s sad is when another car pulls behind me. Then that car and the Ranger has to dual it out.

I did embarrass myself one time. My neighbor came to my house and said “Barry, I was trying to pull up next to you and wave high. And then you disappeared!” oops. Now I’m more alert in those situations.

For the record, I’m 150lbs.

-Barry

Howdy Robb,

So you obviously know the drill and from your merge zone don't really have a good place to rise and shine without it getting risky--but off the line up to 40 mph these little jelly beans are really quick and easily leave most other cars to catch up.

i have a couple of longer merge lanes after the lights that i just slow down and give way even if i beat them off the line, primarily because there is no top end to play with and i would have to exceed the posted limit too much to beat them and i still want to have plenty of range for driving around.

In my experience most ICE drivers are oblivious to the speed limit and road and weather conditions--it's either all brakes or all throttle regardless of whether they are on the interstate, county roads, or in my neighborhood.

i've never seen a cop accelerate slowly from a redlight--it's not their car and it's not their gas, so cop off-the-line it's all haul-ass. But i have outdragged them every time off the light and up a slight grade, up to 40-45 before they come flying by. Happens about once a week.

Now if i had a second Kiev or the control module to snoop the CAN bus and play around with then my first mission would be to liberate the ramp...

kiev said:

--but off the line up to 40 mph these little jelly beans are really quick and easily leave most other cars to catch up.

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Think you mean from 25 mph and up to 40 mph, right?!

I know that I could beat my 'i' with my F-350 diesel off the line by throttling it. I may blow out black smoke - which is fun when you have some assH behind you, with the windows open -
My truck has a HUGE lag when you go off the line. It is like counting to 5 and then it goes.

Sorry 'i', but even my truck will beat you off the line .............. maybe not in the long run, but off the line for sure for a hundred feet

tigger19687, inasmuch as I have been coal-rolled by someone who presumably took offense to my "100% Electric" bumper sticker, I hope your tongue was in your cheek when you said that (and, yes, my windows were open). It's the antithesis of what we're all about, IMO.

Just a reminder, this thread is specifically about exploring ways of modifying the i-MiEV to allow immediate full-current application, without the programmed-in 2-3 second time delay.

Per the Technical Information Manual, it seems that the acceleration ramp is purely for ride comfort. This, combined with a slight dampening of the throttle, are used to provide a smooth yet responsive ride.

Seconded, coal-rolling ain't cool.