Honda Grom banner

Aftermarket ecu

17K views 65 replies 9 participants last post by  Wibbly 
#1 ·
I am going to go with the 181 neo. I have done research on this and my first instinct is to get all dyno jet. I want plug n play. I want the most data I can get on the handlebar monitor/gauge. I want wb autotune, of course.

Now.. I see you guys like Aracer, and there’s options there.

So.. let’s hear what you think. My initial goal is to haul my 230lbs. uphill against the wind at 60mph at 75% throttle.
 
#4 ·
I am going to go with the 181 neo. I have done research on this and my first instinct is to get all dyno jet. I want plug n play. I want the most data I can get on the handlebar monitor/gauge. I want wb autotune, of course.

Now.. I see you guys like Aracer, and there’s options there.

So.. let’s hear what you think. My initial goal is to haul my 230lbs. uphill against the wind at 60mph at 75% throttle.

Look up my build.
 
#5 ·
I got the Yuminashi ECU and installed it yesterday. I only took it for a short test ride so I can't tell if there's any difference yet. However, the bike starts idles and runs just fine with it. :)

 
#7 · (Edited)
Sounds good so far, can’t wait for further testing.
I'll be sure to post a detailed report after I've put some miles on it. It's really fun trying out stuff like this. :)

I am a noob, but it seems we’re just trying to program it rich enough not to blow at 90%-WOT and not too rich at lower rpms.
Yes, that's also my understanding.
As far as I know the Yuminashi ECU operates the same as the stock one, except it isn't restricted by US emissions regulations and can self tune the ignition and fuel trims to accommodate a wider range of modified engine parameters. It's very tedious repining the connector. but with the wires in the right sockets it works fine. Also the Yuminashi has no rev limiter, but that doesn't matter to me because I don't spool up the engine anyways. ;)
 
#9 ·
Yuminashi:

"There is a chance that your bike won't be spot on from the first time you start your bike since it's capable of self adjusting fuel trims and ignition tables while you ride to deliver an accurate and safe performance, it is a completely autonomous system....no more software updates, data cables, laptops, secondary sensors, building/searching or asking for maps needed.
It will automatically learn and store the adjusted fuel trims and ignition tables by itself using the OEM O2 sensor already on the engine.
So keep in mind that the first kilometers/miles you drive your bike/ECU will be in learning mode."
 
#10 ·
The oem o2 sensor can only show rich, lean, or stoich.

It cannot show how rich or how lean.

As such tuning with it only allows one to tune to stoich. This is fine for low rpm operation or low throttle openings. It is not fine for higher engine loads. Stoich is too lean

This is why the oem ecu uses closed loop only partially.


There's no way you're getting a complete auto tune with a narrow band o2 sensor.
 
#16 · (Edited)
pretty well all cars today use wideband o2 sensors. this allows them to tune to AFRs that are NOT stoich.


the main limitation with narrowband is that it cannot report anything but 3 conditions. as such you can only control to stoich. if it's lean you richen, but you don't know how much. if it's rich you lean the mixture, but you don't know how much. narrowband tuning is basically just a hunting signal. the ECU looks at this signal over time to figure out about where it's stoich. then it uses this value to control the mixture.


this is ok for economy, but when you require larger throttle openings these values aren't used and the vehicle goes back to open loop (this is what happens when you have a CEL for an o2 sensor, the car stays in open loop full time and economy suffers as the mixture isn't being leaned to stoich). a stoich mixture will not produce good power, and will produce a lot of heat in the engine. this is a death sentence for a grom.

the stock GROM ecu does exactly this, as does the yuminashi. it will run closed loop when it's safe, and when it's not safe it will fall back on to the open loop mapping. since you don't want stoich in these areas, the ecu won't be able to optimize the mapping for these rpms and throttle openings. hence the WB tuners you can get from companies like bazazz and PC

but with new vehicles using wideband, they are able to tune to any AFR they like in closed loop. you could never do this with narrowband.
 
#20 · (Edited)
the stock o2 sensor cannot report that AFR


yuminashi is likely just loading an open loop map in these ECUs, hence the "you must install the right injector" because the ECU cannot actually verify the AFRs and adjust pulse widths. because of this they depend on a larger injector to deliver more fuel, instead of the ECU adjusting pulse widths (it can't, because it is without feedback)


using the stock o2 sensor the ECU can only tune to stoich. their "target AFRs" in open loop will be based on their mapping. the stock grom ECU does the same.
 
#21 ·
Could they just be using the stoich voltage of the narrowband o2 sensor to equal 13.2:1 instead of 14.7:1 in the ecu then when it goes rich/lean it tunes back to the 13.2:1 (kind of simulated stoich if you catch my drift) or are you saying it’s just like using a pcv without the wb2 so anything under 60% would be 14.7:1 then over 60% it would go to 13.2:1?


Sent from my iPhone using Tapatalk
 
#26 ·
A narrowband o2 sensor cannot report actual afrs.

If you offset the voltages that does not give you actual afrs, it gives you a "richer than stoich" or "leaner than stoich". Not actual.


This is why companies use wideband sensors. They can tune to actual values.



Without proper feedback, a control loop cannot match the output to the setpoint.

The feedback from the narrowband is two values very near stoich. One above and one below. By fueling such that time spent above equals time spent below, then averaging the output, the computer can figure out what value produces stoich.


If the feedback to the ecm does not indicate actual AFR, then the system cannot output to actual AFR.
 
#36 ·
Wibbly...... Stop reading enginebasics.com and forget what you think stoich means to the sensor.

An ECU reads sensors in voltages... nothing more, not even "AFR". Narrowband is an oscilating 0-1v and Wideband is a linear 0-5v. "Stoich" isn't a magical value narrowbands and widebands just know. The stoichiometric combustion of fuel and air, noted as AFR mind you, is an understanding WE as humans understand, and Narrowbands/Widebands are our TOOLS used to measure where we are RELATIVE to "Stoich" in voltages. Stoich serves as an index for us to tune relative to. Narrowbands and Widebands just vary greatly in their abilities.

When programming the ECU, WE determine from the voltages read from the sensor, what the ECU needs to be targeting in X condition. Despite the sensors being completely different in their capabilities and how their voltages vary, they both serve one function and that's providing feedback to the ECU.

Let's say the stock ECU is programmed to target a voltage(lets assume .5v) which we could roughly translate to 14.3 AFR. So, the ECU is going to use .5v as an index between rich/lean and the sensor is just going to do it's thing and provide voltages to the ECU. So while these voltages swing back and forth telling the ECU in respect to .5v if it's rich or lean, it has to pass over the fuel table cell and trim quite a few times before it "learns" it's finally experiencing the requested(.5v) condition more often than not. Ever play the game Hot/Cold with someone? It's like that. This process happens fast in real time, but relative to a wideband that provides accurate linear readings, it's a slower process. There's a lot more to the sensor itself, conditions, and it's chemical makeup that allows it to read gasses vs oscilating voltage, but this is the best way in layman's term I can describe.

So bring in the aftermarket ECU that claims "13.2 AFR" which, let's assume, translates to .7v. Now the ECU is programmed to target a voltage of .7v. Narrowband is doing it's thing, swinging it's voltages back and forth playing hot/cold around the .7v index the ECU is indexing, until it again sees this condition more often than not.

TA-DA... this is crudely what we call "self-learning" within the closed loop using Narrowband. Not the best way of accomplishing fuel trims by any means, but "it works" and that's proven- there's NOTHING to debate.
 
#27 ·
The factory ECU is "self learning" just as much as these yuminashi ones. In fact I doubt they changed the open loop fuel maping and even if they did, there would be a very small chance that it would be the correct map for the exact modifications that have been done to one's bike. I think the term "self learning" is a bit vague.
 
  • Like
Reactions: Wibbly
#28 ·
Awesome info. Thanks, now I understand a little more. I was drawn to dynojet, but it seems Aracer is the choice of the super high performance guys. I said seems, I know some of the heavy hitters use dynojet. The local dyno is dynojet, but I am going to get the RC1, their AF1 autotune, and the iMode. Should I install the 181 neo first? Problem is, I want my bbk afr to be correct from day one so I might want the aftermarket ecu to be up n running. Btw, I am looking for contrary opinions. I like the Pod 300.
 
#33 ·
You'll need the tuner first before the NEO 181 gets installed. The factory ECU by itself will in no way be able to give that bbk what it needs :encouragement:
 
#29 · (Edited)
I've been riding around all day running errands and the engine revs a freer at high rpms, likely because it's getting more fuel at high rpms. Overall the throttle is more crisp and responsive even at low rpms, probably from the different ignition timing curve. The bike keeps up with traffic easier without having to wring out the engine. Comparing the Yuminashi to the stock ECU, it seemed to have been holding back the engine at high rpms. It took a few cold starts and about 60 miles of riding for it to dial itself in. During that time the engine ran weak, but that quickly passed. I'm quite pleased with how this is working out. Still running the modified stock exhaust on it for this week to log some gas mileage. It makes a nice compact little package tucked under the engine with nothing sticking out anywhere. I like it. :)

Land vehicle Vehicle Motorcycle Car Motor vehicle


Land vehicle Vehicle Motorcycle Automotive exhaust Car




After that I'll put the TOCE exhaust back on to see what happens with it. :)
 
#30 ·
Thanks for posting. How much re-pinning was involved? I am tempted, but then I am planning on going to an Aracer in a few months. I have an aftermarket pipe and the chimera intake. I am running 16f and 32r sprockets. And a lot of expensive stuff that doesn’t make it faster.
 
#31 ·
It requires relocating 4 pins which is tedious and takes some time, but if you're going big block and all that other stuff everyone else does, you're better off getting something else. The different Yuminashi fuel map and ignition advance curve are definitely less restrictive than the stock ECU... which is exactly what I want... something I don't need to fuss around with. It works great for me because I'm a daily utility transportation rider who needs something to take me from here to there cheaply... and the Grom is absolutely perfect for my uses. My current gas mileage average is 138.8 mpg. :)
 
#40 · (Edited)
tooter you are just willfully ignorant. you make claims based only on anecdote and provide zero actual evidence, and then plug your ears and scream the moment anyone challenges you. you must be old.




farkas, this is what a narrowband o2 output looks like






can you show me how the ECU is going to target 13.2:1? you can see the average output of the sensor is around 0.5 volts. the oscillating happens around this voltage (which happens at stoich)


devices like the EFIE simply modify the sensor output (by adding or subtracting some voltage to or from it), in essence this "shifts" the switch over voltage so the ecu will compensate. however you don't know at which AFR this is actually happening without feedback from a wideband o2 sensor. if you were to subtract 0.2 volts (make the ecu think the bike is lean), your new sensor feedback would be between -0.1v and 0.7v, the average of the two being 0.3v (lean) and the ecu would then add fuel to lift that back up again.




thankfully, a wideband o2 sensor provides a linear feedback across all AFRS so the ecu can easily pick a point on the line and control around that one.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top