[ShapeShifter]

From my experience the afr will be more geared toward emissions. I am unsure if the grom will have power enrichment or run open loop fueling at wot. Anyone have any facts?

Unfortunately, not yet. We are all hoping guys like you and Brian S can spend some of your time educating us carburation guys. Once you have a Grom in your hands, will you be able to find out the questions you ask?

 

[ShapeShifter]

All most all EFI systems monitor:
intake temperature, intake pressure and air density - what kind of day is it, IE, hot & muggy, cold & dry, how much air is being sucked in by the engine
crankcase oil temperature - does the system need to be enriched for start up
throttle blade position - closed idle, mid throttle, wot & the throttle is pegged
air flow in CFM - cubic feet per minute - I don't think this system has this - my bike is still 2 weeks away
ECU - with a closed or open mapp - calibrated at the factory to pass emissions, etc
Lastly - a narrow or wide band O2 sensor, calibrated to 14.7 air fuel ratio, for the cat./emissions system

The ECU sends out a signal based on all those inputs, and opens the injector circuit for a predetermined pulse width
......

Thanks very much for any input you can offer us, Brian!

So given what you are saying above, if the ECU reacts to the array of sensors, will a larger discplacement kit and a different cam effect any of that? Or will the ECU simply adjust to what the sensors are reading (which may not be very different than stock displacement if its mainly reading ambient conditions)?

 

[ShapeShifter]

Tacos and ice cream. You are indeed an engineer.

 

[ShapeShifter]

I hope all this helps. It appears that we have some great people on this forum. It's all just starting, what a great adventure, we are at the start of this new product. Between all of us, I'm guessing there isn't much we can't figure out.

Thanks very much for your input Brian.

This leaves us carburetor tuning people swinging in the wind. Souping up Monkey bikes is just a hobby but I have never met a Monkey bike that I couldn't dangerously overpower with my own set of skills. Im used to tuning my own mini bikes with jets and needles and things so being at the mercy of aftermarket companies who may (or may not) develop something for the Grom is kind of unsettling.

You mentioned you may be developing something for the Grom. Would you need a significant market to make it work for you or would you do it as a "hobby" sort of effort?

 

[ShapeShifter]

There is "stuff" in the works. I purchased the Grom for product development, and fun. That said, I don't have the bike, just like you guys. I will dyno it after about 100/200 miles on the clock. I will also weld a O2 sensor onto the existing pipe, so that we can see the mapp as we make a few runs. I may just purchase a full system from someone, add a O2 fitting and get a base level idea what the exhaust change does. I don't think I have enough time to weld up a pipe before the first dyno test, we'll see. I'm looking to see if I can get "J" bent tubing that small, to fab up the first pipe. It just makes it much easier to do.

I just got off the DynoJet web site, looking at the Honda PS125 controller.
It's pretty much what they will build for the MSX125, and it uses the Honda narrow band O2 sensor, re-programing the system for 13.6/1 in the closed mode, but you can change it if you want. It should work for most riders. They do not say what it does in the open mode. I'll email Scott at DynoJet tonight and ask. The bad news is that the unit is $249.00 retail, steep for a Grom rider, who only paid $2995.00, not $10,000.00.
Brian S

Cool.

You talked about exhaust. What are your thoughts on un-corking the intake along with a more open exhaust?

I once had a guy re-program a stock GMC Suburban ECU for me. I use it for towing and wanted the most oomph I could get. He asked for simple data and built a program that was made for my application. The data I fed him was engine size, tire size, final gear ratio, and if the exhaust and intake were modified to move more air.

Is this the kind of data that a motorcycle ECU program can use to maximize performance?

 

[ShapeShifter]

Brian S.? Is there a Brian S. in the house.....?

 

[ShapeShifter]

I have been talking with the guys at Dobek Performance about the Grom tuning conundrum. They have spent some time analyzing their test Grom and have extracted some good info. Though they are still working on developing a quality controller for the Grom, they were able to tell me a little about where they are as of today.....

"The narrow band O2 sensor doesn’t seem to be doing much at idle or during acceleration. At WOT, however, the ECU goes into a closed loop fueling program that relies on the rich/lean readings from the narrow band O2 sensor. When you unplug the narrow band O2 sensor, an engine light turns on at WOT, and the ECU doesn’t know if the Grom is running lean or rich from its WOT target AFR. When this happens, the Grom’s ECU is compensating by adding more fuel than it needs. From what we saw, the AFR richened up to about 11:1, on average....."

“......The Honda Grom narrow band O2 sensor will need to be bypassed. On a stock Grom, when the O2 sensor is disconnected and the rider goes full throttle, the Grom enters closed loop and the engine light comes on. At this point the Grom enters an alternate fuel map, which richens up the AFR to around 11:1. Rich enough that it will foul the spark plugs eventually. In order to run a fuel controller effectively, through the entire power curve, something will need to be done about the narrow band O2 sensor.”

-

I am an EFI noob but it seems like Honda set this up bassackwords. Doesnt it make more sense to go to open loop at WOT? I need to read more.......

 

[ShapeShifter]

I have a hard time believing this is the case to be honest. Just because it goes rich when you unplug the 02 does not mean it was running closed loop otherwise.. any real data to support this theory?

Sent from my SCH-I545 using HondaGrom.net mobile app

This came up in a general conversation with them. I have no reason to belieive they pulled it out of thin air.

Have you had a chance to use some of your own equipment to do any sort of analysis?

 

[ShapeShifter]

Just for the record, I am not Pitbikers GF.

 

[ShapeShifter]

Thank you for the suggestion. We are actually experimenting with that right now. I think we may have a way to work with the narrow band O2 instead of bypassing it. The next challenge is finding the OEM plugs. Considering the fact that its a plastic plug, its pretty nuts how much they can cost to buy or make. We may have to offer a tap on system before we offer the OEM connectors, just to save us and the consumer some cost. Almost there, thanks for the suggestions and patients.

Great news!


I know your EJK controller is adjustable and "load based". Will come with a specific setting out of the box, or is it "neutral" or "off" when first installed? Will it claim a certain performance gain, i.e. "1.5 HP over stock" etc....how would that even work with a load based system....?