[MrEvilpirate]

Here it is long overdue, my findings after widebanding the Z and messing around with O2 signal voltage.

First some corrections to my first wideband readings post as I have spent a lot more time watching the gauge and know more about how the bike runs.
----------------------------------------------------------
Stock the bike cold idles at 13 and warms up to 14.6 +/- 0.3. So as the ECU adjusts the AFR based on O2 readings it oscillates between 14.3 to 14.9. One thing I noticed is after you blip the throttle or get off the gas AFR at idle drops to about 13.8, then slowly climbs up to 14.6 over about 15 seconds. I think they do this to keep the mix rich in case you start again quickly... richer mix can make up for no spark advance.

Cracked Throttle cruising is same as idle (both closed loop) around 14.6. "Dig in" a bit, maybe 3/4 throttle it drops to 13.3ish. Any revs, regardless of throttle position, over around 7k and AFR drops to 13.3ish. WOT gives you AFR of 12. So the bike runs rich stock, except at cracked cruising, where it can get a touch lean and in my experience cause some surging at mid RPMs.
----------------------------------------------------------
Enter EFIE. I ended up with a voltage offset around -0.195 v.

After learning some trims, cold idle is now 12.8. Warm idle does the same raise up over about 15 seconds. But with EFIE correction it is about 13.1 (right after a blip) and settles around 14.2. This eliminates the surging I was complaining about. Cruise/cracked thottle is in closed loop... O2 signal is offset, so AFR for this range is same as idle, about 14.2.

3/4 throttle and over 7k RPMs about 12.9 and WOT is 11.8-12.0. So EFIE's modulated signal caused fuel trims to be learned as richer than without EFIE, this translated into richer open loop settings after the ECU learned the trims. PS all these numbers I'm giving you are after starting and stopping the bike many times (cold starts) and running about 100 miles at each setting.
----------------------------------------------------------
With EFIE and Intake:

Cold idle back up to 13... intake leaned EFIE mix from 12.8 back up to 13 cold idle (open loop)

Warm idle (closed loop) the same as just EFIE at 14.2 (with 15 second dip to 13.1 after blipping throttle)... ECU can handle intake and richen mix to get to it's target AFR no problem... remember EFIE is RICHENING the mix, so if ECU can hit target with EFIE, stock ECU can handle intake in closed loop without it as well.

Cruise/cracked throttle is closed loop, so same as just EFIE 14.2.

3/4 throttle or above 7k 12.9 - 13.2. So even though ECU learned trims, when applied ECU does not get stock AFR with intake at this throttle position. But this is safe range. Remember... EFIE is used in this example and is making the ECU learn trims that are richer than would be without it. So even though this is open loop, by using the EFIE in closed loop more extreme fuel trims (richer) have been learned.

WOT 12.2 - 12.5. Again intake is shown to lean the mix.
----------------------------------------------------------
EFIE, intake, and pipe

Cold Idle - 13 (note pipe did not lean the mix more than just intake. These parts flow more air the higher the RPM... so at idle they flow a little more than stock, but when ripping hi RPMs they flow a lot more than stock... part of the reason why learned fuel trims can't accurately maintain stock AFRs at higher RPMs or more open throttle positions... because the trims are learned under closed loop conditions, where performance parts perform closer to stock, in terms of how much air they let flow through).

Warm idle - 13.1 (after blip) up to 14.2.
Cracked Thottle/Cruise - 14.2. This proves stock ECU can handle intake and exhaust and provide stock AFR levels during closed loop operation. Again EFIE is used in this example. Without it the ECU wouldn't need to send as much fuel, so stock is the same thing you will get stock AFRs in closed loop.

3/4 Throttle and over 7k rpm- about 13.3. Leaned out a touch more than with just intake. Still safe. Again with EFIE.

WOT - 12.4 - 12.7. So check this out. Honestly I think it pulls harder closer to 13 than 12.
-----------------------------------------------------

FINALLY - NO EFIE, STOCK ECU, INTAKE and EXHAUST:

Cold Idle 13.3
Warm Idle (after 15 second rise) and cruise/cracked throttle 14.6
3/4 and above 7k - 13.9
WOT - 13.3
----------------------------------------------------------

Thoughts

For stock bike without fuel controller and adding intake and exhaust, it looks generally safe, with the following caveat:
Richer mixes run cooler. Kawi set this thing to run rich at WOT, partly I believe to control head temps. I don't know enough about AFRs to tell you if it is safe to run this type of motor for long periods of time WOT at an AFR of 13.3. It seems OK. 13.9 at 3/4 seems a touch high though.

EFIE seems like a good cheap add to the bike to get more fuel flowing if you want to run these mods.

Personally I would run it even on a stock bike, especially if the surging at mid RPMs when rolling on from cracked throttle bugs you.

For Kaw'ee and guys running O2 deletes, be advised that the "closed" loop without the O2 tends to run lean. I was seeing numbers over 15. This was on stock bike. I didn't take readings with mods. So at idle or cracked throttle/cruise, without O2, you are lean. It does richen at 3/4 and WOT compared to stock. I suppose that cracked throttle AFR being lean MAY be acceptable because there is minimal load on the engine. When you decelerate the mix leans out to the point where it can't be measured on the gauge... but I personally would not be comfortable. Kaw'ee... I think you mentioned your idle temps went up when you deleted the O2. This is why.

Personally If I were you guys with no O2 I'd just weld the bung on and call it a day.

It's late I couldn't sleep and have been wanting to get this out.. I didn't proof it and it is a wall of text. Hope you can get something from it. Happy to answer any questions to the best of my ability.

Think I'm ready to turn the page on this one and put the wideband away. Now we know.

 

[MrEvilpirate]

TBS- you pretty much got it bud. Run that pipe and don't look back. Bike will be fine.

Next spring I'm going to put my stock airbox back on and try running with just the pipe. But I will personally keep EFIE.

Even in stock configuration, my experience is that EFIE improves the bike's fueling... but my results show you don't need it to keep AFR in safe range.

Keep the shiny side up brah!!! lol

 

[MrEvilpirate]

Ando I had a great post and lost it. So I've taken a couple days and I'll post complete findings soon. Long story short intake and exhaust lean out the mix in open loop. Still fairly safe but bike runs much better using EFIE mod, target voltage for me is 0.195 V but YMMV... EFIE is a good idea. Full results soon...

I have numbers stock, stock and EFIE, intake only, EFIE and intake, EFIE intake and exhaust.

 

[MrEvilpirate]

Greg- You're probably right. Grom guys said 0.250 was about the limit.

Here is my install write up for anyone interested:

https://www.pdfhost.net/index.php?Action=Download&File=d2f4366e2f4f519630bf5646f69faf98

 

[MrEvilpirate]

OK boys we have proof of concept.

CEL was out today so I dialed up EFIE to a 0.125 V offset and went for a ride. This was without clearing any trims.

I noticed that cracked throttle cruising AFR dropped and I was seeing 13.7 and 13.8 for the first time. The AFRs swing around, stock is like 14.4 +/- 0.4. With this offset I got to maybe a 14.2 +/- 0.5. There are couple things coming into play here.

First, trims were not reset and the ECU most likely needs more time to re-learn. I only went for maybe a 6 mile ride.

Second, as narrow band O2s get farther away from an AFR of 14.7 accuracy drops of QUICKLY and a smaller change in voltage can correspond to a larger change in AFR. This doesn't worry me too much... AFR on carbs swings much wider than what I was seeing on my test ride today. The average AFR drops, but the "swing" could potentially grow with an aggressive offset.

So I went back to the garage, and with the bike still running, turned up the voltage offset while I watched the idle AFR drop. I got it down to around 13.3 and went for a ride. I needed an offset of 0.360 V to get there. Promptly threw code 33: bad O2 sensor. So I took it a bit too far. The offset must have sent voltage from the O2 out of range.

Rode home dialed the offset back to 0.250 and disconnected the battery. I'll take it out again tomorrow with no trims stored in ECU and see how it runs.

I will say this... even with just the 0.125 V offset... I was hunting around for lean surge on cracked throttle between 5-7 krpm and couldn't find it, so I'm optimistic. Still need to see how open loop is affected.

I have a zoom loop and a K&N filter for DIY intake coming, hoping to have both here by end of day Friday, and weather is looking good this weekend. So if the parts arrive on time the goal by Sunday night is to post up confirmation that stock ECU can handle exhaust and intake, and maybe even some tuning info on the EFIE.

One thing I think that may come into play, is that as we tune EFIE and get away from 14.7 AFR, because of the loss of accuracy, what may work on one bike may not work 100% on another, even with identical mods, due to accuracy tolerances of narrow band O2s. That's pure speculation on my part, but from what I read, and since we're pretty much asking the narrow band to shift lamda and almost act as a wideband, I think some variability between different O2 sensors can be expected.

Side note- apparently having the bike on (not running) with O2 disconnected will throw the O2 heater circuit code. Heater circuit is energized when key is turned on, and it is grounded through the ECU. I read that in some vehicles the ECU can "pulse" the ground to turn on or off the heater circuit. The code gets thrown if resistance (ohms) is out of spec, or if there is a short in the circuit, or if the circuit is open, which is the case when the O2 is disconnected.

 

[MrEvilpirate]

My reservation, after a lot of googleing, is that in some vehicles closed loop trim seems to affect the open loop map, but in some vehicles it doesn't. Based on the forum post I linked to it looks like the Grom will adjust open loop fueling to long term closed loop trims. We don't know that the kawi ECU works the same way.

I'm going to swallow my pride and take stock exhaust to the muffler shop and have them weld on a full size bung and spacer so I can use my wideband and take some WOT AFRs, then install install EFIE and try to get general AFR around 13.4. Take the bike for a long ride then check WOT AFRs... if they change we know we're good... and no lean risk as my bike is still pretty much stock.

Kaw'ee I think your plugs look just a touch rich, but way better than mine with stock setup. I'll throw some pics up of mine later.

Greg I hope you are right about how the trims get added to baseline on open loop... will save people a lot of money if this works.

 

[MrEvilpirate]

I've answered some of my own questions.

The system adjusts voltage across the board. You set in mA how much you want to increase/decrease. That change is applied to the entire fuel map. A lot of grom guys run this to compensate for exhaust and intake. I'm going to do it. Need to weld a bung on my stock exhaust for my wide band, will log before and after installing the EFIE. This seems like a good option for guys who want to richen up the stock lean AFR and add a pipe and intake.

https://docs.google.com/document/d/1wX0fOAMqEmYk6jgRK37Qc4apUxoLQw5pchcSt5krOFA/edit


Check out post 88:
https://www.hondagrom.net/forums/13-grom-performance/3113-o2-sensor-grom-piggyback-tuners-9.html

 

[MrEvilpirate]

Info is only good if it is accessible! Nice chart.

I thought it was really frustrating not knowing if you can run a pipe and intake without damaging the bike. So now we know.

I've gotten so much from forums in the past I'm happy to finally be able to contribute something and give a little back.

 

[MrEvilpirate]

I think making the bike think it is colder will initially richen the mix, but the O2 will be reporting back to the ECU and eventually "drag it back" like you say.

 

[MrEvilpirate]

Maybe some high temp RTV when you install the plug to help seal it up.

 

[MrEvilpirate]

LOL Ando at "must be an engineer".

I have a degree in jazz performance on violin and trombone. I freelance playing weddings and private parties and have a little computer business on the side. I work in construction as a day job. I just really like tinkering!

As for the Kaw'ee mod... do it! For safety! It really does sound a lot better than stock. I didn't drill hole into the chamber, just used channel locks like Kaw'ee recommended to pull out the tube at the back of the exhaust. It pretty much bypasses the 2nd cat. Only thing is you need to loose that silver exhaust tip type thing. Guess you could tack it back on. Anything beats the sewing machine sound though IMO!

 

[MrEvilpirate]

Greg - I thought about the different type of plug. No, we don't have titanium... Kawi gives the testing spec in voltage not ohms. Also, after just coming home from 2nd ride, I stripped some of the gray wire and measured voltage across grey to black with the bike running... saw oscillation between 0.1 and 0.9 V, so that one's put to bed... bias voltage confirmed! Bias is about 0.5 V, so the 0.250V correction with the EFIE shouldn't cause an out of range code. And yeah, wideband makes jetting way easier with carbs... especially the idle mixture screws. That's actually why I have this thing!

Shift light project looks really interesting!

Ando - LOL at communism being nice... in theory.

2nd run after "reset" in effort to clear CEL. AFRs are getting much closer now to my first measurement. The power off either clears the trims for sure or this is an insane case of placebo effect.

I'm getting a much better idea of how the ECU adjusts AFR based on throttle position and RPM combo... honestly it really isn't too bad. My only major gripe, after determining that there is basically zero risk of running lean (stock) at WOT is the lean surges you get occasionally around 5-6k RPM with throttle just cracked. More to come.

 

[MrEvilpirate]

Ando - by the way that print... my sister picked it up for me about 15 years ago at a salvation army!

 

[MrEvilpirate]

OK gents minor update:

Greg- Thanks for link. I actually read that same article last night. Lots of good info in there.

Ando - Some type of standalone hardware to log to honestly I'm not sure what it would take... and I would only have AFRs, not throttle position or RPM so not sure how useful it would be.

So far today before work: I confirmed continuity from all (4) O2 sensor wires back to end of harness right before it plugs into ECU. I also confirmed that the ECU is sending voltage to O2 sensor (bias voltage) which is why I had signal on the voltmeter over 0.9 volts and why Kawi tells you to pull voltage across the pos and neg (black and grey) wires, and not just black to universal ground. When in doubt follow the directions I guess.

Today after work: I had ECU unplugged all day. I left EFIE connected but zeroed the offset (Hopefully this is actually zeroing and not the "I washed my bike today and it feels like I gained 15% HP). Fired the bike up and went for a ride. AFRs appear to be normal, not the crazy swings I had first time out with EFIE. I believe this process DID clear out the fuel trims. AFRs at idle, WOT, and above 8kish adjusted during the ride. Going to let it cool off then go out again. I really want that CEL to turn off, then I will clear fuel trims, set EFIE up for a conservative 0.100 V, and take a ride to check AFRs.

At this point I kind of hope that open loop is not effected by closed loop trims (although my guess from the first ride here is that they are). The bike actually runs pig rich at WOT. Beginning of my ride today I was seeing 11.5! It was getting closer to 12.0 as the short term trims were getting learned. Fear is that if the map gets shifted with the EFIE the already rich open loop numbers will get even richer.

The plus side, however, is that if the injectors are capable of pumping enough fuel to generate an 11.5:1 AFR then it's looking good that the stock ECU can handle intake and exhaust... but don't quote me on that yet, that'll be Phase III.

Also, the O2 heater circuit is energized when the key is on... If ECU is monitoring the heater circuit when key is on but bike is off, that could be what caused it to throw the code.

 

[MrEvilpirate]

Kaw'ee- All comments advice welcome. Thanks for the reply. I took pics of the install I'll throw em up later, but for your questions:

Yes, Grey to ECU, for sure 100%.

Yes, Reduced by 250mv, just like Grom guys, that's why I started with 250.

Thing about the code is I figured it would throw the bad O2 code, not the bad heater circuit. Unless maybe it threw both if I had key to ON position with no O2 present. I grounded the diag port and read the flashes. Is there a procedure to see if there is more than one stored code? I held it grounded and the flashing kept cycling through the 1 code, #67 bad O2 heater circuit.

I did get WOT. It was 12, just like before. Mostly. Saw 11.8, 11.9 as well for the first time. I believe creep may be to stored long term trims???

Your text below:
------------------------------------------------
[[I'm getting 1.3 V at 14:1... so wtf?]]
.
because the Gray wire is not going to the ECU
-------------------------------------------------------
Not sure what this means Grey and Black both go to ECU. Some other forums say sometimes talk about a bias voltage to the O2. This is basically arbitrary voltage the ECU runs through O2 signal circuit. O2 only generates voltage when it gets warm enough. ECU monitors the voltage whenever it is on. So in the beginning O2 is cold, and ECU only sees the bias voltage it is sending. Once O2 warms up the voltage it generates gets added to the bias voltage... the ECU sees the change and uses the difference between bias and read voltage to extrapolate the 0.1 - 0.9 V narrow band swing. This is I think why I am getting voltages over 1.2V on the narrow band signal wire. I will check voltage at the O2 harness connection to main harness without O2 sensor installed to try to confirm there is bias voltage coming into play. This could be why the manual wants you to test signal voltage across the gray and black wires, not just ground and black, so you automatically cancel out the bias voltage. Also I need to do full continuity tests from O2 harness through ECU connection just to make sure... I've had loose wires on this bike before I had to chase down.

Yes, Cut the BLACK signal wire to O2...White EFIE wire to O2 side, Green EFIE wire to ECU side.

Appreciate the vote of confidence. Anyone else have ideas? Sucks I need to go to work and cannot continue to tinker with this sucker.

 

[MrEvilpirate]

Need some help boys.

Got EFIE wired up today. Sorta.

There are 4 wires to O2. (2) white which I believe are HEATER circuit, a black which is positive signal (to ECU) and a grey which I THINK is just a ground. But it is a ground that goes back to the ECU.

I intercepted the Black (positive signal wire) with EFIE and set it up so voltage that passed through it was reduce by 0.250 volts. Used multimeter to test I verified that it worked on the bench and once in the bike. I tested the positive signal wire on both sides of the device and all was good.

Fired up the bike and it threw a code. I thought maybe the modified signal was out of range. AFR was whacky. Started high almost 15 then dropped to 12-13. I adjusted the device to drop signal by 0.150 volts and went for a ride. AFRs were mixed. Giving it more throttle the AFRs seemed lower. with the throttle cracked they were 14.2-15. This behavior was similar to running without the O2. Coming off throttle idle would end up around 13 afr then creep up to 14.6ish after maybe 15 seconds. Almost like the system was fighting with itself. Maybe idle is open loop and previously learned trims were coming into play.

After the ride I pulled the code - #67 for O2 heater element. Strange. I checked resistance through the 2 white wires (running to the O2) and got 18 ohms which per manual is in spec. I checked for voltage feeding the heater circuit at the O2 harness and had battery voltage. So I'm not sure why I'm getting heater circuit code. The manual says next step is check continuity to the ECU and if that is good then get a new ecu lol. I think it must just be a fluke code because I didn't mess with ECU or harness wiring. I tapped into O2 harness only.

I was reading 1.2 - 1.35 volts on the positive O2 signal wire before modification, this was giving me AFR readings around 14.2. This is my first time playing with narrow band O2s so I don't know what kind of voltage to expect. I'm measuring positive signal to ground. This may be an important detail. The manual, when testing the O2 positive signal wire voltage, has you connect to the grey wire (the mystery maybe a ground that definitely goes back to ECU) and not just any ground. Not sure if this matters. For more understanding of the ramblings in this paragraph crack open that manual to section 3-62. It is for diagnosing O2 sensor performance. It says connect positive lead of voltmeter to BLACK (check) and negative lead to GREY (I used chassis ground). It then goes on:

(Rich) DC 0.8 V or more
(Lean) DC 0.24 V or less

I'm getting 1.3 V at 14:1... so wtf?

Maybe the negative side actually has some positive voltage that would lower my reading when measuring across the black and grey wires. In any event a 0.250 V drop considering the range of 0.8 - 0.24 may be too much.

Thoughts?

Tonight I disconnected the ECU hoping overnight all fuel trims will be forgotten. Not sure if I should zero out the EFIE and ride it until the CEL clears or just ride for a while with the 0.150 offset.

 

[MrEvilpirate]

Greg- I checked this out this morning on my way to breakfast. I had prepped (2) 1/8" thick washers in case I needed to shim the sensor. I rode to breakfast with 1/8" total shim, then rode home with 1/4" total shim. AFR was unchanged. So I think the bike really does run 12:1 at WOT. Maybe not best for power... but I'd wager Kawi set it up this way to keep temps cooler. Just my guess.

 

[MrEvilpirate]

OK I got the wideband in today. Put together a little PDF let me know if you guys can't see it for some reason. The file size limit here is 20k I've got ASCII art larger than that lol.

https://www.pdfhost.net/index.php?Action=Download&File=69942922d7e2d9518133b98e54464be6

 

[MrEvilpirate]

Here's my plug.

I like yours better.

 

[MrEvilpirate]

Yes Greg agree... the problem is that the fuel trims flashed to stock ECU are set too lean so with EFIE and O2 sensor you would end up richer across the board with the exception of WOT.

The exception to this would be if the stock ECU's "open loop" fuel trims were set dynamically... learned from 02 sensor and subject to change as the ECU learns the settings of your individual bike. I doubt this is the case and tend to believe that they are static... set from the factory and never change. This is admittedly just conjecture on my part. But it would seem that in the case of a malfunctioning O2 sensor they would want a static baseline to fall back on to prevent damage.