139QMB EFI Conversion - part two

[theswede]

As some of you probably remember, about seven months ago I began a project to convert my china-scoot to EFI using the Ecotrons kit (thread here: scooterrebels.proboards.com/index.cgi?board=50ccscooters&action=display&thread=1476 ).

I had a number of issues with the kit, mainly that cold start was horrible and I also had pretty severe overall power loss.
After being stranded multiple times I basically got fed up with the project and bought a Yamaha C3 to get around. Since then the old china-scoot has been sitting in my garage, waiting for me to work up the inspiration to fix it.
The last thing that happened before I gave up was that Matt at Ecotrons sent me a new fuel pressure regulator, and a new pump as indications seemed to be pointing at low fuel pressure as a possible culprit.

Well, since my C3 is down with a bad rectifier and the weather is absolutely horrible I figured I needed something to do and that I might as well install the new pressure regulator today.
And lo and behold, replacing the damned thing seem to have fixed my issues!

I reset the fuel enrichment factor (VAL_fFlApp) to 1.0 (I had previously been forced to have it at 1.4 to make the engine run), bleed the air out of the system and after some cranking the scooter started right up.
Compared to previous tests with VAL_fFlApp at 1.0 I now have what appears to be a full range, rapid throttle response.
The weather is too bad for any trial runs, but this looks pretty promising...

Being curious I pulled the old regulator apart and found that an o-ring had jammed sideways in it and quite effectively stopping the regulator function completely.
Below is some pictures:

Regulator


Jammed O-ring


All parts in order of assembly



The regulator is Made in China of course, and it seems the guy assembling it had a bad day...
One way of testing this regulator is to put the inlet pipe to your mouth and try blowing thru it. It should be impossible (unless you have lungs that can work up 2.5 bars worth of pressure ). The malfunctioning regulator I pulled from my scoot was wide open, it was as if I was blowing thru a tube when I did this. After putting the o-ring in place and re-assembling, the regulator now works as it should .

It seems I am back on track, and as soon as the weather settles down I'll be making some trial runs. ;D
Will keep you posted!

[Rebel]

Great, glad to see you are working on this again. Seeing what you get put of it will be settling a lot of anxiety about doing the conversion for some people.

[jmkjr72]

so the fpr is kinda servicable
when i was tinkering with the zuma the other day i noticed the orin for the injecter has already gone to crap
(i didnt think to swap out the orings i did use my own fuel line for the swap)
so i will end up replacing the orings for the injecters and the fpr with fuel safe orings
looks like there is 2 orings in the fpr the small black one and the larger blue one

[Enviromoto]

How do you control the fuel?

[jmkjr72]

you acess the ecu thru a serial port and can adjust the map thru a program

[theswede]

I went out for a test ride as the weather has cleared up and it does indeed seem that half of my problems are gone.
The scoot starts easily and idles well, cold or warm so those issues seem to be gone.
However, I am still not seeing the same performance as I had before the conversion with a 20mm CV carb. Top speed is only about 55kmh, before I was able to push it up to 67kmh...
I did log the entire run to my laptop, and have sent the logs to Ecotrons for analysis. Hope to hear back from them soon with some suggestions what can be done to improve WOT performance.

The logs also show that the battery voltage never goes higher than 12.5V, so I will need to do something about the charging circuit too eventually.

[Enviromoto]

Dec 30, 2011 7:31:57 GMT -5 jmkjr72 said:

you acess the ecu thru a serial port and can adjust the map thru a program

Thats pretty sweet, but it seems like it would be difficult to tune without a dyno.

[jmkjr72]

well like thesweded said you can send the logs to matt and he can give you an idea of where to tweak based on the logs from the sensors or you can just have at it

i have yet to hook up my o2 sensor and when i do that matt said the system will work on a self learning set up

but i didnt realy ahve to worry as i was a bit on the rich side with my set up and im willing to bet when i get the more cc in there i will be spot on

plus there are larger and smaller injecters

theswede im in the same boat as needing more juice on the charging circut side with mine too i will more then likely be sending my stator in to have it rewound to put out more juice

[Enviromoto]

Thanks for the info

[theswede]

I heard back from Matt regarding the data logs, he made a few suggestions which I will try out to improve WOT performance.
First of all I need to check my CVT and clutch setup, the logs show rpm at about 9000 when I am doing 55kmh, suggesting I either have the wrong variator weights or a slipping clutch.
I will also test running in RICH mode (lambda 0.85), that will provide more power than ECONOMY mode.

I am somewhat confused about the high RPM, pointing at possible CVT and clutch issues; nothing has changed in there since the conversion, and I have only ridden about 20-25 miles or so since.
If there is no slippage (and I don't think there is), it seems that the HP and torque curves are dramatically different from before and that this is somehow causing the behavior I am now seeing.
I will begin with drawing a couple of marker lines on the front CVT pulley to find out if I am using the entire range of the CVT.
I dug out some old figures for speed and RPM, before the conversion:

Idle: ~2000
Takeoff with WOT from standstill: 8300-8400, drops to about 6500 after a few seconds
WOT, 63kmh ,no wind: 6500-6700
WOT, 54kmh, high headwinds: 6500
2/3 throttle, ~50Kmh: 6500-6700
WOT, 70kmh (max speed ever seen): ~7000

A dyno would be really helpful at this point...

jmkjr72, rewinding the stator could be a possible alternative. I'd be interested to learn more if you decide to try it.
For my part, the first thing I will try is to beef up the gauge of the wiring between the stator, the rectifier and the battery. The wires are awfully thin with almost no copper core so there could be quite voltage drop simply because of this. Should be fairly easy to do, just slap on some more wires in parallel to the existing ones.
Next step would probably be to replace the rectifier with a 100W Nakaru (or similar) unit.

[jmkjr72]

well my problem with the zuma is i only have 1.2 amps going to the charge circut and with the fuel pump and ecu on the charge circut it sucks it all up
i still think that if a do a full dc conversion i will be borderline maybe send it off and have them rewind it and set it up for full dc if they think that is the only way ill get the juice i need

yeah if you are hitting 9000 and not going any faster then you were at 7000 rpm then something is wrong in the trans

[theswede]

I took a longer ride today (35km) to test some more, and indeed there was a difference between running in RICH vs ECHO. Not a huge difference, but still.
Also, it seems the EFI needed some more time to self-tune, performance improved during the ride.
Engine temp (oil) never got above 90C which is comforting (outside temp was 7C).
However, I am still hitting very high RPMs after long time at WOT so I need to tear down the CVT and check it. I am thinking I may need to replace the torque driver and possibly the clutch, they are original and have some 4000km's on them.
Anyway, the EFI system seems to be working as it should now! ;D

It's been a long ride to get to this point for me, but I would still definitely recommend the kit for anyone wanting to convert their scooter to EFI.
I would not say it is something for a beginner, but more for the intermediate rider/mechanic.
Ecotrons provides excellent and rapid support, they really want to help their customers.
I'd hesitate to recommend it for a 50cc though; the electrical power consumption is probably too high to be sustainable in the long run. A 150cc with an 11-pole stator seems a good starting point.

And if anyone finds a place that sells 11-pole stators for the 50cc 139QMB, let me know!

Cheers,

Otto

[mainepeace]

Hey, glad you're getting the EFI kit working! I haven't been by in a while so I'm not sure what your issues were. I haven't had a chance to read the other 5 pages yet.

Anyway, my kit is working perfectly, except for an intermittent issue with the connection to the oxygen sensor. Not a big deal, just haven't tracked down the loose wire yet. It still works great in open loop. Just a bit more power in closed loop.

11 pole stators to exist that work, but you need to convert to a DC electrical system. I haven't bothered to do that. I have solved the power draw issue with putting in LED tail lights and a larger battery. I also hook it up to the Battery Tender, Jr. occasionally. My average commute is 2.5 miles each way, definitely not enough to charge the battery. Anyway, email me if you have any questions as for some reason I don't get notified for PM's.

Greg

[theswede]

Thanks Greg!
In short, the issue was the fuel regulator. Not enough fuel pressure = EFI issues. New regulator solved the problem.
I have not been able to ride since I rebuilt my CVT, except for a few trial runs to check that the CVT is working properly. The winter weather finally arrived in force here, an I don't like to ride on ice and snow.

I did replace my battery, managed to cram a 12Ah one in so I should be set. Tail light is LED already. And I have a battery charger that doubles as a battery tender so this is covered.

Otto

[jmkjr72]

well as soon as the rest of my parts get in and it warms up some i will be able to test how the efi set up reponds to upgrades on the 2 stroke
plus it looks like some of the euro spec yamahas 2004 and newer run a 12 pole stator so i have a used one on the way along with the fly wheel to check that out

but i did find while doing work that i should have upgraded the orings not just the fuel lines as the orings on the injecters have rotted out already