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Non ECU Motorcycle erratic reading

posted Sep 10, 2016 23:16:57 by dukeswift
Hello all! This kit is amazing, and I'm installing it on a '96 Ninja 250 I'm planning on racing next year. Now, I know a lot of people said this couldn't be done on a non ECU motorcycle... BUT, I figured if TrailTech could do it, why not the awesome Arduino?

I used a wire I had laying around that went on a TrailTech Vapor (~20 gauge) and wrapped it around my spark plug wire about 12-15 times. I hooked the tachometer positive to a 12v source, in this case the positive wire going into my coil and the negatives to negatives on the bike (still not sure if both wires can go to the same negative?) Since the video I figured out how to segment the LED's but the issue is still the same. I'm getting erratic readings at idle, but as soon as I accelerate it clears up and runs like normal. Also, it's taking FOREVER to change some of the settings. I have to keep scrolling and scrolling to get any change. Before installation, I tested the positive to a multimeter and was reading around 13 volts at idle, when accelerating it drops a bit. Could this be the issue? I feel like it needs a little resistance from coil>wire>Arduino.

You can see the tach reading on the digital display, which seems fairly accurate!

Also, my electrical experience is a little limited, and second my soldering skills aren't the best but double checked everything while assembling. Thanks!

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[Last edited Sep 10, 2016 23:18:12]
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13 replies
dukeswift said Sep 13, 2016 19:08:09
After lots of research last night, I think I might have found a solution! Apparently in the kart racing world they make inductive pickups that filter spark plug signal. I've seen a YouTube video of a guy who made his own for an Arduino tach, but figured I'd give one of these a try!
dukeswift said Sep 20, 2016 00:37:03
So with everything hooked up I can get a decent signal rolling on the throttle to max rpm, but the idle signal is jumbled and all over the place. Setting the PPR to about .6 seemed help a lot but the problem still remains. Anybody out there with any solutions? I've tried making my own filter, and the MSD one listed above but the problem is the same.
Jonduino said Sep 23, 2016 13:07:01
Hi Hunter,

This is the inductive clamp I'm currently playing with.

I also experienced this jumpyness when I tried it on my vehicle - the only thing I can think of is signal noise. I would try putting a 10k resistor in-line with your DIY inductive coil, and then also putting a 10k resistor from the coil to ground and see if that helps at all. Or try one or the other. You can also try to add a small ceramic capacitor and test that affect as well.

Sorry there isn't a whole lot of development yet on this front, it's sort of uncharted waters right now.

- jon
dukeswift said Sep 24, 2016 19:00:46
So we've built a circuit to clean up the signal and tested it on a friend's bike. First we tested the Arduino to make sure it was functioning properly off his ECU, which it was. Then we tested wrapping wire around the spark plug wire and that worked fine as well. Jump forward a few days and all I've done is make better wire connections and cut the PCB to a smaller, more compact size. Now the issue is the filter won't register to the Arduino unless I touch the board with my fingertips. Touching = works... as soon as I let go no more signal. Not sure what this could be, BUT WE'RE ALMOST THERE!! Anyone have any suggestions? Here are photos of what we built along with the forum where we got the idea.
[Last edited Sep 24, 2016 19:01:51]
Jonduino said Sep 25, 2016 00:40:55
Fantastic work!!! This is huge!! I'm going to read and re-read this more, but in the meantime, I think I know your issue with the touching.. Did you leave pin 4 on the 555 floating? Connect it to VCC and see what happens.

See this post:
NeedTach said Oct 06, 2016 23:35:42
Any updates on this? did connecting pin 4 to VCC help?

Would you be willing to share component values you are using?


Ian said Apr 17, 2017 09:51:32
Could tbe op follow up with a conclusion in this and the final values and circuit used, would really appreciate it as I'd like to get mine working too?

dukeswift said Apr 18, 2017 01:44:03
Sorry for the late response, I've been doing lots of mechanical upgrades to the bike and since the tach isn't a necessity I put it on the back burner. I'm ready to test the components again within this month and will post the results here as soon as I get any more info.
dukeswift said Apr 23, 2017 02:58:58
So update, got the new kit hooked up, with some adjustment it's still having​ some issues with the signal. As you can see in my video the signal only works when I pinch the connection on the tach wire from our filter to the Arduino. My friend says we need an extra capacitor either in line or on our filter system. Any ideas?
dukeswift said Oct 26, 2017 19:06:03
Okay so another update follows...

We have successfully attached a neon bulb to the spark plug wire, and subsequently grounded one leg. The bulb flashes, so now all that's needed is an optic of some sort to give the Arduino a steady, clean signal. This should be the easier route, compared to what we were trying to achieve before. Will update this in a few weeks after we get some testing and draft up some design for a container to keep the filter inside of.

Thank you for your patience you all!!!
Jack Smith said Oct 27, 2017 08:40:42
It works well with no ECU, I am using on my motorcycle no ECU
[Last edited Oct 27, 2017 08:41:20]
dukeswift said Nov 21, 2017 18:02:42
Douglas, I've purchased two of those and still can't get a clean signal from it. At this point, I'm honestly considering converting my race bike to EFI/ECU setup for tuning purposes. I still have an MSD converter lying around, I might give it another go this winter sometime.

Jack Smith, if you could provide photos of how you hooked it up I'd be delighted!!!
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