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Help with building your Speeduino, installing it, getting it to run etc.
By kettlekev
Thanks PSIG, yes some experimenting to do.

The main question was about the igniter handling the 0.5 ohm coils given that Ohms Law would suggest it wont (8.5 amp rating) but also knowing it isnt that simple!!

I am happy Speeduino can drive the igniter but has anyone used that igniter (Bosch 211) with low Ohm coils?
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I think you're missing some concepts of possibility. Low-ohm does not automatically mean high-amp. More commonly, it means equivalent amps but less time to get there. The coil field builds with increasing current (amps) across the dwell period, and a low-ohm coil would simply dwell for a shorter period.

Your 3-ohm coil may only be flowing 1 amp after 1ms due to induction, so the 8.5A limitation is not applying at that point, and probably never. Likewise, a 0.5-ohm coil may see 6 amps maximum, but reach that level quicker than a 1-ohm coil of otherwise similar spec's. The electromagnetic field building quicker means full-power sparks at higher rpm (if needed), or better spark energy if speed would limit dwell time, such as single-coil V8 distributor setups, etc.

So, answering your question from a different perspective, I've used 211 or J121 drivers for almost all the coils I've used. Not that other drivers wouldn't work as well, but those are cheap and handy for me. No problem with any of them, although tiny coils actually requiring high-amps would be an exception. There are driver alternatives for those cases, including the DIY versions using IGBTs found on these forums or something simple you assemble yourself. ;) Speeduino is equipped to drive any of them (TC4424), and can even drive CDI amplifiers, making the options nearly limitless.
Last edited by PSIG on Mon Feb 22, 2021 8:08 pm, edited 1 time in total.
By kettlekev
Thanks PSIG, I knew Ohms law wouldn't really apply due to induction and just wanted to make sure I wasn't missing something.

I spoke to the guys at Dynatek and I'm looking at the DC3 coils. The techs there reference an 8ms dwell time but from the previous post comments I will start at 3ms and see what the dyno gives me.
DC3.PNG (45.32 KiB) Viewed 512 times
I've bought a thermo couple to monitor coil temperature as well just for fun.

New high compression heads back next week and new coils on the way so will post again later.
By kettlekev
Summary of getting to the bottom of the noise/sync loss so far.

Suppressed leads (carbon/silicone) and plug caps help.
Shielded trigger wires help
Location of the ECU doesn't help much which was kinda the final clue really as the majority of the issue seems to still be noise on the power lines (12v in).

I bought a couple of the ferrite noise reducing cores. The biggest improvement was putting it on the 0v but having one on the +v as well also helps. NOTE: you need to have as many coils of wire as possible through the core.

I have resistance checked all the earth points and they are are all pretty close.

Its OK now up to about 5.5k then it will start dropping out (sync loss) again.

I tried a radio noise suppression capacitor (2.2 micro farad) but that didn't help much.

I think I need an AM radio and a scope again now to see what the major remaining component is, radio frequency or just on the power lines.

If its still power lines then all I have left as ideas is capacitors on the + 12v. unless anyone has any other ideas?
By kettlekev
Does anyone know if all spare inputs on the arduino have the pull-ups enabled in the code?

I am making improvements with the noise/sync loss but it still drops out at high revs.

I have resistor grounded the CLT and IAT inputs to stop them floating but just wondered about the spares?
Just read back through, and you never really clarified if you had resistor type spark plugs, just that plugs are ok! If you don't have resistor type plugs then you will have issues. A wide gap can also cause issues, so perhaps check, and close them marginally, to see if that resolves the sync loss. If it's a miss fire causing the sync loss, then check you haven't reduced the dwell compensation % to much as the voltage rises.

Perhaps post your tune.

In the latest FW, that dropped yesterday, there is the option to vary the dwell over rpm.

If you intend to install the new FW, then can I suggest you create a new project in TS, and that will enable you to more easily revert if you feel the need. :)
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By Chris Wolfson
Here is a link to the 2009 Bosch Motorsports catalog. In this old edition you still find some parts that fit Speeduino and other aftermarket ECU like MS better than the newer, far more expensive stuff listed in the newer catalog version.

You can pick the data for the ignition coils directly from the data sheet and find correct dwell values without guessing.
Many "motorsport" parts have been widely used in production cars.

https://www.bosch-motorsport.com/media/ ... g_2009.pdf

Downloading on your hard drive is a good idea, as Bosch often deletes older data sheets and valuable information without notice.
By kettlekev
Thanks guys

To clarify;
Resistor plugs
Resistor caps
Silicone/carbon leads
I tried twisted pair power cables and screen power cables which did improve things
Speedy is in a EMI protected box
Unused inputs (I am using Alpha N system) like CLT and IAT are resistor grounded
wired to and from bosch trigger are screened
New coils work very well (other than increasing sync loss at high revs)
Crank trigger signal log is clean
I also tried inductance (rf) coils on the power lines and that helped at low revs but not high

If there are any other floating inputs that dont have the resistive pullups assigned or a sensor input I should be grounding that I dont know about, then thats all I can think of at the moment.

Its definitely not just a misfire. Sometimes all 3 cylinders momentarily drop out.

I have one more thing to try today and will post tune/results to night.....
Check all the settings in TS. Make no assumptions.

Turn off engine protection in case its cutting in early because its a 2 stroke.

Check launch control is turned off.

Is the usb connection sound, as that can cause speedy to keep restarting.

I've forgotten what trigger set up you have, but is the sensor set up correctly. is the gap ok, is it directional.
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