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Help with building your Speeduino, installing it, getting it to run etc.
By twobarboost
Hi all.

Currently fitting a b16A2 into my Honda Civic EK.

I've hooked up the oscilloscope to the 3 different trigger wheels (all VR) in the distributor...

The three wheels are;

1. TDC / Sync: 1 rising or falling edge signal per camshaft rotation (depending on polarity)
2. CYP (Cylinder position) 3 rising or falling edge signals per camshaft rotation (depending on polarity)
3. CKP (Crankshaft position) 24 "saw-tooth like pulses" per camshaft rotation.

I'm a big fan of coil on plug for many reasons... I's like to remove the coil and ignitor from the distributor, put a low profile cap on it and run 4 x K24 coils. (there are many aftermarket mounting plates available off the shelf too)

I have a bit of a hole in my knowledge regarding VR conditioner modules and whether they can handle the "sawtooth" pattern from the CKP (Crank position) sensor. Oviously i'd like to use this one as it's 24 teeth and much higher resolution than the CYP signal of 4 per camshaft rotation.

Any advice would be greatly appreciated.

Thanks in advance.


Link below is oscilloscope readings from CKP (Crank posiiton on Channel 1) and CYP Cylinder position (4 signals per camshaft revolution)

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By Chris Wolfson
From your picture: The upper saw tooth is a sine wave, just wrong time base. You need VR conditioner.
the second line is some kind of Hall signal. The usual input could be happy with it, as it reacts to a trigger level. So please watch the voltages! 5V should be fine. As the VR conditioner comes with two inputs anyway, try to process it too and watch the result in TS.

Most problems with (not only aftermarket!) ECU installation are caused by ignored or miss understood grounding.
Be sure the Hall sensor is feed and grounded with the Speeduino. There are 2-3 wire VR and 3-4 wire Hall sensors, so verify what you have, don´t speculate.

Be aware of what you need! If you have only a crank trigger, you need a missing tooth wheel. No sequential here.
If you use crank and cam signal, you have more options. You need a crank signal for calculating engine speed and crank angle, but a missing tooth (crank) or a single tooth at the cam (or from the distributor) tells the ECU where TDC at the crank is. So there is no missing tooth necessary at the crank. This way you can have sequential injection and ignition. Be sure the cam you take the trigger signal from is not adjustable (variable cam timing!).
You can also match a missing wheel crank with a single cam tooth to give the ECU the info which cylinder fires.
IMO, If you can choose, take the last option. The engine starts faster, usually the ECU waits for a signal to orientate, with a cam signal that can be two revolutions (I don´t know whether Speeduino stores the crank position on shut down, like modern production ECU systems)
As your signals come from a distributor, you have to take care, the 24 teeth are only 12 crank signals per revolution!

The second one of your signal list (the tripple) is not usefull with Speeduino, I suppose.

Hope that helps!
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Chris Wolfson wrote:
Sun Nov 22, 2020 10:54 am
…(I don´t know whether Speeduino stores the crank position on shut down, like modern production ECU systems)

The second one of your signal list (the tripple) is not usefull with Speeduino, I suppose.
No, Speeduino does not store crank position on shutdown. Yes, the CPS signal can be useful, as part of some options. With the variables of which wheels, missing teeth or not, sensor type or wiring, which type of signal conditioner and settings, etc, there are dozens of potential combinations to explore for just this one engine setup. Cranking for an extra 1 or 1.5 seconds to sync is no problem for some, and very irritating for others. To each their own for their own reasons. Thanks for highlighting the reasoning behind them. 8-)
flatblackdime wrote:
Mon Nov 23, 2020 4:08 pm
Make yourself a single tooth cam trigger and run a crank-trigger. The crux of honda motors is timing belt distortion causing inaccurate ignition timing!
This is true, and good to point that out. But it's also relative to your project and application requirements. Belt-driven timing is prone to more "jitter" and timing variation, but it's also more than adequate for thousands of DDs, track cars, and other weekend racers, that are tuned "good enough". Pushing the engine to the bleeding edge with power adders and crappy pump gas could indicate something different. The choice of what scheme to use is up to you, for your own judged reasons. The greatest value of this forum is being aware (and hopefully understanding) those reasons. Thanks for offering some.

@twobarboost - there are many Honda whips here with lots of experience that have tested many of the optional setup combinations, and I would review some of their threads for info or guidance. Either "follow the leader" and use what others successfully have on this type of Honda setup, or study for how and why each tested factor could make your decision different. Do your thing. That's a big part of what this is all about. 8-)

By flatblackdime
I couldn't agree more with PSIG on this. For most setups the timing belt driven sensors will work just fine. If it were me the big advantage of a speeduino on a honda would be running a crank-trigger.

If all you want is COP then I'd have a look at the HondaRulez COP driver, an OBD1 ecu, and HTS. Your car will start/ warmup like stock and have all the features of a stock civic. Unless you're wanting to do speeduino for fun I'd stick with the OBD1 Honda ECU, its so well developed at this point that I feel you won't gain anything by going speeduino.
By twobarboost
Thanks for the input guys...
All of these waveforms are from the 3 VR sensors inside the distributor.

There are no hall efect sensors... only VR

One is a TDC signal which occurs once per engine "cycle" i.e. 2 crank revolutions (it is a rising edge signal)
The other is a cam signal and is honda ECU specific and gives 4 signals per camshaft rotation (not useful)

The other sawtooth pattern is a 24 tooth wheel (inside the distributor) that gives 12 pulses per crankshaft rotation.

My concern was whether the 24 tooth wheel's sawtooth pattern (which doesn't have a "straight and clean" rising edge signal like the TDC signal) was usable as its sawtooth shaped and not a straight and clean rising or falling edge from O volts.

I'm aware of the potential issues with running trigger signals from a belt driven distributor but on all OBD2 hondas (like mine) ALL triggers are in the distributor and they make 100HP per litre naturally aspirated. If Honda can do it... Then why can't a Speeduino?

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