For anything you'd like to see added to Speeduino
#51466
Torslund wrote: Sun Jun 27, 2021 12:26 pm The distributor decoder is not well designed. It is also very sensitive for disturbance. If I run speedy from a tone generator it run absolutely stable. But with a perfect signal from a distributor conditioner it can squirt randomly. I did never get my other engine run well enough for street use. Could never get the fuel steady and keep AFR.
Is it the distributor trigger, or ignition noise? See if your generator works while the ignition is firing. I'm sure you can find a way to test that.
#51493
Torslund wrote: Mon Jun 28, 2021 3:03 pm Never find any on scope, can be RF.
Or that. I imagine an ignition system is capable of disturbing ground reference for everything on that ground. I'd expect a scope to be capable of showing that though. If ground (source for a MOSFET) were to go far enough negative, and the gate stayed the same relative to the undisturbed ground level, that MOSFET will turn on. Parts sensitive to a high voltage could also die because a negative ground would cause the same peak-to-peak voltage as a higher positive; I think that killed my Arduino that I tested with zero filtering components. I'm far from an expert in electronic engineering; but I'm thinking something that isolates the ground plane in some way would be a good idea. A diode would suck because voltage drop; maybe an inductor that separates the ignition ground from literally everything else would do... a low resistance inductor of course to avoid voltage drop causing a ground offset; offset wouldn't be in a harmful direction though. Would require carefully making sure nothing on the offset ground is shorted to battery ground. Just thoughts; again, I'm far from an expert here.
By JHolland
#51498
Torslund wrote: Sun Jun 27, 2021 12:26 pm The distributor decoder is not well designed. It is also very sensitive for disturbance. If I run speedy from a tone generator it run absolutely stable. But with a perfect signal from a distributor conditioner it can squirt randomly. I did never get my other engine run well enough for street use. Could never get the fuel steady and keep AFR.

Have you checked the voltage levels? some hall-effect sensors are not rail-rail outputs and the input to the micro is a Schmitt trigger, that can give very low noise immunity, all the OEM ECUs that I've worked on use a comparator with a switching level around 2.5V and hysteresis. The other issue can be with the MAX chip timing out at low RPM.
#51517
Torslund wrote: Tue Jun 29, 2021 9:47 am I change to two wheel sync and no random squirts with same hardware.
Meaning 2 separate trigger wheels and "sync on every cycle" setting turned on? If so, then maybe try a bigger cap here (circled in red) for more filtering of distributor signal. Or just keep using what you're doing now.
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By Torslund
#51525
Strange is that with same hardware no false injection. I had the false with two different trig system, one Hall and the other VR but same rpm1 input. Now the Hall is cam sync rpm2 and VR is crank rpm1 and no false injections. The sensors is on same place as earlier. I don't know but now I will try start engine two wheel sync.
#51528
Torslund wrote: Wed Jun 30, 2021 7:16 am Strange is that with same hardware no false injection. I had the false with two different trig system, one Hall and the other VR but same rpm1 input. Now the Hall is cam sync rpm2 and VR is crank rpm1 and no false injections. The sensors is on same place as earlier. I don't know but now I will try start engine two wheel sync.
Yeah, I'm going to stick with the bigger input filtering capacitor on VR1/CPS input as being your answer.
#51529
Torslund wrote: Wed Jun 30, 2021 7:16 am Strange is that with same hardware no false injection. I had the false with two different trig system, one Hall and the other VR but same rpm1 input. Now the Hall is cam sync rpm2 and VR is crank rpm1 and no false injections. The sensors is on same place as earlier. I don't know but now I will try start engine two wheel sync.
At 56 minutes in, he talks about those inputs and mentions at some point that the filtering components may not be best for every setup. https://www.youtube.com/watch?v=SuG5068 ... MS_l49yrQI
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By PSIG
#51530
@Torslund — Please move project-specific conversation to the project thread, leaving this thread for decoder-specific info. Thanks!

For others reading, the current conversation about the V12 is a fuel-only setup with a low-resolution cam-speed trigger. This is important, as solutions such as the input capacitor value can help here, but for higher-resolution triggers and timing can be problematic. Increased tooth count and input speeds with a higher-value input capacitor can lead to ignition timing drift or rpm limitations, due to how the cap affects the signal.

Again, I am stating this only to make it clear to other readers that this possible solution is specific to this project and its properties, so users don't randomly change cap values on their inputs for other purposes. There is a method to the madness. :lol:
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