[jonbill]

Thank you for your reply.
If there's a way to get some logging to parse this, please let me know.
I'll give it a try.

In TunerStudio, data logging->start .
This won't tell us anything about the precise timing of teeth and ignition events, but will help with the context.

[JHolland]

With Speeduino you can't have an output event at the same time as a trigger event so you will always get some delay. I don't see anything in the code that would cause that amount of delay, what you are seeing is a lot of potential processing time. I suggest that you post your configuration and a log, maybe its a setup problem.

[JHolland]

@JHolland - I have seen variable input/output delays, but consistent with little jitter or scatter in most setups with little variation moving from cylinder-to-cylinder with a timing light, on ones I've checked. Timing table compensation is simple for this overall effect, as it is relative.

But are you saying C-to-C variation or per-cylinder scatter is a normal or expected effect you have seen?
Should I see this variation on the crank angle with a timing light every 720°/n-cylinders apart (as one example test)?

I agree a v2 code base using 'conventional' interrupt should be investigated as a useful improvement from a variety of perspectives. Unless of-course someone's other code, patent, or other block is preventing that, or otherwise forcing scheduling.

I have seen jitter out to around 100us, a heat map shows a curve that I would guess would be roughly similar to an exponential decay with the majority of events within something like 20us and a few outliers at 100us. You won't see it with a timing light because you won't have the persistence.
The blocker for a new code base is that someone would need to take the time to design a new board with the cam, crank, ignition and injection I/O connected to the IC and OC pins, I have been working on one for my own use but it isn't going to be a universal board.

[Shinji]

@J Holland
Thanks for your advice. Following your advice, I am attaching the two logs and configuration files I just got. It would be helpful if you could let me know if there is anything strange.
Note: These data were taken on desk to simplify the analysis, not on actual vehicle.
Shinji

[Shinji]

I have attached a photo of the actual car for reference.
The ignition system controlled by the Speeduino was a direct coil system, but since this problem was discovered, I have now reverted to the old point system.
Shinji

[jonbill]

Have you observed this problem on your actual engine, or only with your simulator?

[jonbill]

Have you tried using 'per tooth timing'? used to be called 'new ignition mode' until release 202305.
I think most dev effort on ignition has been on this for the last few years, so the earlier code path may well be old and, well, buggy.

[Shinji]

@jonbill
Thanks for your advice.

> Have you observed this problem on your actual engine, or only with your simulator?

From the conclusion, it has not been confirmed in the actual vehicle. Originally, the reason we started this test in the simulator was because we were concerned about ignition timing jitter in the actual vehicle. I thought that the cause was the signal accuracy of the crank sensor, and I was checking the speeduino's limit performance (jitter) when giving an ideal signal. I found this problem in the process.

> Have you tried using 'per tooth timing'? used to be called 'new ignition mode' until release 202305.

I tried. I found that turning 'new ignition mode' ON/OFF makes a difference. I am attaching the table of the results.
*Shift means deviation based on the ignition timing of the No.1 cylinder (=crank angle = 0 degree).
Overall, I think the results are better when it's ON, but I still think the total error of Jitter + Shift (= over 100uSec in the result) is unacceptable for the 2st engine. Is this the expected range for Speeduino specs?
Shinji

[Shinji]

For reference, I will share the data when I changed Crank Triger teeth from "6-1" to "24-2".
When NEW IGNITION MODE is turned on, the shift amount (error between cylinders) is improved, but the jitter increases a bit.
Shinji

[Shinji]

@jonbill
> I think most dev effort on ignition has been on this for the last few years, so the earlier code path may well be old and, well, buggy.

I would like to say thank you to all the developers.
I used to turn "USE NEW IGNITION MODE" ON in past versions but stopped using it for the following reasons.
It was sensitive to the crank sensor signal and it was easy to lose synchronization. And the fatal thing was that there seemed to be a bug in the dwell control.
Shinji