[metcap]

Just wondering has there been any effort in Speeduino to code for an ignition latency /delay thats inherent in all efi/ecu systems? If not then why is it the case since it's obviously happening in Speeduino aswell. Easy to see with a timing light and fixed ignition timing.

[jonbill]

If you have a search, there are threads confirming speeduino latency jitter is small even at high revs - i.e. ignition timing is pretty accurate.
Can you detail what you're seeing? I think its possible to configure a VR sensor so there is some timing drift. Or possibly there's a problem with your decoder.

[JHolland]

What is the issue that you are seeing? latency and jitter/scatter are two different issues. If you are suffering from latency then take a look at your hardware, particularly, as suggested above, at the cam and crank sensor inputs. Scatter is another matter and is inherent in the way that Speeduino is designed, in my experience it will look a lot less severe with a timing light so if you are seeing a lot of scatter then I would look at the trigger wheel, is it mounted centrally? are the teeth properly spaced? is the sensor mounting rigid enough?

[metcap]

I'd think however accurate/swift signal processing is within the ecu (hardware>>software >>hardware), you'd still be left with time for ignition signal to trigger the downstream hardware ie igniter, coils, spark plug. So in my case if I put a timing light to the spark plug cable I'm seeing 2-3 deg going retard bringing the speed up from 2k to 6k rpm and I'm revving to 10k normally.
I hate to say this coz I know Speeduino is a free for use but this feature is almost standard in most of the main stream standalone efi systems so I'm just wondering why it's not a major concern for integration.

[stum]

Last time I checked on my install. Timing locked at fixed 10' from idle to red line 7000rpm, was lucky to see 1' of movement. I have had issues with some trigger patterns, trigger setups or injected noise where I have seen 5'+. Im sure some other users can comment on there's. Which may help you.

[metcap]

Exactly, no one system is built perfect and you can't expect each to be the same. I'm not sure how you'd able to get anything better than 2deg retard in a real world setup. I'm seeing at least 2 degs even on bench test.

[dazq]

Exactly, no one system is built perfect and you can't expect each to be the same. I'm not sure how you'd able to get anything better than 2deg retard in a real world setup. I'm seeing at least 2 degs even on bench test.

Are you talking about the difference between your set value and the actual point seen by the timing gun?
The trigger offset value should be adjusted to zero this difference upon initial start .

[metcap]

I dun see a trigger offset value in Speeduino, besides trigger offset is a setting just to get your timing dead on at idle and spark latency/delay just gets bigger retarded the higher rpm you go.
Here's an explain by Andy Whittle https://youtu.be/H_oYAEMGZS0?si=ZxXRac_mTjfZ1yPd
You can see the setting is in uSec value and any delay at idle is compounded the higher speed we get.
At the moment I get around this by guesstimating a value and adjusting my ignition table to suit.

[jonbill]

ah, so the concept makes sense to me now, but in practice, I don't have the problem. my ignition advance is what my ignition table says (within the limits of what I can see with my timing light). Maybe my hardware is fast enough for it to not be noticeable.

[apollard]

I don't see a shift from 1000-5000 rpm with locked timing at 18* on my V8. I do see +/- 0.5 degrees, but frankly I couldn't tell you if that's speedy or the timing light. Don't discount error and delays with your measuring device, especially at high speeds. Timing lights are cheap electronics-even in the big names- and unless it certifies accuracy at a certain speed, the accuracy they state is at the most common use point- idle.