[Old Grey]

The timing is what I thought, but I didn't think about starting 500º before IVO

Weird we didn't hear from the boss if Individual cyl timing is possible

[PSIG]

Where it ends is the critical spec, as it must end well before the valve closes, else some is left behind. At short pulse widths, the entire shot is captured during valve open, ending while fuel can still make it's way in. As PW increases, the start angle increases, firing fuel onto the closed valve before it opens—rather than extending to after it closes. If the required PW is long enough, it can literally go 100% open across all strokes, cycle after cycle if necessary in most systems.

David

[Old Grey]

Yeah, I kind-of assumed that fuel is only added when the air column is moving, or what's the point of sequential, but I guess you can fudge a smaller injector by starting it earlier. Basically I was assuming that if you only use the IVO period you would need a bigger injector than something that squirted twice per cycle, ie once per rev.

[Old Grey]

A little behind schedule this months Speeduino firmware, but the exciting news is that the just released October code drop now includes full sequential fuel and ignition control!

Looks like we got our answer, lucky because I was about to I cut my 4 IGN channels.

[noisymime]

Yeah, I didn't want to ruin the surprise too much

The idea of sequential only injecting on an open valve is great, but beyond a (fairly low) rpm/load level it's simply not possible because the valve just doesn't stay open long enough to get all the fuel in.
Speeduinos timing is all based on the end angle of the squirt rather than the start. I'm sure an argument for specifying start angle could be made, but by far the most common scenario is that you want to specify the end angle and so that's what I've targeted.

[usatracy]

it would be good because we can address issues of heat in our ultralight plane engines where one cylinder always runs hotter so either, you run less power, or you bite the bullet cause you need that take off climb power and your engine needs rebuild sooner cause you cant control the temp of that one cylinder, issue for 30 years with no solution, sometimes dual carb can help, richer

[PSIG]

it would be good because we can address issues of heat in our ultralight plane engines where one cylinder always runs hotter …

This is the point of sequential - per-cylinder control. To allow one injector to control fueling to one cylinder, and timing for that one cylinder. The fact it is physically "sequential" is not magic, relative to the access to per-cylinder control. This allows control such as per-cylinder fuel volume, ignition timing, fuel timing, and other advantages to some clustered systems, if the tuner can actually apply it.

To use an example, race teams with very advanced systems are not after the sequential for "sequential", but to enable the fine adjustment of per-cylinder performance, and to prevent the engine capability to be limited by one cylinder, due to forcing all cylinders to use the same fuel or timing as that limiting cylinder. The OEMs use sequential to comply with regulations, and provide specific data for troubleshooting. Different goals, different uses.

The list goes on, but if you cannot use or effectively apply these capabilities, sequential is not a benefit to your project. Your project, your goals, your judgment.

[gcosens]

I'm interested in this feature but I can't seem to find the settings in tunerstudio. Is the per cylinder ignition timing feature still available or has it been removed as I noticed this is a bit of a thread resurrection!

[PSIG]

ICIT (individual cylinder ignition trim) has been on the radar for most of Speeduino's life, but has never been available. A bummer, as the fuel trims (ICFT) and ignition trims are an enabling (codependent) pair that are much more powerful and useful together as a team. Realistically, the percentage of users that can effectively apply ICFT and ICIT are relatively small. But, if you have sequential to access individual injector control, and the ability to access per-cylinder data, you can use the available fuel trims (ICFT) that are available.

After a needed review of additional features to choose-from, it could well be that other features would take higher priority for a larger segment of users, e.g., possibly a built-in oscilloscope and digital signal analyzer function tied directly to inputs & outputs as a module, for example.

Space is limited in the Mega chip, especially for those that are only used for setup one time, or not directly applied to running the engine. And so selection of features requires care, but it's likely worth a review of all functions Speeduino currently has, for those that can (with gained experience) be deleted or replaced for better benefit.

While it might be cool to have a Valet function; if it's a choice between running the engine better versus those that don't, or bling or glitter items like bang-bang exhaust noise function, or functions available externally or standalone, the choice becomes quickly clearer.

[JHolland]

Space is limited in the Mega chip, especially for those that are only used for setup one time, or not directly applied to running the engine. And so selection of features requires care, but it's likely worth a review of all functions Speeduino currently has, for those that can (with gained experience) be deleted or replaced for better benefit.

I have been looking at this issue for my own application, my solution to this is to move all the 'one time' setup parameters to flash memory; that includes the IAT and CTS linearization tables and injector and ignition dwell times as well as stuff like the number of cylinders. The only issue with Arduino may be reserving memory, I use Atmel Studio so it isn't a problem.