Scheduling of primary pulsewidth and timing calculations

[GartnerProspect]

For the record, I'm not following much if any of this!

But I love pretending!

These are things I need to get my feet wet with. I have a lot of questions but I'm going to wait until I have a firmer grasp on the whole thing before I waste anybodies time.

Thanks for the project, it's exactly what I've needed!

[Fred]

This thread should go some way to explaining why we don't want a separate CPU for wheel and calc etc as mentioned in another thread I posted in earlier.

Thanks for the project, it's exactly what I've needed!

No problems, I hope it grows to exceed all of our expectations :-)

[AbeFM]

yeah - the closest I could see for that is counters to handle lower priority things. I wouldn't want to poll the counters, since that leaves some ambiguity. But you could get reasonably accurate rates by setting a counter to count a specific number of pulses, have it reset on the next pulse, and interrupt when it hits it's target number of counts.

[Brian]

Ideally what we want is the following :

Ignition timing :
calculation just before dwell begins to optimise dwell length for potential spark angle range
calculation done again while dwelling to further optimise spark angle with the latest data (mainly relative to where the crank currently is incase the rate of rotation has changed, but potentially to get a new spark advance for new environmental variables.

Fuel pulsewidth and to a MUCH lesser extent timing :
calculation just before starting the pulse such that intended length is close to accurate and start time reflects the most likely range of end times.
calculation again while the pulse is flowing as close as possible to the end to enhance the length of time that it is open relative to current environmental conditions.

Fred, with sequential injection, I am wondering how you are going to do it, are you planning to specify the start of injection point or end of injection point? Are you thinking of having a fuel map for each cylinder, or an offset table for each cyl, or fuel trim per cyl, or single fuel table to start with?

What are your thoughts on injecting on a closed inlet valve, until it becomes impractical as the PW is too long?

Brian.

[Fred]

Fred, with sequential injection, I am wondering how you are going to do it, are you planning to specify the start of injection point or end of injection point? Are you thinking of having a fuel map for each cylinder, or an offset table for each cyl, or fuel trim per cyl, or single fuel table to start with?

Currently the plan is user specifiable start OR end OR middle. The other aspect of the plan is one main fuel value derived from one or more maps/algorithms and a single trim figure per cylinder. That could be moved out to a 2d table each or even a small 3d table each in future though if there is any point. You could even write custom firmware to have a table per injector in a v twin application like yours. I'm trying to keep it modular so that different needs can be met with minimal changes to other aspects. Time will tell if I'm successful or not.

What are your thoughts on injecting on a closed inlet valve, until it becomes impractical as the PW is too long?

Jumbled and ill-considered. Oh, you meant what exactly, ok :-)

Considering the valve is closed more than half the time anyway, that probably makes sense. It could very well entirely depend on the physical design of the engine in question though. I saw that SAE video, but I *was* thinking that you are better off keeping wall wetting minimal by planning to end shortly before the valve closes and starting whenever you need to to achieve that.

What I do know is that various engines have a strong preference for different timings at idle particularly. It will be interesting to see how the behaviour correlates with known timings. I'm sure some experienced tuners out there will already know all the answers to this. Perhaps check out the VEMS documentation if you can find it, they may have some info on that.

Provided the system is suitably flexible we will be OK anyway.

Fred.

[AbeFM]

It would be fun to have an injector phase control (with a nice friendly GUI and a big dial!) to play with!

[Delta]

like this?

[AbeFM]

I guess I should have asked for bags of money, instead.

The biggest complaint is that red text in the bottom right corner....

But more or sell, yeah - include a phase adjust and it'd be pretty much what I meant. Of course, I'd want to put my cam profile into the red and green lines.

[Brian]

What are your thoughts on injecting on a closed inlet valve, until it becomes impractical as the PW is too long?

The Buell ecu attempts to always squirt fuel on a closed inlet valve, in that the end of injection point is just before the inlet valve opens. I don't know why, I can only guess.

With software like Delta's (WOW Delta!!!) it will be possible to find the best inj timing scheme for a particular engine, depending on what results the owner is tuning towards (economy/emissions/performance). Using software like that is going to be extremely educational (for me at least).

[Delta]

I guess I should have asked for bags of money, instead.

The biggest complaint is that red text in the bottom right corner....

But more or sell, yeah - include a phase adjust and it'd be pretty much what I meant. Of course, I'd want to put my cam profile into the red and green lines.

Notice it has valve events (cam timing) in the bottom right, which change the green and red lines. That table is to adjust the injector phase (blue line). So its exactly what you want.....not a massively expensive ecu either its my EMS8860 - and yes I just opened the software without attaching it to the car.