Hello everyone
If I leave the default Injection Angle Control (Start at ignition angle), do I understand correctly, that we start injecting fuel simultaneously with a spark?
So basically if I’m running port injected engine, I’ll be spraying the closed intake valve?
There’s a table under Fueling called “Injection Angle” which you need to populate with the angles after TDC on the compression stroke that you want your injection to commence. I use “End of Inection” rather than “Start of Injection”, but it’s the same process. Photo attached for an example (this car has VTEC, so the angles are a bit wierd).
Are you sure those angles are ATDC, not BTDC?
The manual says:
Injectors phase configuration window connects fuel injection start with Ignition Events. Injections
starts N degrees before Top Dead Centre of cylinder connected with Ignition Event, to which the
injector is assigned.
Also, is your engine direct injected on port injected? Mine is port injected, so I assume I should inject during intake stroke rather than compression stroke when valves are closed, am I correct?
I don’t believe you can enter negative numbers into that table, so you need to calulate back from 720 degrees (which would be TDC on your compression stroke) to where you want your injection to start. If your intake valve opens about 390 degrees before that 720 TDC, and if you wanted the injection to start at the time the valve begins to open, you’d enter 720-390=330 degrees into your table. At higher rpms where your injection pulse width is a lot longer duration, you will want to start your injection much earlier. I like end of injection because I don’t have to calculate pulse width/engine speed, just allow for intake port length and air velocity (I’m using port injection, too).
I see. But back to my original question - there is the “Start of injection (table)”, “End of injection (table)” and the “Start at ignition angle” - the last one is the default and apparently does not use the table at all, so I guess it starts injecting at TDC?
I just wanted to make sure I get it right, because its a very odd setting to be the default one, and also I’m surprised that my motor actually runs pretty okay on it.
You’re right, i was thinking of the “start of injection (table)” optiion. I never tried that other option. Maybe someone else will chime in, but thinking about it, it would start the injection about 90 degrees after the intake valve closes, which is probably a reasonable compromise point and good for mid to high rpm. You may get a smoother idle with a different setting, but if it’s running fine as is, don’t mess with it.
Hmm I guess that thats for direct injection, but for port injection i may start injecting even slightly before intake port opens?
Probably needs someone more knowledgeable than me to comment, i really haven’t thought through it.
Well, thank you for your input anyway, it cleared out the picture a bit.
When trying to grasp topics like ATDC, BTDC, ignition event, trigger tooth + trigger angle (why have separate settings?), non-direct references to angle values like “N degrees before Top Dead Centre of cylinder connected with Ignition Event, to which the injector is assigned” its easy to get lost, like, which angle exactly are we talking about…
Yes, some of the descriptions for the v1 classic take a bit of head-scratching to figure out. I just switched over to the v3 Studio software and there’s a lot more information available and bigger community for problem solving.. v1 software is adequate, but v3 is more capable and has clearer descriptions and help.
The short answer to your original question is yes.
There’s a few things to keep in mind before you get too swept up in Injection Timing and Performance.
Firstly. Its a violent wild hurricane in this part of the engine. Even if you spray onto the back of the closed valve, the very high speed air squeezing past the valve at ‘low lift’ will rip that little puddle up like its being shot out of a pressure cleaner.
Secondly, remember in a warm engine that shit is already bubbling like your mamma’s kitchen kettle. The vaporisation just from the fuel preheating on the back of the valve can be beneficial in some applications.
Third, Duty Cycle. At high duty the injector is open for almost the entire engine cycle anyway. For example, If you’re running WOT and you’re out of injector at 100% DC its because you’ve got that thing pegged open to spray with everything its got right? It basically never closes. This is why we upgrade injectors; to bring the fuel delivery up and the duty down.
Getting injection timing right will usually be an answer to a poorly running cold engine or an attempt to find best performance and economy in the idle, low load, and cruise range of the map.
Hope this helps.
Mal.
Thank you for your answer! I feel that now I have a better intuition for that.
I found that the default 400 degree advance works surprisingly good for start of injection in my case (port injection). I started with 330, then 360 for it to be around the beginning of intake stroke, however the engine seemed to misbehave.. 400 all across the table is alright. After some more VE table tuning I did some basic ignition angle setting and my engine works like a charm 
