Made a drawing for the valvetiming according te bart and Ken... (as far as I understand it)..

Looking at it, it seems the inletvalves open about 360 degrees befor TDC (which is again TDC )




A normal rule is to squirt all the petrol befor the inletvalve opens (Take a look at the Megasquirt picture above)..


So I can make a very "simple" calculation....


I know the pickup sits at 45 degrees befor TDC.. So I can calculate te opening and closing time of the injector of the next crankshaft revolution...

So lets say the engine runs at 1200 rpm... and lets assume the injector needs to be open for about 6 milli seconds (0.006 seconds) yes this is a real number. (at least at my car running at lpg..

Here we go..

running at 1200 rpm each revelution takes 60/1200=0.05 seconds or talking in us (1 us = 0.000001 seconds) this is 50000us

so 1 revolution takes 50000us.
the injector is open for 6000us..

45 degrees = 360/45 = 8

so from pickup to TDC = 6250us

so from pickup to TDC in the next revolution it takes 50000+6250= 56250us

So if we want to squirt all the petrol befor the opening of the inletvalve the inletvalve starts to open after 50250us...

Hope you understand...

So we can do this in some variations..

end the injection time before the valve opens
start the injection time when the valve opens

You can even make a table that when rpm increases the petrol needs to be injected earlier (do to the drag)..

Hope you all understand once again what I'm trying to say....

There is quite much of thinking, when timing squirting. My opinion, there isn't much benefits, only make the system more complicated than without timing. Also, when rising RPM, the time when to squirt, became very short, too short to squirt fuel when inlet valve is open...

http://www.megamanual.com/v22manual/mfuel.htm#batch
Something more about sequential and timing squirting...

I asked earlier, what are you looking with sequential system..?


And about understanding, I'm quite sure not many can understand, including me. It's not you, it is the whole issue under sequential, and with many, about fuel injecting also...

First... I need a timing. I need to know how long the injector needs to squirt.. to squirt the right amount of petrol

So I need to know at least:

RPM*
INLETMANIFOLD pressure*
COLANT temp (in our case the temp in the heatexanger)*
Airtemp**

* I'm doing this already with 1-2-spark...
** I'm doing the Coolant temp already so I can copy that..

I will make a table just like the ignition-advance in 1-2-spark where I can put in the time the injector needs to squirt related to RPM and MAP this is called speeddensity..



So for a start I don't do sequential at the moment (megasquirt) and I will not either 1-2-Squirt for a start..

Sequential means you only squirt petrol to the cilinder which is at the intake stroke...

(For a start) I'm going to squirt semi sequential, I squirt to both cilinders simoultanlesly half the amount which is needed so theres also a squirt in the exhaust stroke...

At the (very) end I'm looking for sequential injection to get more fueleffiency... I have 4 injectors at the moment so I guess they will go all the way (staged injection) doing sequential injection...

Are you squirting into the manifold or into the head, you mentioned a BMW throttle body @ one point? I remember a diesel Transit Mk1 years ago that had a single injector in a manifold rather than 4 in the head, as the later ones, God it was slow...

Hmm. Sequential mean right that, but semi-sequential means that you have for example two banks in 4- or more cylinder engine, where in four cyl example two injectors squirts simultaneusly. At this, when squirting to both cylinders simultaneusly but two times per round, isn't semi-sequential...

First semi-sequential, as far as I know, was in Bosch D-Jetronic. That has two banks and timed injection, based on two triggers on distributor...


Maybe we are talking about different issues with wrong terms, me, you, others? Still I think, in yours plan, there is nothing about semi-sequential. Please advice me, if I'm totally wrong...

Here is my opinion (maybee I give it the wrong name) but this is what I mean...


Sequential.. 1 squirt per 720 degrees..
timed sequential.. 1 squirt per 720 degrees. starting at a certain degree or ending at a certain degree

semi sequential.. 1 squirt per 360 degrees (so there will be also a squirt in the exhaust stroke)...
timed semi sequential 1 squirt per 360 degrees. starting at a certain degree or ending at a certain degree

Bank fired.. at least 2 injectors firing alternating 180 degrees (2 banks of 2 cilinders) so you can make semi sequential with a 4 cilinder.....
or at least 4 cilinders firing alternating 90 degrees at a 8 cilinder aso.

Batch fired all the injectors (minimum 1) fire at once (so at a 4 cilinder they squirt 2 times per 360 degree)

untimed injection... Making as many squirts as your engine runs best....


Again, above this is how I see it, this can be diffrent from reality....

Yes, it is very different from what is talked everywhere else, when talking about sequential. Why don't you just talk "same language", it is very confusing when you use totally different terms...

Please read the link about sequential injection part from Megamanual, and after that, think again the terms what is used and compare them to yours. The terminology isn't inspired by these Megasquirt developers, same terminology is used also with Bosch etc...


The reason why I recommend to use same terminology, it helps all of us to talk about...

Now I'm very sure I've got it right about sequential injection...

Now please do explain how you think about it..

In sequential injection, there is a squirting sequence, as is with ignition. In semi-sequential, there isn't controlling of all injectors separately.

That isn't relevant to sequential injection how many times injectors squirt/engine cycle. They can be squirted one, two or more times per engine cycle, and it is a different issue than sequential.

How do you explain why for example in Megasquirt you can alter how many squirts/engine cycle is, with simultaneous, alternating, semi-sequential and full sequential injection..?


Or are we still talking different issues..?

Geo, take a look of this also:

http://www.jbperf.com/sequential/index.html