Injector timing

[mayor]

I thought Steve said that as well Joe.  If I remember correctly, he corrected one of my posts where I mistakenly posted that injector timing was being changed and he stated that it was Map sampling only.   

[mayor]

here's a post from Steve that explicitly states MAP only:

Cam settings in Mastertune does NOT adjust the injectors. People have made up all kinds of things as to what it does but very few have understood it properly. NO sensor is read all the time, the ECM does things one at a time just like you and I do, it just does it a whole lot faster but they still have limits. Cam setting just tells the software where the intake valve is open or closed and this effects many things within the ECM setup. The ECM knows that it cannot do things with the intake valve open so it needs to understand where that area is.

The reason we use MAP to look at it is fairly simple. When the valve opens the manifold pressure drops rapidly so you can see it and detect that point for the IVO setting. The only thing that we see is that some of the camshafts used along with the other valvetrain components end up opening at a point that is really between the adjustment points so were stuck with going to the one just before or just after opening occurs. This is why we tell you to try them both and see what works best for you.

[1FSTRK]

here's a post from Steve that explicitly states MAP only:

Cam settings in Mastertune does NOT adjust the injectors. People have made up all kinds of things as to what it does but very few have understood it properly. NO sensor is read all the time, the ECM does things one at a time just like you and I do, it just does it a whole lot faster but they still have limits. Cam setting just tells the software where the intake valve is open or closed and this effects many things within the ECM setup. The ECM knows that it cannot do things with the intake valve open so it needs to understand where that area is.

The reason we use MAP to look at it is fairly simple. When the valve opens the manifold pressure drops rapidly so you can see it and detect that point for the IVO setting. The only thing that we see is that some of the camshafts used along with the other valvetrain components end up opening at a point that is really between the adjustment points so were stuck with going to the one just before or just after opening occurs. This is why we tell you to try them both and see what works best for you.

Steve would tend to split hairs at times. When Harley did away with the cam sensors that they had on the early twin cams they started using the MAP sensor with lots of code to identify the intake stroke. He will tell you that there is no map or table that you plug the number 15 into and it will open the injector at 15 degrees and that the cam selector program does not directly tell the injector when to open, but something somewhere does.
If the map sensor poling time and/or signal strength is use anywhere in the code to affect the code that controls the injector then it does affect the injector timing.
To say it is a myth that it is important would be to say that every fuel injected motor can start to spray the injector at the same crank degrees no matter what size, shape or brand of engine and that is just not so.

[hrdtail78]

I know what Steve said, but I also understand how one thing in the ECM effects others indirectly.  So, the IVO setting effects when the sensor polls. Does it poll only once per rotation?  Once per power pulse?  Or maybe it isn't just once.  Steve has stated how it doesn't poll all the time. So, one automatically goes to once. 

Does IVO effect ignition timing?  I believe it does indirectly.   If it shifts where you idle to the left.  Indirectly you shifted the timing table also. 

J38 has some interesting control of injector timing. It isn't only changing the timing of when it starts. It will also shift when it wants it to end by shifting the whole PW.  Changes timing with coolant temp. Does things so it isn't spraying through an open valve on to the cylinder wall. Washing the cylinder wall.  Look at the hurdles that have to be overcome with direct injection.

I believe injector timing timing is very important and dynamic. It isn't as easy as putting a couple of key strokes into code. 

[mayor]

Steve would tend to split hairs at times.

have noticed that a time or two, or four or five. 

When Harley did away with the cam sensors that they had on the early twin cams they started using the MAP sensor with lots of code to identify the intake stroke. He will tell you that there is no map or table that you plug the number 15 into and it will open the injector at 15 degrees and that the cam selector program does not directly tell the injector when to open, but something somewhere does.
If the map sensor poling time and/or signal strength is use anywhere in the code to affect the code that controls the injector then it does affect the injector timing.
To say it is a myth that it is important would be to say that every fuel injected motor can start to spray the injector at the same crank degrees no matter what size, shape or brand of engine and that is just not so.

I agree.  I made the assumption based on his distinction regarding MAP that there was more to it than he was letting on.  I would assume that the ECM is determining injector timing based on when the MAP indicates a valve opening, and by changing where the MAP reading is being taken based on dialing in the MAP sampling to the cam timing events then the injector timing naturally follows.  Steve is the king is semantics though, and the mincing of words.  I have no doubt that the only thing that the TTS  cam timing adjustment does is change the sampling area, but to say that it affects nothing else would not be  a correct statement.  One that he never made, I would add. 

[FLTRI]

I would assume that the ECM is determining injector timing based on when the MAP indicates a valve opening,...

So injector timing is adjusted after a valve opening event?

Meaning the calibration is reactive to map values as applied to valve opening?

I believe fuel is sprayed against a closed intake valve and waits for it to open.
How important is precise timing of fueling events?

Just look at a carburetor. The fuel is drawn into the intake by a opening of a valve and the piston moving down in the bore. What shuts the fuel flow off when the valve closes? If the fuel stops it also must start back up, right? With velocity through the intake starting and stopping fueling with a carb is not possible.

Bob

[joe_lyons]

Variable timing vs. Engine speed to keep up b/c of injector reaction time but it is between tdc to 45° before.  But this is based on crank tooth signal that takes time to get transfered and interpreted.  He said no to it spraying on the back of a closed valve for stock setup.

[FLTRI]

...He said no to it spraying on the back of a closed valve for stock setup.

So when does the injector spray? Before or after the valve starts to open?
Bob

[hrdtail78]

Variable timing vs. Engine speed to keep up b/c of injector reaction time but it is between tdc to 45° before.  But this is based on crank tooth signal that takes time to get transfered and interpreted.  He said no to it spraying on the back of a closed valve for stock setup.

Now I am really confused.  Stock cams open at 2 degree BTDC.  He states it sprays from 45 BTDC to TDC.  How would that be not spraying on a closed vavle?

[Hilly13]

He did but it depends on how you look at it, like from a particular point of view, you moving the ivo dosnt directly alter injector firing timing, but with that info perhaps the ecm does? it would maybe not matter for a cam that opens close to stock but for a very early opener the benifit would be there, don't know though, only guessing and fishing.

[FSG]

I don't have an oscilloscope  

While I've a few Tektronix O'scopes to chose from I find the cheapie STINGRAY DUAL CHANNEL USB OSCILLOSCOPE gets used most of the time.

[hrdtail78]

The above stock cam I mentioned was the B.  The newer cams open at 12 ATDC.  Just to clarify.

[FLTRI]

From my d/a experiences with different race teams in their engine development programs...
What is critical is be sure the injector sprays BEFORE the valve opens.
Any later injector timing and torque takes a hit.
The earlier the duty cycle occurs before the valve opens the worse the mileage.
But no measurable affect on power.
Just some stuff I picked up working with a couple Motec EFI calibrators.
Bob

[1FSTRK]

I would assume that the ECM is determining injector timing based on when the MAP indicates a valve opening,...

So injector timing is adjusted after a valve opening event?

Meaning the calibration is reactive to map values as applied to valve opening?

I believe fuel is sprayed against a closed intake valve and waits for it to open.
How important is precise timing of fueling events?

Just look at a carburetor. The fuel is drawn into the intake by a opening of a valve and the piston moving down in the bore. What shuts the fuel flow off when the valve closes? If the fuel stops it also must start back up, right? With velocity through the intake starting and stopping fueling with a carb is not possible.

Bob

The quote you reference was not made by me, it was made by Mayor and edited by you, and does not state anything about when the injector actually sprays in relation to the intake valve position.

It is always amazing how things that are out of reach for adjustment or not fully understood are judged to be unimportant.

...or judged to be important. 
Bob

You then make the following post

From my d/a experiences with different race teams in their engine development programs...
What is critical is be sure the injector sprays BEFORE the valve opens.
Any later injector timing and torque takes a hit.
The earlier the duty cycle occurs before the valve opens the worse the mileage.
But no measurable affect on power.
Just some stuff I picked up working with a couple Motec EFI calibrators.
Bob

I guess it just come down to what someone deems to be important

[FLTRI]

1FSTRK:
"The quote you reference was not made by me, it was made by Mayor and edited by you, and does not state anything about when the injector actually sprays in relation to the intake valve position."
Sorry about that.
So does the system react to the map sensor and then open the injector?
Or does the system spray fuel onto the back of the valve and waits for the valve to open?
Bob

[joe_lyons]

Do remember that the specs that we are looking at is (.053") not seat to seat. just for "Potty mouth"s and giggles lets just say the way that i took it was at low rpm it fires off at tdc but at 6500 rpm it fires off 45 btdc to keep up with the electronic lag to fire the injector.    he did make sure to tell me that this is when it sees the signal from the crank teeth that has to run to the ecm be crunched and signal sent to injector.    Dont take my numbers and think of them as per cam timing but as REACTIVE to crank teeth.  It tries to fire on an open valve not closed.  Short track manifold cools the intake valve itself pretty well i would say but i dont know about fuel homogonization?  I hate this german key board.

[hrdtail78]

That makes some since. Talking to the man that I won't mention. My KPA theory is wrong.  We do want to spray in an open valve. The engine has time restraints because of valve opening time. So we spray on a closed valve about to open when it has to.  Interesting stuff for sure. 

[strokerjlk]

Do remember that the specs that we are looking at is (.053") not seat to seat. just for "Potty mouth"s and giggles lets just say the way that i took it was at low rpm it fires off at tdc but at 6500 rpm it fires off 45 btdc to keep up with the electronic lag to fire the injector.    he did make sure to tell me that this is when it sees the signal from the crank teeth that has to run to the ecm be crunched and signal sent to injector.    Dont take my numbers and think of them as per cam timing but as REACTIVE to crank teeth.  It tries to fire on an open valve not closed.  Short track manifold cools the intake valve itself pretty well i would say but i dont know about fuel homogonization?  I hate this german key board.

[Hilly13]

Makes sense that as the revs go up the firing command gets earlier to compenste for lag times but does the ecm monitor the valve with map at all or does it rely purely on the math?

[rbabos]

Makes sense that as the revs go up the firing command gets earlier to compenste for lag times but does the ecm monitor the valve with map at all or does it rely purely on the math?

I'd bet on math based on cps and rpms. Map would be too spastic.
Ron

[Hilly13]

Makes sense that as the revs go up the firing command gets earlier to compenste for lag times but does the ecm monitor the valve with map at all or does it rely purely on the math?

I'd bet on math based on cps and rpms. Map would be too spastic.
Ron

Good word for it Ron so when we do the IVO analysis that resulting number whatever it may be must get used in some way in the ecm calcs for firing the injectors or what would be the point?

[FLTRI]

must get used in some way in the ecm calcs for firing the injectors or what would be the point?

So V-Tune is used for lower KPAs.
Bob

[Hilly13]

Whatever that cam setting does it is important somehow as Steve said many times, get it done first as it is laying the foundation for the tune, anyhoo it can't hurt even if it "aint necessary".

[joe_lyons]

Good word for it Ron so when we do the IVO analysis that resulting number whatever it may be must get used in some way in the ecm calcs for firing the injectors or what would be the point?
[/quote]

For the proper time to sample the MAP so that our ecm is in line with more a true engine MAP or with what the engine is happy with.

[Hilly13]

Good word for it Ron so when we do the IVO analysis that resulting number whatever it may be must get used in some way in the ecm calcs for firing the injectors or what would be the point?

For the proper time to sample the MAP so that our ecm is in line with more a true engine MAP or with what the engine is happy with.
[/quote]

Thanks for that Joe