Injector Phasing Information

[SA]

Nope.  Read the first post above again.  The injector advance map has a range of -360 to +357.  To force the injector to open at exactly the Fuel Inject Tooth location, Injector Phase must equal 0.00 and The injector advance map must be 357 degrees.

SA

[FWombat]

Ah...the map doesn't work the way I thought it did.  I thought that the map was degrees offset from the Fuel Inject Tooth, and 0 on the map would force the injector to open at the Fuel Inject Tooth location.  But what you're saying is that by default (ie no Inj Advance Map or Injector Phase modificaitons) the injector will open 360 degrees out of phase with the Fuel Inject Tooth value.  

Hmm....not intuitive to me, but as long as I know how it works I can deal with it.    You'd get the same effect at -357 as +357, correct?

- Brian

[CivicSi2k]

Ok im starting to grasp it now.  One question, how can we verify when the cam sync's?  Is it before #4 reaches tdc compression on hondas?

[SA]

Ok im starting to grasp it now.  One question, how can we verify when the cam sync's?  Is it before #4 reaches tdc compression on hondas?

Check your service manual.  It should contain that information.

SA

[B951S]

OK then. A number of 357 represents no advance and -360 representing maximum advance. I'm sure this makes sense to someone

So if I were writing a CAL file for a custom set up and put in exact injector tooth locations for inejction event from TDC, I need to put 357 in all cells in the table as a base case for injecting at specified events.

After this point, once the motor is running, I would need to determing how much advance verus RPM verus load I needed in degrees and SUBTRACT these numbers from the base of 357.

[FWombat]

Wow, talk about being non- intuitive. A number of 357 representing no advance and -360 representing maximum advance. I'm sure it makes sense to someone

...

Why could the injector advance table be programmed so 0 = no advance and +ve numbers are amount of advance added

You can set it up this way if you want.  Just change your Injector Phase value to the number of crank teeth in 360 degrees of crank rotation.  This will effectively make 0 on the map give no advance.

- Brian

[FWombat]

I would be more interested in using an algorithm like specified here <http://www.diy-efi.org/efi332/equations/algorith.htm>

Done.    I've attached a spreadsheet to this post that will create an Inj Advance Map that implements the basics of that algorithm.  You can vary the ideal inject start location, as well as the last acceptable injector stop point.  

The key is to analyze your timing pattern, and determine exactly where the Fuel Tooth for each injector falls in relation to TDC of the intake stroke for that cylinder.  Once you know that, the spreadsheet will do the rest of the work.  

Crap.  Apparently we can't post attachments anymore.  PM me for the spreadsheet, I guess.  Or, if someone were willing to host it...

With only load by rpm phasing it's not hard to get your steady state phasing, but under accel condition you could double your injector on time without changing phasing so you must compensate for endless unkown accel conditions and make steady state less optimal.  If you inject your steady state to finish just before valve close for instance and then accel and inject double fuel then that fuel will not make it into the cylinder until 1 revolution too late.

Using the algorithm on that page, the injector open point is early enough that all the fuel will be injected before the intake valve closes in most situations.  The only exception is high injector duty cycle, ie simultaneous high load and high RPMs.  In high RPM situations the 1 cycle delay shouldn't be a big deal anyways.  

It's low RPM/load where the accel conditions are really critical, and in these situations there should be plenty of time for all the fuel to get in, even if the pulse width were to double.

- Brian

[BLKMGK]

Hrm, I think every CAL I've looked at has that table zeroed. Umm, is that "bad"? Reading this I have to admit I have little clue where to start or how to exactly tune this if I was looking to get it near where my valve is opening. Please tell me some thought is being given as to how this table can be simplified so that refrencing manuals and trying to calc things isn't needed as it seems to be now.

[SA]

A missing piece of information for each application is the location of the tooth reset point right?  Maybe AEM should start publishing that information in the instruction manual for each new application.  Yes?  You still need to know where your valve events happen though.  That's up to you.  

When we set up a basemap, we normally don't spend too much time tuning the advance map for the stock engine.  As soon as you modify the motor, the optimum settings will usually change.  Typically, we tune the Injector Phase option to get good throttle response and idle quality and sometimes you'll see advance maps sloping upward with engine speed.

If the map is set to zero, that's not really bad.  It just means we used the single injector phase option to get the best overall response in our test car.  Do we leave some on the table...sure...but this is a programmable ECU not a chip.  We're not selling a "tune".  

If you want to precisely locate your injector openings, you need to know where the tooth count resets.  Otherwise you have to tune it by "feel" which is usually what we do.      

SA

[B951S]

SA
When you talk about tooth count reset, I take it that for a 60-2 crank trigger, the tooth reset is basically the -2 teeth, right?

[Shu]

Fwombat

I think you misunderstood me.  My spreadsheet already does all of the calculations.  I however must assume a fuel pulse width based on rpm and manifold pressure.  This can very under different conditions.  Namely accel.  The algorithm on that page is used in that application as an on the fly calculation and they do not use a table.

I agree they using that algorithm it may not be as critical at low rpm accel.  Previously I used the inject as late as possible approach and accel had a significant effect.

[CivicSi2k]

Does anyone have any input on the tooth reset point for a honda?  I've been looking all over and haven't come up with anything.  Even the service manual.

[SA]

SA
When you talk about tooth count reset, I take it that for a 60-2 crank trigger, the tooth reset is basically the -2 teeth, right?

No because that happens twice per engine cycle.  The tooth count only resets once...at the cam sync.

SA

[B951S]

SA
When you talk about tooth count reset, I take it that for a 60-2 crank trigger, the tooth reset is basically the -2 teeth, right?

No because that happens twice per engine cycle.  The tooth count only resets once...at the cam sync.

SA

  Should have known that, I guess what I meant was the -2 teeth on the crank AFTER it sees the cam sync. I thought the cam sync could place anywhere from 5 to about 100 degrees before the TDC sync? I never throught the cam signal would be the significant timing signal for tooth reset for a 60-2 / 1 cam sync set up. I guess I am missing something

[Erich Moraga]

Crap.  Apparently we can't post attachments anymore.  PM me for the spreadsheet, I guess.  Or, if someone were willing to host it...

Shu told me there was another spreadsheet floating around, but I didn't see the link for that, see here is FWombat's...

http://Eclipse.ErichMoraga.com/AEM/FWombat_Injector_Timing.xls

-Erich