[TD350]

So I'm going through the learning process for this ecu and I came across the injector phase option. I've acquired a couple tunes from others just to study the accel enrichment and other stuff, but I noticed all the tunes have the injector phase the same as the base cal. The base cal phasing looks like this:

It should be noted that the HO firing order is 1-3-7-2-6-5-4-8. If you subtract 1 from each number it would be 0-2-6-1-5-4-3-7. Compare to the base cal phase numbers 0-3-1-6-5-4-2-7 then the injector firing sequence is wrong, unless I'm mistaken. Anyone elaborate on this? Or do a lot of people have injectors firing at the back of a closed valve?

 

[mld54]

Old thread but I will reply anyway

That is the injector options setting for setting up the firing order, and that is correct for a HO 1-3-7-2-6-5-4-8 firing order. The column on the left numbered 1 through 10 are the cylinders. the value entered is the firing order 9 and 10 aren't used because it's a 8 cylinder. 0.00 teeth is 1st in the firing order cyl 1, 1.00 teeth 2nd cyl 3, 2.00 teeth 3rd cyl 7, 3.00 teeth 4th cyl 2 and so on for the rest of the firing order.

The actual phasing is another map where you can adjust when the injectors fire in the 720 degrees of the engine cycle, basically setting the injector timing, it ranges from -360 to +360 degrees. Low rpm you can calculate somewhat close from the valve timing events. I use the end of the injection event to calculate

I'm working from memory, I haven't run the AEM for several years and don't have the software on this computer. If I did I could be more help. I may still have it on a old laptop some where if you need more information.

 

[TD350]

I found it interesting that a few completed tunes I've downloaded from other users, used the base cal injector firing teeth, and the phasing graph was flat +359 degrees.

I'm still trying to figure out how to properly set the injector phase teeth value so that at idle, the injector opens as the intake valve opens. From there I can use the phase graph to trigger the injectors opening earlier for higher rpm's.

 

[mld54]

Phase teeth is for firing order only. the phasing map (graph) is what you use to control when the injector opens. I have found that my car works best at idle when the injector fires when the piston is half was down the intake stroke, higher air velocity. Some people tune at idle by adjusting phasing to the richest reading with fixed fueling at idle.

Depending on injector size, at higher rpm the injector may need to be open longer than the intake valve is open. that is why I like to work from when the injector closes. Bigger injectors give you a wider tuning window to complete the injection event while the valve is open.

 

[TD350]

I read on the AEM forum to set fixed ignition timing to zero then start the car and take note of the Ign #01 Firing Loc parameter. This will tell you which fuel tooth the EMS sees when the #1 cylinder is at TDC compression. So add 4 to that (for 8 teeth per revolution) and that is your TDC exhaust. I did this and found my Ign #01 Firing Loc to be 0.11 fuel teeth. Then set the Injector Phase option to 4.11. I guess this sets the phasing graph 0 degree to actually be TDC compression.

I guess you could cut viewing holes in the distributor cap and use a timing light triggered by the injector harness to actually identify where each injector fires as well. My timing light doesn't sense the injector wire current though.

 

[mld54]

I don't have the software in front of me and it has been years since I have used it. I'm trying to work from memory, with that being said I think you are over thinking it. There are better places to put your effort in to the tune.

I would think that at low rpm and idle the best time to inject would when the piston is at its highest speed on the intake stroke (highest air flow). That would be when the piston is in the middle of the intake stroke and the crank throw is 90 degrees to the cylinder. That should be someplace around -270, start there lock the fueling and adjust phasing up and down until you get the richest reading on the wideband.

I have a friend that works for one of the big engine management companies, we were talking about this. He said that on high HP nitrous engines they have seen 15-20 HP on 700 plus engines w/o nitrous. These engines had huge injectors that shortened the injection time enough to allow some adjustment during the time the intake valve was open. This was after everything else was optimized.

I feel that calculating will only get you in the general area, things like valve overlap, air mass , ram effect, injector spray pattern plus many other things affect when the best time to inject is. Many systems are batch fired, there are injectors spraying when valves are closed, open and everywhere in between. Sometimes on sequential systems they spray on a closed valve to cool it, higher rpm the less difference it makes. You said yourself many people are running with the phasing map flat and don't know it. In my opinion for what it's worth (probably not much) anything above low rpm needs to be done on a dyno.

 

[TD350]

I understand. I'm just trying to maximize driveability as it's just for street use at the moment. Don't have dyno access but there's some long hills nearby.

 

[mld54]

If you get everything else right, you will never know the phasing isn't tuned to perfection. It won't be something you can feel with the butt dyno. It would need to be on a dyno held at steady state and tune for that rpm cell, then move to the next cell and tune repeat through the rpm band