Injector Phasing Information

[SA]

I've been noticing a lot of questions recently on injector phasing.  There's lots of information (and even more misinformation) scattered around so I figured I'd start a new thread to consolidate it.  To start off, here's a brief explanation of how injector phasing works in our software:

It actually depends on where your cam sync falls relative to TDC. This is best explained using an example:

If option Inject Tooth #01 = 0.00 teeth
and the Inj Adv Map = 357 degrees
and option Injector Phase = 0.00 teeth

The injector will open at the first significant crank edge following the cam sync edge. If the falling edge is your significant edge, the opening time will correspond to the first falling edge of the crank signal. The Inj Adv Map has a range of -360 degrees to +357 degrees. The smaller the value, the later the injector fires. You can monitor the actual opening position of the injector by logging the parameter Fuel Inj #01 Open in teeth. If all of the above is true, this parameter should read 0.00 teeth.  So to know exactly where your injection events are happening relative to TDC, you need to know where your cam sync event happens because everything is based off of that signal.

...and here's some information specifically for the DSM guys:

The DSM 30-13XX timing pattern control is a little more complicated since it doesn't have a single cam sync pulse.  Both the rising and falling edges of the cam signal are significant.  These cars have several evenly spaced teeth followed by a wide tooth on the cam. In this case, if all of the above is true, the injector opening will coincide with the first falling edge of the crank sensor signal following the wide cam tooth pulse.

SA

[Erich Moraga]

The injector will open at the first significant crank edge following the cam sync edge. If the falling edge is your significant edge, the opening time will correspond to the first falling edge of the crank signal. The Inj Adv Map has a range of -360 degrees to +357 degrees. The smaller the value, the later the injector fires. You can monitor the actual opening position of the injector by logging the parameter Fuel Inj #01 Open in teeth. If all of the above is true, this parameter should read 0.00 teeth.

Since the Inj Adv Map applies to all of the injectors, the only way to advance the secondary injectors specifically (to compensate for being further upstream in my case) would be to modify the inject tooth values relative to the primaries, from my understanding.

I spoke to a tech about this a year ago and he had no idea what I was talking about.

I can run my car with just the secondaries and modify the "Injector Phase" value as a sort of proof of concept, per the context sensitive help:

"Injector Phase - ...synchronizes the injection event to the valve opening angle for best emissions and throttle response. Move this number up or down to obtain the best idle, and throttle response. For fine tuning of this use the injector angle map. Changing this value moves all of the injectors advanced or retarded in relation to TDC."

-Erich

[SA]

Since the Inj Adv Map applies to all of the injectors, the only way to advance the secondary injectors specifically (to compensate for being further upstream in my case) would be to modify the inject tooth values relative to the primaries, from my understanding.
-Erich

Yes.  This is true.

SA

[BLKMGK]

Scott, a feature request please!

In a competitor's software they have a mapping that allows the user to tell the system at what point they want the injector to spray. This is in degree of crank advance and th euser need not know anything about tooth counts or anything specific about what's going on under the hood. They simply need to enter the number of degrees they feel is optimal and the software calculates what's required unbeknownst the to the user. Would it be possible for the AEMPro software to be updated to do this? IMO this would be much simpler for the end user and much easier for you guys to explain without having to caveat different platforms. Make sense?

It's Autronic I'm told that does this BTW.

[Shu]

It takes a little work to figure your tooth vs degree settings but after you've figured those out you can specify the degree of firing the injector.  I wrote a somewhat complicated Excel spreadsheet that that would be very helpful. <http://forum.aempower.com/bbs/viewtopic.php?t=8985&highlight=>

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

[B951S]

Is this true even if you are using a missing tooth TDC singal on the crank sensor and a single cam sync? Surely, in this case, the injector will open at teh first significant edge after the can sync AND the TDC sync, correct?

[Tony the Tiger]

It takes a little work to figure your tooth vs degree settings but after you've figured those out you can specify the degree of firing the injector.  I wrote a somewhat complicated Excel spreadsheet that that would be very helpful. <http://forum.aempower.com/bbs/viewtopic.php?t=8985&highlight=>

I noticed on the spreadsheet that you have indicated cyl#3 at TDC compression is located at 1.8 tooth.

But when I checked the cam sync to crank tooth relation, 1.8 tooth is TDC #4.  The Honda cam pick up is sync'd just before cylinder #4 reaches TDC compression.   I just want to find out if it was a typo, or would it affect all the data you have calculated on the spreadsheet regarding injector phasing.  

Or have a I made an observation error?  I am basing this on a spare distributor I have in my hand and doing the observation there.  Much respect for spending time and sharing the info with us by the way

[FWombat]

The injector will open at the first significant crank edge following the cam sync edge. If the falling edge is your significant edge, the opening time will correspond to the first falling edge of the crank signal.

How does this algorithm compare to the ignition phase settings?  Are the ignition firing locations determined in a similar manner?  Are the injector teeth related in any way to the spark teeth?

- Brian

[SA]

The injector will open at the first significant crank edge following the cam sync edge. If the falling edge is your significant edge, the opening time will correspond to the first falling edge of the crank signal.

How does this algorithm compare to the ignition phase settings?  Are the ignition firing locations determined in a similar manner?  Are the injector teeth related in any way to the spark teeth?

- Brian

Same concept for ignition phasing.

SA

[FWombat]

The injector will open at the first significant crank edge following the cam sync edge. If the falling edge is your significant edge, the opening time will correspond to the first falling edge of the crank signal.

How does this algorithm compare to the ignition phase settings?  Are the ignition firing locations determined in a similar manner?  Are the injector teeth related in any way to the spark teeth?

- Brian

Same concept for ignition phasing.

SA

Fantastic.  So if we set the Inject Tooth value for each injector to the same value as the Spark Tooth value for coil of the same cylinder, and Ignition Sync == Inject Phase, the two events (spark and injector open)should happen simultaneously, right?  

Not that I would actually do that, or course, but it's useful as a reference point.  

- Brian

[SA]

It's been a while since I've looked at both signals in that context.  There may be a slight offset (only measurable with an O-Scope) but yes...basically that statement would be true.

SA

[Shu]

"TDC #3 is at tooth 1.8" was just a note to myself that I should have taken out for the generic posted version. In my case (Honda OBD0) that's the value that I came to.  The spreadsheet only requires that EACH of your injectors are sync'd to TDC power stroke.

[CivicSi2k]

I tried to monitor the opening teeth for each injector but they all say "200" except for inj #1?

[SA]

I just ran a 1010 ECU on our test bench.

Injectors 1, 2, 4 and 5 are activated.  I set option Injector Phase to 0.00 Teeth (normally 3.00 in base map) and set all values in the Injector Adv Map to 357 degrees.

Monitoring the fuel injector opening PARAMETERS:

Fuel Inj #01 Open = 12.00 Teeth
Fuel Inj #02 Open = 0.00 Teeth
Fuel Inj #04 Open = 18.00 Teeth
Fuel Inj #05 Open = 6.00 Teeth

These correspond exactly to the following OPTIONS:

Fuel Inject Tooth #01 = 12.00 Teeth
Fuel Inject Tooth #02 = 0.00 Teeth
Fuel Inject Tooth #04 = 18.00 Teeth
Fuel Inject Tooth #05 = 6.00 Teeth

This means injector #2 opens at the first rising crank edge following the rising cam sync edge.  Injector #5 opens 6 teeth (180 crank degrees) later.  Injector #1 opens 6 teeth later...and so on.

SA

[FWombat]

I just ran a 1010 ECU on our test bench.

Injectors 1, 2, 4 and 5 are activated.  I set option Injector Phase to 0.00 Teeth (normally 3.00 in base map) and set all values in the Injector Adv Map to 357 degrees.

Monitoring the fuel injector opening PARAMETERS:

Fuel Inj #01 Open = 12.00 Teeth
Fuel Inj #02 Open = 0.00 Teeth
Fuel Inj #04 Open = 18.00 Teeth
Fuel Inj #05 Open = 6.00 Teeth

These correspond exactly to the following OPTIONS:

Fuel Inject Tooth #01 = 12.00 Teeth
Fuel Inject Tooth #02 = 0.00 Teeth
Fuel Inject Tooth #04 = 18.00 Teeth
Fuel Inject Tooth #05 = 6.00 Teeth

This means injector #2 opens at the first rising crank edge following the rising cam sync edge.  Injector #5 opens 6 teeth (180 crank degrees) later.  Injector #1 opens 6 teeth later...and so on.

SA

I thought I had a handle on this, but now I'm confused again.    

I would have expected the values you describe above to occur with the Inj Advance map at 0 degrees, not 357.   With the table at 357, wouldn't you expect the Open values to be 360 degrees (12 teeth) out of phase with the Fuel Inject Tooth settings?

- Brian