Inj Firing angle ... again

Yapudo
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Inj Firing angle ... again

Postby Yapudo » Wed Jan 06, 2016 12:29 am

Hi folks and happy new year,

I've read a lot of other topics on this subject and never found a clear answer:

Does this angle refers to ignition top dead center?
because i think values for performance need to be arround 250-300° (or less in some cases), if we are talking about ignition top dead center.
(in OEM cars there are only 2 timing to inject when valves are closed or open depending on load and pollution)

and why does we do not take into account load here?
as at low load air will be slow (so more time for fuel to enter the cylinder) and in high load, fast air flow help fuel droplets to enter quickly in cylinder.

JohnPS
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Re: Inj Firing angle ... again

Postby JohnPS » Wed Jan 06, 2016 1:59 am

angle is in BTDC on compression stroke...

Based on your cams calculate the point the intake valves are opening and add some more degrees...


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Yapudo
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Re: Inj Firing angle ... again

Postby Yapudo » Thu Jan 07, 2016 2:25 am

this angle is refering to closing of injector, so you need to aim closing of the intake valve (and add some degrees before to not put fuel droplets on valve after closing, to avoid wetting of duct walls)

or is it opening of injector, and in this case we need some load value correction to set it during valve opened time. ???

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HaltechMatthew
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Re: Inj Firing angle ... again

Postby HaltechMatthew » Mon Jan 11, 2016 11:38 am

It is End of Injection and you usually you need to end injection much earlier than that.

You need to end injection while the air flow is still high to give better atomisation and a more homogenous mix in the cylinder. Light load it will be before the valve opens, around 360 to 450degrees. High load you can go more retarded due to air velocity still being quite high at higher valve lift. If you end the injection too late (retarded) then some fuel will not make it past the valve. This usually shows as a slight hesitation under transient conditions.

This table is scheduled to be expanded to 3D in a future update.

Yapudo
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Re: Inj Firing angle ... again

Postby Yapudo » Mon Jan 11, 2016 8:25 pm

Thank you Matthew,

but can you confirm that the start angle (when we start to count this angle) is ignition TDC ? (or end of compression)

i've planned to optimize this setting on dyno anyway (as i've learned how oem do this too, it's like "richiest" point but with some pollution management).

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HaltechMatthew
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Re: Inj Firing angle ... again

Postby HaltechMatthew » Mon Jan 18, 2016 3:47 pm

The starting point is back-calculated from the end point and could be anywhere. We are not dealing with Direct Injection so we do have the full 720deg crank rotation to choose when to start firing. It is far more important to tie the ending. Get it wrong and all of the fuel does not make it to combustion, giving a lean condition.

Yapudo
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Re: Inj Firing angle ... again

Postby Yapudo » Tue Jan 19, 2016 12:07 am

sorry this miss understanding, by starting point i was counting backward from ignition to end of injection.

I'm ok that we set the end of injection.

But to be clear this "end of injection angle" refere to:
"ignition TDC" to "end of injection"?

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HaltechMatthew
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Re: Inj Firing angle ... again

Postby HaltechMatthew » Tue Jan 19, 2016 1:01 pm

Correct.

Yapudo
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Re: Inj Firing angle ... again

Postby Yapudo » Tue Jan 19, 2016 8:21 pm

Thanks a lot, now it's clear :wink:

And i hope it could help some people

MarekS100
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Re: Inj Firing angle ... again

Postby MarekS100 » Wed Feb 17, 2016 5:56 am

HaltechMatthew wrote:It is End of Injection and you usually you need to end injection much earlier than that.

You need to end injection while the air flow is still high to give better atomisation and a more homogenous mix in the cylinder. Light load it will be before the valve opens, around 360 to 450degrees. High load you can go more retarded due to air velocity still being quite high at higher valve lift. If you end the injection too late (retarded) then some fuel will not make it past the valve. This usually shows as a slight hesitation under transient conditions.

This table is scheduled to be expanded to 3D in a future update.


Hi Matthew, I have tried to change injection angle, because I have lean spot when light transient conditions occurs (throttle applied, TT-DeltaLoad<0.5, without TT activation, MAP change from 0,3 to 0,8bar). The lean spot takes ca. 1s and goes to AFR=15.4 (Target=14.6). The injection angle from base map for subaru impreza 99-00 was increased by ca.140° to 550° wihtout any significant improvement. I have also no success with changing transient throttle parameters like delta dead band and decay rate.
Engine is standard subaru EJ20 with ball bearing turbo IHI VF23. ECU Haltech Sport 1000.
Any ideas?

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HaltechMatthew
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Re: Inj Firing angle ... again

Postby HaltechMatthew » Mon Feb 22, 2016 12:56 pm

Probably not related to the angle. I would be looking at other sources of the problem, maybe too much sensor filtering or just plain not enough enrichment.


On a side note. Injection Angle is 3D in Elite series from v2.09 firmware due shortly.

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Re: Inj Firing angle ... again

Postby ms5000 » Wed Dec 21, 2016 6:01 pm


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Just2FasTT
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Re: Inj Firing angle ... again

Postby Just2FasTT » Fri Jul 07, 2017 6:45 am

Am i right if i say the end of injection at highest air velocity (increasing valve lift) or even a bit later will result in a more homogenic air fuel mixture, less knocking and a cooler combustion camber because of the fuel evaporating location?
What is the best method to find this perfect firing angle on high load and rpm?
are there any examples how a rpm/load tuned firing angle map should look like on a turbo engine?

i was running the values of your 1.8T beetle base map until now and i think there could be a lot of improvements made.

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HaltechMatthew
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Re: Inj Firing angle ... again

Postby HaltechMatthew » Fri Jul 07, 2017 11:07 am

Centre of injection at the highest air flow is more ideal. But there is a great amount of guesswork and estimation involved. You have to think about what the air is doing, then the expected travel time from injector to valve, and many many more things, all to find a 1% improvement.

The end result though is the difference in getting it completely bare-ass wrong and getting it perfectly correct is minimal, but the differences depend greatly from engine to engine, and injector to injector, and cam specs, etc..etc..etc...

I would spend the time looking at other areas of the tune instead.

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Re: Inj Firing angle ... again

Postby CorrPerformance » Wed Jul 12, 2017 9:03 am

So reading the previous post lends me to believe that is the final adjustment that one should make after the engine has been tuned to the best of it capabilities?
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