Injector timing

[lagos]

Why are the values so different on the DIYPNP basemap? They seem to be at least 180 degrees off, and only go up to 100kpa, even though the ve table is setup for boost. I tried to adjust the values at idle, and basically saw no effect in terms of fuel change.

injection timing table.PNG

[pit_celica]

I don't think to multiply by -1 is the answer either. To do that would put the value at the top of the rpm/boost at 43°.

I ended up having a little chat with Scott Clark a couple nights ago and what worked out to his liking was adding 360 from holley's values. So that's where I'm going to start. I get what you're saying about WOT timing. 24 psi and 7000 rpm (my highs) are still only at 75% duty cycle though with the 2000 cc injectors so I would imagine there may still be some room for improvement being that they aren't hung wide open.

This is what I ended up with as a starting point

I don't want to be picky on this, but if you want to convert directly from the Holley table to the MS table, the way you did it isn't OK. I'm not saying the values in your table aren't OK, I'm just saying that if you want to keep the same outputs from the Holley table, the way I explained is the right way to do it. Take the 300kPa/8000RPM value for example, which is 137°. This timing correspond to 43° before TDC, which is the way the MS want the inputs to be in the timing table.

So, my conversion of multiply by (-1) and add 180° is the way to go.

The real question is why the algorithm inside the Holley ECU outputs such values at high boost/high RPM. I'm sure there is a logical/physical explanation about why. Anyone who may have an insight is welcome to share.

Sam

[dll67]

Oxygen sensors only read the oxygen content of the exhaust gasses, not liquids. Any raw or unburnt fuel will read a lean condition. Like from fuel injected during valve overlap or a misfire caused by anything to lean or to rich to burn.
Whether being drawn in from Injecting before the intake valve opens or after the intake valve opens, if the exhaust valve is still open it will draw raw fuel into the exhaust affecting readings. This will happen if your engines are running cams with any valve overlap, intake and exhaust valves open at the same time.

How the ECU see's the engine cycle is important.
http://www.msextra.com/doc/pdf/html/Meg ... .4-81.html
Section 4.1.3 describes this.
(Edited to adjust the link)

Crank Degrees as seen by ms3.jpg

0 degrees TDC between compression and power is your "0" mark.
With the engine rotating clockwise from 0 TDC to -180 BDC to -360/360 TDC then to 180 BDC and back to 0 TDC.

Typically the intake valve will open near the end of the exhaust stroke and just before the intake stroke or -360/360. Timing the injector before the end of exhaust stroke would be a negative number -360 to -180 to 0, and timing the injection after the end of the exhaust stroke would be a positive number, 360 to 180 to 0. This image ASSUMES your exhaust valve closes and your intake valve opens exactly at -360/360 TDC, Which they dont.

[ol boy]

From the above picture a value of 270 would be a good starting point for the end point of an injection. Lead the intake valve by some amount of time. Like mentioned a few posts back, the type of injector placement/layout will mean the angle will need to favor more to the -360 to -270 area. My setup has the injector pointed straight down toward the floor of the intake which would require more lead time.

Another thought would be to spray closers to the peak intake velocity to keep fuel from sticking to the floor of the runner.

For the ITB folks... how does the fpr reference engine vacuum? I've found on a few single cylinder engines that moving the injector angle and resulting AFR change was more due to the pressure delta across the injector than finding the most efficient angle.

Ryan

Sent from my SM-G920V using Tapatalk

[Yves]

On my ITB setup I have a pretty good vacuum signal from the vacuum chamber. The FPR follows that exactly.

As for injector timing. Mine are pointed straight at the runner floor as well due to space constraints. It runs rough when injecting fuel when the valve opens. It like some more lead time. Articles I have in my possession suggest the same for maximum power. The element being that it takes time for fuel to vaporize.

I did however find out that the more rpm the less the injection time needed. If I still use a longer time (in ms) before the valve opens the fuel sticks to the walls and this causes popping on decel. The popping could somewhat be reduced by reducing injector timing in relation to the intake valve.

So yes a lot depends on airflow and the way the injector is mounted.

Just my .02$. Opinions may vary.

[72bluetr6]

Are you saying that the degrees in the timing chart state the end of the squirt? So the ECU calculates when to start the squirt? Example: one puts 270 in the chart, and you need 8ms duration to squirt needed fuel, so the ECU takes the rpm and degrees per millisecond, and calculates some higher number of degrees for when to start the squirt?

[ol boy]

Depends on what you have it set to.. you can pick... start, middle, or end. So if we are talking about leading the fuel in relationship to the intake phase then setting the end of spray angle seems to me the smartest less thinking way to do it. As the rpm and load increases the code will naturally start the pulse width sooner and sooner and still end somewhere around the beginning or middle of the intake phase.

That 8ms value will be very dependent on injector placement and orientation to the intake runner. OEM setups with the injector pointing at the base of the intake valve from 2 or 3 inches away won't need much lead time at all.

Ideally as mentioned putting fuel on the intake valve in the middle of the power/exhaust phase will insure the intake valve is at its hottest point and better atomize the fuel.

Sent from my SM-G920V using Tapatalk

[72bluetr6]

Running MS3. I couldn't find where to set default for injector table, end, middle, or beginning of squirt. But I experimented, set values in table to 270-700, all to -350, and all -330 for all RPM ranges for three different tests. Drove around a bit with each table. Much smoother with all injector values at -350 and all at -330. Logs too big to post.

[CRSTune]

Running MS3. I couldn't find where to set default for injector table, end, middle, or beginning of squirt. But I experimented, set values in table to 270-700, all to -350, and all -330 for all RPM ranges for three different tests. Drove around a bit with each table. Much smoother with all injector values at -350 and all at -330. Logs too big to post.

It's located in "Engine and Sequential Settings".

[72bluetr6]

Zipped logs, still too big.

[72bluetr6]

Found it... where to set injector timing. Thanks.

[red-racing]

I have a dyno, I see no change in power between sequential and simultaneous. So I gave up the whole sequential thing. maybe you can save some fuel on low loads

[kingtal0n]

Hello everyone,

I spent a long time trying to understand the table, and still unclear what it means. When the number gets larger, doesn't that mean the event is ending later (retarded timing)? If so, it can be confusing to say "advance the table" which means smaller numbers (counter intuitive).

I was, however, able to determine two things by playing with the values:
1. The throttle response of the engine was GREATLY affected by the injector phase table, in a 2jz-gte application. Off idle response literally felt like night and day, the engine really liked a very specific value I found through experimentation.

2. The other member mentioned finding the "richest value" and I was able to use this advice somewhat effectively, reducing part throttle fueling to some minimal value during cruise that seemed to result with the best fuel economy (on paper). I think this is an ideal method, if you can't make heads or tails of the table (like me).

I found these thread, might help
http://www.efi101.com/forum/viewtopic.p ... 1ff2411e21
http://aemelectronics.com/?q=forum/conf ... tor-timing

Some folks are spraying into an open valve. I am almost positive my best response was achieved by spraying into an open valve. I have heard rumors this might facilitate increased ring wear. also, if you consider that the fuel event is finished before the valve opens, that will mean the fuel will encounter the overlap period, thus larger cam engines might lose fuel this way. Spraying into the open intake valve after the exhaust valve has shut is the only way I can see to guarantee you don't lose fuel to the overlap event. This is just idle conjecture, theory, something to think about.

[pit_celica]

The units are in crank degrees relative to TDC between compression cycle and power cycle. So, here's a few values with their meaining :

0° = TDC between compression cycle and power cycle
180° = BDC between intake cycle and compression cycle
360° = TDC between exhaust cycle and intake cycle
540° = BDC between power cycle and exhaust cycle
720° = 0° = TDC between compression cycle and power cycle

Now, the real meaning of the values in the table really depend if you set you injection timing as "Start" or End". I wouls suggest to use "End".

I would recommend to do not spray fuel in an open valve.
I would also recommend to do not spray fuel during valve overlap.
So, based on this, my take is to always make sure that your end of squirt is always before the opening of the intake valve (which is also before the valve overlap). So, this means that the values should be higher than at least 360°.

Values should then increase vs RPM because the same fuel need the same finite time to evaporate, but less time is available at higher RPM for the fuel to rest on the hot intake valve if the same injection timing is used.

Sam

[dll67]

On a 8 cylinder running sequential and 1 injection per cycle my firmware won't let me set sample past 89.9 degrees without kicking up a settings error.

[kingtal0n]

The units are in crank degrees relative to TDC between compression cycle and power cycle. So, here's a few values with their meaining :

0° = TDC between compression cycle and power cycle
180° = BDC between intake cycle and compression cycle
360° = TDC between exhaust cycle and intake cycle
540° = BDC between power cycle and exhaust cycle
720° = 0° = TDC between compression cycle and power cycle

It doesn't make sense,

first comes TDC compression/power, 0* I am fine with that, compression just ended and power is starting yes?

Then, 180* means that power has just ended, and exhaust is starting. That should be BDC between power and exhaust.
Then 360* means exhaust has ended and intake is starting, which means both valves are open, piston TDC overlap period.
540* intake has ended and compression is starting, BDC before compressing the mixture
finally 720* back to post compression, pre-power, the spark has occured for sure by the time we hit 720* and the mixture is building pressure.

See why I am confused... In my head I am moving the engine forward, but the way you describe the engine is going in reverse as the degrees are increasing.

[CRSTune]

The units are in crank degrees relative to TDC between compression cycle and power cycle. So, here's a few values with their meaining :

0° = TDC between compression cycle and power cycle
180° = BDC between intake cycle and compression cycle
360° = TDC between exhaust cycle and intake cycle
540° = BDC between power cycle and exhaust cycle
720° = 0° = TDC between compression cycle and power cycle

It doesn't make sense,

first comes TDC compression/power, 0* I am fine with that, compression just ended and power is starting yes?

Then, 180* means that power has just ended, and exhaust is starting. That should be BDC between power and exhaust.
Then 360* means exhaust has ended and intake is starting, which means both valves are open, piston TDC overlap period.
540* intake has ended and compression is starting, BDC before compressing the mixture
finally 720* back to post compression, pre-power, the spark has occured for sure by the time we hit 720* and the mixture is building pressure.

See why I am confused... In my head I am moving the engine forward, but the way you describe the engine is going in reverse as the degrees are increasing.

The numbers listed in the table are before (B)TDC. You're thinking after (A)TDC.

So, 360 is 360deg before the start of the power stroke, which is around when the intake valve opens. 720 would therefore be a full engine cycle before the current one.

[krisr]

I think this might be an opportunity for Tunerstudio IMO to clear up the confusion around injection timing and not being able to visualise when it takes place. Phil might be able to create a widget on the injection timing page similar to valve timing diagrams so we can better visualise where injection takes place when plotted against camshaft valve events. I'm sure if we asked nicely, he may put it on the TODO.

[pit_celica]

The units are in crank degrees relative to TDC between compression cycle and power cycle. So, here's a few values with their meaining :

0° = TDC between compression cycle and power cycle
180° = BDC between intake cycle and compression cycle
360° = TDC between exhaust cycle and intake cycle
540° = BDC between power cycle and exhaust cycle
720° = 0° = TDC between compression cycle and power cycle

It doesn't make sense,

first comes TDC compression/power, 0* I am fine with that, compression just ended and power is starting yes?

Then, 180* means that power has just ended, and exhaust is starting. That should be BDC between power and exhaust.
Then 360* means exhaust has ended and intake is starting, which means both valves are open, piston TDC overlap period.
540* intake has ended and compression is starting, BDC before compressing the mixture
finally 720* back to post compression, pre-power, the spark has occured for sure by the time we hit 720* and the mixture is building pressure.

See why I am confused... In my head I am moving the engine forward, but the way you describe the engine is going in reverse as the degrees are increasing.

To facilite the use of these BTDC degree units, think about them as if they were spark advance degree. In your timing map, you specify BTDC degree for spark advance. Ex, 30° in the timing table means 30° before top dead center between compression and power stroke. For injection timing, the same thinking apply.

Sam

[kingtal0n]

So If I am using this properly,

when number is increasing in table 340 -> 350* I am giving the fuel more time to sit on the intake valve, injecting sooner before it opens.

And this is closing my window for total injection time. Will I squeeze more duty out of an injector by allowing it to spray well into the intake valve open position? i.e. by Decreasing the table 330* -> 310* -> 300*