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Guest |229|

Injector timing..

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Guest |229|

Hi all.

I just noticed in my setup. Under "Fuel" - "Injector timing"

The timing is set at 390 degrees BTDC. I can not find any real info about this part in manual.. And the numbers i read, when i see something that could be something, is 360 degrees.

So is it correct at 390? Or should it be changed.. My car has driven fine so far with the setting of 390 degrees.

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Guest |252|

"This specifies the injector timing to be used throughout the entire operating range. The units are degrees before top dead centre (BTDC) with reference to top dead centre between the compression and power stroke. Therefore 360 represents TDC between the exhaust and inlet stroke."

From the manual. Is more info than that needed?

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For the smoothest running engine all the fuel should be injected just before the inlet valve opens. This is around 330 degrees on most engines. With very big injectors is possible to inject the fuel while the inlet valve open. This can give more power.

You can select between these three options in the software,

End of Injection

Start of Injection

Center of Injection

To inject all the fuel before the valve opens select End of injection and set the degrees to suit your camshaft. You can also select a table or one single zone. If using a table you can correct for lag due to rpm. Example:-

1000--3000--5000--7000 RPM

-330---300---280----260 Degrees

Start of injection can be used to inject all the fuel while the value is open. Again you would use a value around 330 degrees.

I wrote a program many years ago to let you work out setting based on your cam specifications and injector time. This is that program http://www.vi-pec.com/software/InjectRange.exe

Ray.

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Guest |229|

Now im even more confused.. :?

I have this data on my cams used for intake. Cam duration: 240 degrees. Lobe centre angle: 120 degrees.

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Guest Dave-Kriedeman

You need to find out the openning and closing degree events of your inlet valve to use this program.

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The cam timing information you want is the intake value opening and closing degrees at the running tappet clearance, and not at 50 thou as most cams are rated. Cams specifications normal have the opening and closing in degrees from TDC of the exhaust stroke.

Example:-

Intake Opens 37 BTDC

Intake Closes 79 ATDC

Exhaust Opens 90 BTDC

Exhaust Closed 36 ATDC

As these values are from TDC on he exhaust stroke (360 degrees into the engine cycle) you need the do the following calculation to get the opening value in crank shaft degrees.

360 - 37 = 323 degrees

To find the closing 360 + 79 = 115 degrees.

Ray.

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Guest |99|

Injector timing is one area where there seems to be a lot of different opinions that go something like this.

The important thing to remember is that it is fuel vapour that burns not liquid fuel.

1) Inject when the inlet valve is closed and use the heat in the valve to help vapourise the fuel before the valve opens. Potential problem: Not all the fuel vaporises and pools on the back of the valve. When the valve opens some of the fuel goes out the exhaust during the overlap period and not all the pooled fuel vapourise during the compression stroke. This could be worse on large valve overlap engines.

2) Inject when the inlet valve is open but after the exhaust overlap period. This will require big injectors to get all the requried fuel in before the inlet valve closes. This may give the maximum opportunity to vapourise the fuel as it will be in droplets as it enters the cylinder. (allowing for some coalesence due to impingement as it goes past the valve)

3) Have the end of injection complete before the inlet valve closes and let the ECU work out where to start and accept that some fuel will go out the exhaust.

I have found that on light loads injecting when the inlet valve opens but after the exhaust valve is closed gives smooth engine results.

Unfortunately, the truth is probably a mixture of all the above and changes depending on laod and RPM. It just needs to be played with until the engine runs at it preferred sweet spot for each load & RPM.

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Guest |252|
Example:-

Intake Opens 37 BTDC

Intake Closes 79 ATDC

Exhaust Opens 90 BTDC

Exhaust Closed 36 ATDC

When setting the injector timing to end at the time where the intake valve opens, would'nt it be

360 + 37 = 397 degrees

Since the exhaust stroke is 360 degrees btdc of compression stroke, and the intake valve opens an other 37 degrees btdc of the exhaust stroke?

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Guest |252|

Assuming I would want to have the end of injection occur at the moment the intake valve opens, the value I should input into ViPEC would be ____. The help file says that the units are degrees BEFORE top dead centre referenced to the top dead centre between the compression and power stroke. The valve opens 397 degrees BTDC of the compression-power stroke, which is the same as 327 degrees ATDC of the compression-power stroke. Just making sure the 397 would be what I would to enter into ViPEC.

Brian

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Guest Hic

Brian

from the manual:

This allows the injector timing to be altered with engine speed and load. The units are degrees before top dead centre (BTDC) with reference to top dead centre between the compression and power stroke. Therefore 360 represents TDC between the exhaust and inlet stroke.

So, if you want your injection to finish at the moment the intake valve opens, take the 37 from 360, so 323deg will be your end injection angle.

Hrvoje

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Guest |229|

Opens TDC, closes 60ABDC. Duration = 240

This is what info i got from skylinesasutralia.com ...

So the setting i should use would be 360?

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Guest |252|

Reference: Top dead centre between the compression and power stroke

Units: Degrees BEFORE top dead centre (BTDC).

Assuming the sketch I drew is correct, the valve opening occurs 397 degrees before top dead centre referenced to the compression and power stroke.

To me it seems that the only logical way the number would be 323 would be either

A) The engine is turning backwards

B) The Units are degrees after top dead center (ATDC)

Ray, can you shed some light into what the answer is? :)

Brian

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Guest |395|

Ray,

please, can you confirm that this injector timing is ok.

As you stated it is always BTDC 360 - cam timing.

i have cams

opening at 18deg

closing at 59deg

correct timing should be then 342deg? (or is it 360+18deg= 378deg?)

Also what timing do you recommend for higher RPM, 2000, 3000, 4000,... 8000 rpm

aim asking because this confuses me:

To inject all the fuel before the valve opens select End of injection and set the degrees to suit your camshaft. You can also select a table or one single zone. If using a table you can correct for lag due to rpm. Example:-

1000--3000--5000--7000 RPM

-330---300---280----260 Degrees

i think that this should be 330---360---400---440 or im wrong?

or i can just put it in options on single zone (instead to table) to value 342deg?

also, if this values are changed, do i have to make remap? (AFR should stay same, i mean, amount of fuel is same, or im wrong?)

__

i have small idle issues, and fuel cut and injection timing where first two things to look at it , and of course i set fuel cut to low and injection timing was at 300deg (to early?)

i set this to 340deg (after this engine starts with less cranking, is that just my imagination?), and fuel cut off to 1500rpm, and i solved idle problem which was, when going down hill and when fuel is off (above 1500rpm in my first to low case 1200rpm) when i press clutch engine shuts down every time.

Ok, thing is, car works perfectly (Thanks Hic) but thing with idle starts to be pain in the ass and i want it to work perfect, even now when i set this two things (injector timing 340deg and fuel cut off to 1500rpm), when driving downhill and when press clutch, engine falls to 400rpm (i think this is very low and that there is very big chance for engine to shut down), and then back to 830rpm where idle speed is...

Thing is, even if i did set this, engine shuts down in 1 of 10 times, so when im braking with engine before traffic lights, it happens that engine shuts down, and that starts to nerves me.

How can i prevent dropping rpm below 800rpm?

Idle is on open loop, and works fine at 830rpm, and it works stable through all temps. (from 20deg to 100deg C)

sorry for hijacking thread but can you try to help with advice? (after all it is related to injector timing) This takes lots of time and i dont want to bother Hrvoje, since we are far from each other and (he did hell of a job on my car, Hrvoje, thanks again) im little bit boring, everything needs to be "perfect" :bag:

thanks

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i think that this should be 330---360---400---440 or im wrong?

You are correct.

To be honest injection timing is not critical. In most cases the injectors are open for such a long period in the engine cycle, it does not matter when the start and end.

If you are looking for the best exhaust emissions during light load driving, then there is something to be gained by using the correct setting. I have my doubts there is any power to be gained, as I have never seen it.

It is important that you use the ignition retard for overrun to make it smooth. I find -10 works well.

I told Hrvoje last night that he is not tuning an Autronic and to not put ignition ramps for the idle timing. The ignition table must have higher values just like the stock ECU. The idle sites and any overrun sites around idle, should have the same value like 16 deg. That way the PID idle control can do its job and not get messed around by ignition ramps.

Ray.

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Guest |395|

Thank you for your fast reply and explanation,

so if i get this correct, it should be 360deg + cam timing? or is it 360 - cam timing, but injector timing should rise with RPM and not fall ?

(2000---4000---6000---8000 RPM) ~~

(360-cam timing --- 360---400---440)

Also, im not aiming for highest power, im ready to lose 10hp to get smooth engine work through all RPM range...

Im not using transient ign retard at all :( is it problem ?

So I started to dig for this "injector timing" option because of idle. Since i have very very good tuned car, only that damn idle... and it started to annoy me so much, that i had to do something. (it was not that big problem, but Hrvoje calls me mr. perfect, then you know where is problem, in my head...)

For beginning i started with fuel cut off and injector timing, and it was better, and engine starts with less cranking, only, problem stays, RPM falls below 500rpm, and then quick returns to 800 rpm to idle. Since it is too risky for engine to shuts down every time, yesterday i decided to go from open loop to closed loop, spend 3-4 hours for setup ...

And almost i manage to get what i want, smooth idle... It does work smooth, when i press clutch, rpm drops to 1000rpm, and then (after sec or two) vipec correct idle valve to correct value (800rpm)... and it does it smooth.

New problem is when i start cold engine, engine works nervous, and when engine fan turns ON, i have same problem as i have before when press clutch, RPM drops to 400-500rpm, yes i did set engine fan step to 2% and it does rise rpm for that 2%, but only for a moment engine RPM drops to 400-500rpm, and then rise for that 2%, and i cant get it why, i didnt have that problem before, in open loop...

I do not know whether the following observations is correct, but, i have set base base position solenoid table to 2% more through whole RPM range than engine needs to work on default RPM that i enter in idle table . Observation is, when i press clutch, idle valve opens to duty cycle i have enter, and then after 1sec, corrects idle to value i have set. I didnt know that it works like that? (when idle valve opens, it first opens to value entered in duty cycle, and then is trying to correct RPM), also i tried to enter with exact value (for 800rpm i need 18% and i set 2% more, in this case, exact 18% entered), and i get same problem as in open loop, rpm drops for 400-500rpm. (i think that 2% more in duty cycle table solved problem).

For test, i drove downhill, engine runs 3000rpm (fuel cut off), i press clutch, and engine rpm falls to 1000rpm, and then after second or two i get smooth transition to 800rpm. (before in open loop i have drop to 500rpm or engine shut down) During that, im reading idle status, and it started with value entered in duty cycle.

Now, Im happy with configuration i made until now, it needs little bit of yours experiences to get it done properly.

Oh, yes, ignition table is fine, it is on 20deg in whole range of idling. Is it to much?

edit:

here is screen shot of closed loop idle speed control

idlespeed001.th.jpg

and things i play with, and with this config i get best results, maybe you can suggest to change something

idlespeed002.th.jpg

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Guest |395|

Yes, thanks Hrvoje

I was searching forum for injector timing, and i found this topic, and i was not sure about timing that Ray wrote (330---300--270--240). I dont know it was not logic for me, so i asked, and i explain why i need it. It was related to my idle...

I didnt want to bother Hrvoje any more :roll: and that is why i asked, sorry if i make some trouble...

Regards ...

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Guest |97|

Rather than speculate on the fundamental correct injector timing based on camshaft timing, MY preferred method is to establish what I consider is the best injector timing based on smallest injector output for richest measured lambda reading. This, in my opinion tells me that the maximum amount of fuel at the given load and speed is being consumed by the engine.

Trends soon form, and it is never the same value across the board.

Injector location (distance from the valve) and angle of delivery effect this just as much as camshaft profile. Larger overlap cams are even more sensitive to injector timing as reversion can blow the fuel right back out!

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Guest |229|
Yes, thanks Hrvoje

I was searching forum for injector timing, and i found this topic, and i was not sure about timing that Ray wrote (330---300--270--240). I dont know it was not logic for me, so i asked, and i explain why i need it. It was related to my idle...

I didnt want to bother Hrvoje any more :roll: and that is why i asked, sorry if i make some trouble...

Regards ...

I am happy you asked. Because the result is even more info on the subject. ;-)

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