Injector Duty Circle (IDC)

[oblark]

Does anyone know what the operating time in milliseconds (m/s) is for whites @ 3 bar and blues @ 3.8 bar

[Dangerous Dave]

Is this for the DIY remapping bud?

[oblark]

Is this for the DIY remapping bud?

Yeap, been reading up on IDC & AFR`s :)

[Dangerous Dave]

So are you after the injector constant for whites and blue then? the duty cycle should be adjusted by the ecu. Or is it the minimum operating time you're after?

[oblark]

So are you after the injector constant for whites and blue then? the duty cycle should be adjusted by the ecu. Or is it the minimum operating time you're after?

The time the injector is energized :)

[Dangerous Dave]

Think that is adjusted/calculated by the ecu bud. There is a minimum opening time and injector constant (the constant is changed for different injectors), as well as voltage correction table for voltage fluctuations plus some others. You can log the duty cycle though to see if it is at the limit.

The injector constant for whites at 3bar is 0.906
The constant for blues at 3.8bar would be 0.797

[oblark]

I found this on one of my searches

"A four stroke engine takes 2 complete rotations of the crankshaft to complete a cycle. The RPM of the motor is what is going to determine the "time". Let us use the example of an engine running at 600 RPM's. This would give us 300 cycles per minute (600 / 2 = 300). Next we need to convert those converted to cycles per second. Because RPM is a "per minute", we need to divide by 60 (60 seconds in a minute). This would be 300 / 60 = 5. We want this number to represent seconds per cycle (the "time) so we would represent this number as 1/5 (or 200 milliseconds, ms) and equated to the engine cycle taking 200 ms to complete.

Now we need to determine the time the injector is energized at this point in the fuel map. Lets just say for ease of understanding that the injector is pulsed at 20ms. This would be (20 / 200 = 1/10 ) 20 (ms injector is directed to pulse) / 200 (time it took for the engine to complete a cycle) would give you = 1/10 OR a 10% Duty cycle"

[Dangerous Dave]

Think that is for more basic systems. The duty cycle will vary for the amounts of fuel needed, motronic calculates this from the MAF and AFR and injector constant, hence some of the people on the VS thread were running at 110% duty cycle which is imposible for the injectors to achieve, so bigger injectors are needed. Best thing to do is log the duty cycle you are running at and check the maximum it reaches on run.

[oblark]

I`ll more and likely start off with the whites and if more fuel is needed fit the blues @ 3.8 bar :)

[Dangerous Dave]

Blues at 3 bar flow the same as whites, they are just a slightly different resistance. So you could up the pressure through the whites I guess and change the constant.

Might be better with greens

[woz]

Think that is adjusted/calculated by the ecu bud. There is a minimum opening time and injector constant (the constant is changed for different injectors), as well as voltage correction table for voltage fluctuations plus some others. You can log the duty cycle though to see if it is at the limit.

The injector constant for whites at 3bar is 0.906
The constant for blues at 3.8bar would be 0.797

Sorry to borrow your thread slightly, but if I were to change my injectors from orange to whites say (I have;>)) Should I need to change the injector constant? I had assumed I might need to thoughit should sort itself out in closed loop mode? Seems to wrok OK and consumption is actially better so haven't worried too much. But how would I do that anyway?
Cheers
Woz

[Dangerous Dave]

Firstly I'm not sure if Motronic 4.3 (850s) has an injector constant unfortunately (it could be built into the MAF values, etc) as I've not done much with 4.3. There is obviously one in the Motronic 4.4 code.

In a perfect world then yes you would need to change the injector constant (which is set at 1 for the orange/red 315cc injectors), as the base fuelling is set for the oranges, but usually the ecu adapts a little to accommodate the increased fuel amount going in. The whites aren't too much bigger to cause a problem.

You're increased mpg is probably out a little bit as the bigger injectors will be open a shorter time for the same amount of fuel as the smaller injectors. There is a seperate constant for the mpg calculation which probably (very basically) uses the time the injectors are open to calculate the amount of fuel being used, so shorter time equals more mpg, thus bigger injectors equals shorter time open and more mpg, but in reality the actual mpg will not change (or even get worse if the ecu doesn't fully adapt to the increased fuel rate). The amounts might be negligble but without testing we cannot know for sure.

Hope this makes sense.

[classicswede]

It would be worth taking a look at your fuel trims and seeing where the long term trim has ended up with the increased fuel flow.

Back to the injector Duty Cycle side of things the normal goal is to be at around 85 - 90% duty cycle max at max load max highest RPM.

[960kg]

Does anyone know what the operating time in milliseconds (m/s) is for whites @ 3 bar and blues @ 3.8 bar


This reading will be for whites @3 bar as is Standard V70 T5 4.4....the other injectors are further down the page but identical.

Anyone know what motor use blues @3.8 and i may be able to look it up?

[stribo]

This reading will be for whites @3 bar as is Standard V70 T5 4.4....the other injectors are further down the page but identical.

Anyone know what motor use blues @3.8 and i may be able to look it up?
ME7 T5s.

[960kg]

Looked up ME7 .....so if blues @3.8bar as mentioned then here are a few examples of the different engines.

In order:

ME7 B5244T3 2002 V70

ME7 B5254T4 2004 AWD V70

ME7 B5234T3 2000 V70