Injector Flow Testing Voltage - How Important?

[Yves]

Seeing the variance in dead time between injectors, I doubt that cc'ing vs measing weight and then calculating the cc's makes a lot of difference, my .02$.

I have a question though : I got dead times going from a high 0,58 ms to a low 0,51 ms. At what do you set the dead time on an ms 2 system ? Average, highest or lowest ?

When making a spreadsheet that made it possible to compare the effect of a programmed dead time on the injected volume, for me the lowest value was best. Any drawbacks to that approach ?

[LAV1000]

Seeing the variance in dead time between injectors, I doubt that cc'ing vs measing weight and then calculating the cc's makes a lot of difference, my .02$.

I have a question though : I got dead times going from a high 0,58 ms to a low 0,51 ms. At what do you set the dead time on an ms 2 system ? Average, highest or lowest ?

When making a spreadsheet that made it possible to compare the effect of a programmed dead time on the injected volume, for me the lowest value was best. Any drawbacks to that approach ?

cc versus grams makes no difference, I used grams because i had no precise measuring cup.
When working in one of this units keep to it and convert at the end, don't keep switching between them.
The difference between them is one costant factor.
So this has no effect to determine deadtime.

If you set the MS unit to semi sequential you can set the deadtime for 4 injectors seperatly.

I would go for te biggest deadtime.
MS uses deadtime and adds it to the opening time.
If real deadtime is less you get more fuel in the engine, mostly not a big problem.
When real deadtime is bigger you get less fuel in the engine, can cause a lot damage.

[Yves]

OK, logical explanation.

If I remember correctly I cannot run semi sequential on a V8.

[dontz125]

If I remember correctly I cannot run semi sequential on a V8.

Correct me if I've misremembered, but aren't you using an MS2 with all 4 fuel channels? 4 channels allows you to run semi-sequential on a V8.

[LAV1000]

If I remember correctly I cannot run semi sequential on a V8.

You might be right on this.
But you can probably drive them in 4 banks (4x2).
And match the 2 injectors for each bank.
All of this depends on youre set up and hardware, you have to find out yourself I'am no expert on that matter.

[Yves]

If I remember correctly I cannot run semi sequential on a V8.

Correct me if I've misremembered, but aren't you using an MS2 with all 4 fuel channels? 4 channels allows you to run semi-sequential on a V8.

I'm using the relay board. I have 2 channels (INJ 1 and INJ 2). Each has 2 connectors. I suppose the 2 connectors are opened towards ground simultaneously so in effect only 2 channels. I think that ms2 with semi sequential had something to do with using 2 injection pulses per cycle and spreading them apart. Maybe not accurate but something along those lines.

[ErnieJones]

Maybe I'm on glue but it looks to me that with MS2 all you can do is enter a value for 13.2

InjectorDeadTime.gif

I'm about to send the injector out for a clean & dead time test and I can specify which voltage to use so I'm guessing it's going to be 13.2 as this is all I can enter into Tuner Studio...unless I'm missing something I think this is what I will do. Once I get the figure back for 13.2 enter it in, and hopefully all will be sunshine and puppy-dogs

I doubt it will be worse then the guessing I am doing now If it's in the ball-park it should be much better then what I have. I do take comfort in this statement though;

I'am also running EFI on motorcycle. Bike would not idle well on the injectors when using the spec data for these injectors. Engine did quit at an AFR 13. After flow testing and getting dead time spot on it quits at an AFR 17.

[pit_celica]

In MS2, you can only enter the deadtime at 13.2V and you can enter the "slope" of the curve in ms/v using the "Battery Voltage Correction" value. So, the final output can only be a straight line curve of deadtime vs voltage. In MS3, instead of one point and a slope, you can define a 6 points curves for deadtime vs voltage.

Sam

[ErnieJones]

Hi Sam - thanks for confirming that for me

I just saw something interesting though...... I installed a new lithium battery the other day and I decided to check whether the battery voltage and the voltage reported by Tuner studio (batteryvoltage) were the same....they're not.

The battery voltage is almost exactly .5 volts higher then that being reported by Tuner Studio....

[LAV1000]

Hi Sam - thanks for confirming that for me

I just saw something interesting though...... I installed a new lithium battery the other day and I decided to check whether the battery voltage and the voltage reported by Tuner studio (batteryvoltage) were the same....they're not.

The battery voltage is almost exactly .5 volts higher then that being reported by Tuner Studio....

Have you checked this also with the old battery ?

[kaeman]

when checking voltages, remember checking the voltage at the battery isn't the same as checking the voltage at the power wire into the ms unit. they might be several volts different depending on alternator routing and fuse panel locations for various components. also when doing the dead time testing it doesn't matter what some other tester shows for a dead time only what your unit and testing on your vehicle determined the correct dead time to be.
In other words the dead time you get using your megasquirt and injectors should be plotted into the spreadsheet and then used to configure your ms controller. you will have more accurate results.
good luck.

[ErnieJones]

Hi Guys!

I'm sending the injector out to have it cleaned and dead time tested - I just can't spend the time plotting/testing/building equipment etc to do a dead time test on this project - it's way easier for me to farm it out and get it close.

Since I'm using MSExtra 2 (and not 3 which appears to allow you to plot out the entire curve) should I just get it tested at one voltage (13.2) and then enter that figure in and be done with it or do I need to test it at more then one voltage?

[jsmcortina]

I just can't spend the time plotting/testing/building equipment etc to do a dead time test on this project - it's way easier for me to farm it out and get it close.

It only takes an hour or so!

James

[ErnieJones]

I just can't spend the time plotting/testing/building equipment etc to do a dead time test on this project - it's way easier for me to farm it out and get it close.

It only takes an hour or so!

James

Hahaha - I've already got a vein popping out of my forehead Thanks for the encouragement though

If I sent the injector out what would I have to tell them? Do the flow test at 13.2 volts and calculate the dead time at the same voltage? Do I need to get them to also test it at another voltage? Bear in mind, I'm using MSExtra 2 so I can't add in all the detail that can apparently be done with MsExtra3.

[LAV1000]

Let them also test at a lower voltage (12V).
This way you can caculate msec/V for each injector.
If you didn't know, voltage has a effect on deadtime.
Lower voltage > higher deadtime.

[ErnieJones]

Let them also test at a lower voltage (12V).
This way you can caculate msec/V for each injector.
If you didn't know, voltage has a effect on deadtime.
Lower voltage > higher deadtime.

It's best to assume I don't, that way, you'll only get pleasant surprises

OK, so I need them to flow test the injector at 13.2 and do a dead time test at both 13.2 and 12V ?

The reason why I keep trying to nail this down is that I have to send the injector to another country so it would really suck if it came back and I didn't get them to test all the things I should have.

[LAV1000]

OK, so I need them to flow test the injector at 13.2 and do a dead time test at both 13.2 and 12V ?


Yes

[ErnieJones]

Let them also test at a lower voltage (12V).
This way you can caculate msec/V for each injector.
If you didn't know, voltage has a effect on deadtime.
Lower voltage > higher deadtime.

OK, I got the injectors back from Fuel Injector Clinic along with a datasheet. For the injector I'll be using they came up with these figures;

13.2v offset = 496

So I entered that value in the Injector Dead Time field (.496)

I also had them test it at 12v (as you recommended) and they came up with an offset of 576

With that information, how do I come up with a value for Battery Voltage Correction(ms/v) ?

[Yves]

.576-.496 = 0.08 ms for 1.2 V difference, which in my book is 0.066ms/V. Low figure. I got 0.100 in the range of 12.2-13.2-14.2V. A lot more with lower voltages, like .266

[ErnieJones]

OK, so you just take the 12V offset and subtract it from the 13.2v offset;

12v Offset (MS) is .576 - 13.2v Offset (MS) is .496
Subtract the two and you get 0.08 ms difference...

The voltage difference between the two test points (13.2 & 12) = 1.2
How do you come up with the figure 0.066ms/V ?

Hang on.... we need a value for ms/v so .08 ms / 1.2 = 0.066666