Injector deadtime value spreadsheet

[gunni]

Hello all.

I know most of us have done the deed of properly getting correct deadtime values for setups, however I as many haven´t actually recorded those values for future use.
So I have made this spreadsheet that incorporates the required values. feel free to edit as you wish and share with any VEMS user. Only fill in the section that applies to your setup.

See this file - https://onedrive.live.com/redir?resid=CDCE02FA96C1B409!374550&authkey=!AGfKoQMkhN8joBk&ithint=file%2cxlsx

[boostd audi]

great work gunni

[dnb]

Good idea. 

I have just made myself an injector test bench using a spare VEMS and various spare parts I had cluttering up the workshop.  It should enable me to clean injectors, calculate dead times and any flow deviations between sets of injectors.  I will post the results of the various injectors I have here once I am happy it all works properly.

[Kamuto]

Good idea. 

I have just made myself an injector test bench using a spare VEMS and various spare parts I had cluttering up the workshop.  It should enable me to clean injectors, calculate dead times and any flow deviations between sets of injectors.  I will post the results of the various injectors I have here once I am happy it all works properly.

I would like one feature in vems, like injector test where you can say how many injections and what pulsewidth vems must do

[dnb]

Does the terminal input over rs232 still work?

[Kamuto]

Does the terminal input over rs232 still work?

I believe yes

[dnb]

so doing MDP04 and MDJ00 should set a 4us pulse and fire the first injector.  This could then be wrapped up in a Brayterm script as a test.  It would be nice to have such a facility in VEMSTune.

[boostd audi]

this has a few

http://injector-rehab.com/shop/lag.html

[gunni]

We need VEMS confirmed values from users.

[dnb]

Here is the first test of my injector tester with some spare Siemens Deka injectors.  They are notionally 600cc/min @ 3.5 bar and 13.5v supply.



I have a 3 bar regulator and a power supply that can't quite supply enough current to run the ECU, injectors and fuel pump, so suffered a voltage droop to 11.7v.  That said, the injectors are well matched and over the 3 test runs are linear.  The only oddity is that the intercept on the chart is positive, meaning the injectors apparently are really slow to close (maybe this is a problem with my old VEMS ECU?).  This will make short pulsewidths difficult to control with these injectors.  I should now be able to derive a very good set of correction parameters for the ECU based on these tests at a set of different voltages.

I will repeat the tests with a few more data points when I have a better power supply.

[fphil]

This is a much interesting topic. Indeed it is really a pain to know the true specs of the injectors  on the market in order to choose the good model (dimensions, flow, spray pattern) and next to be able to well tune the ECU.

I found full specs of some Siemens / Continental VDO Deka VII injector  which can be useful here
http://www.usa.vdo.com/generator/www/us/en/vdo/main/hidden/downloads/downloads_en.html
In particular there are some curves for flow and Voltage sensitivity.

But too bad these racing injectors are too big for my need, so thank you if someone knows references for some modern injector as  Bosch EV14EL or DekaVII (long type, dual cone and delta 0°) about 300cc/min and EV1 connector

[dnb]

I have done a bit more work on my test rig.  I have a much bigger power supply and have fitted a 30v flyback to my (very old) test ECU.  This has improved things significantly (test done at 3bar rail pressure and 14.0v injector power supply):



The close time of the injector is now much quicker than the open time as one would expect.  I can now use the data to derive some calibration parameters:

The injector size is the gradient of the linear region of the above chart.  Converted to the usual units this is 583cc/min.
The "simple" dead time is the value of pulsewidth when flow is zero.  In this case, this is 307.4us.

The injectors won't operate linearly below about 2ms.  Therefore if the ECU is calling for pulsewidths less than this (for example at idle) the results will be extremely poor.  The simple calibration scheme can't get around this. 

Obviously more tests are needed for other supply voltages.  If the simple model is accurate, the gradient does not change with voltage.  I am still working on deriving values for the "standard" injector model.

[gunni]

Hi do you have the values so I can put them in the spreadsheet?

[dnb]

The "simple" model looks something like this for my small injectors:

Code Select Expand


Part number:  0 280 155 931
Assessed size at 3 bar pressure:  259.0cc/min

10v   610.1us
12v   286.5us
14v   52.3us
16v   -129.1us

Note that the negative 16v offset cannot be used.  It is due to the closing time of these injectors being slower than the opening at this supply voltage.  This value should be set to zero.

My larger set of injectors have tested (so far) as follows:

Code Select Expand

Siemens DEKA nominal 600cc injectors
Assessed size at 3 bar pressure:  583.3cc/min

8v    864.4us
10v  688.0us
12v  512.1us
14v  307.3us
16v  144us

This is within 20us of the values calculated from the injector data sheet supplied with the injectors.

[gunni]

part number on the Deka?

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