VEMS Community Forum
Technical => Fuel Injection => Topic started by: gunni on February 14, 2016, 08:15:19 pm
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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
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great work gunni
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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.
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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
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Does the terminal input over rs232 still work?
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Does the terminal input over rs232 still work?
I believe yes
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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.
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this has a few
http://injector-rehab.com/shop/lag.html (http://injector-rehab.com/shop/lag.html)
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We need VEMS confirmed values from users.
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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.
(https://dl.dropboxusercontent.com/u/8968424/inject.jpg)
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.
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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
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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):
(https://dl.dropboxusercontent.com/u/8968424/inject2.jpg)
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.
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Hi do you have the values so I can put them in the spreadsheet?
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The "simple" model looks something like this for my small injectors:
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:
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.
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part number on the Deka?
List updated
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No readable part number on the Dekas.
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Are the Siemens these? http://www.siemensdekafuelinjectors.com/60-lb-hr-siemens-deka-fuel-injectors-high-impedance-long-style-ev1-connector/ (http://www.siemensdekafuelinjectors.com/60-lb-hr-siemens-deka-fuel-injectors-high-impedance-long-style-ev1-connector/)
The "simple" model looks something like this for my small injectors:
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:
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.
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Not those. Mine are the shorter, fatter ones. I think they're supposed to be 57lbs/hr and are a fair number of years old now.
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Most popular siemens are 60 and 80 here
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Does anyone have injector settings for Siemens deka 870cc 80lb 110324 injector from vems webshop.
And can 870cc work good for emmision test on idle on 6cylinder 2.0 engine.
My current PW is 1.4ms
https://shop.vems.hu/catalog/siemens-870cc-80lb-injector-p-136.html (https://shop.vems.hu/catalog/siemens-870cc-80lb-injector-p-136.html)
(http://i.imgur.com/gwF1VLx.jpg)
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My Deka injectors go non-linear below about 2ms pulselength. At best this will make your VE table look weird at idle and at worst the idle will be very bad and emissions will be suspect since the injectors don't do the same thing from pulse to pulse.
It's easier to tune if you can get the idle to require more than 2ms pulses (eg smaller injectors) but I have found my Deka injectors injected a repeatable amount of fuel even in the non-linear region so you have a good chance of making it work.
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The 60# injectors I posted above run at ~1.4-1.6ms at idle. I can't say whether they're linear or not but the idle is solid and somewhat reasonable to tune. There're definitely fluctuations in lambda not seen anywhere else at idle so maybe they're similar in behavior to your 57#ers.
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The VDO specs of the DekaVII injectors give the min operating PW at 2% linear error (see the link above). Per example it is 1.2ms for the FI14326 46 lb/hr.
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Here are deka 4 IV high impedance , looks like minimum PW for them is 1.7... my car idles at 1.4 with them :'(
(http://i.imgur.com/Iza1ZHE.jpg)
(http://i.imgur.com/pckPI7Z.jpg)
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Can you put your injector settings for them into the spreadsheet?
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Can you put your injector settings for them into the spreadsheet?
I will after i test the settings...
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(http://i.imgur.com/6OwZKSC.png)(http://i.imgur.com/C4tV8Y2.png)
After changing siemens deka 4 80lb / 870cc injector setting from traditional ( recomended settings from forum)
to simplified setting values from injector PDF i got VE idle from 48 (old settings) to 34. PW is same as before 1.4ms.
Injector deadtime table is injector voltage offset??
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"PW is same as before 1.4ms."
It has to be so, no?
"Injector deadtime table is injector voltage offset??"
I believe it is the PW(ms) offset of the regression line of the characteristic injector flow curve, Flow(cc/min) versus PW(ms). for a some Voltage
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(http://i.imgur.com/6OwZKSC.png)(http://i.imgur.com/C4tV8Y2.png)
After changing siemens deka 4 80lb / 870cc injector setting from traditional ( recomended settings from forum)
to simplified setting values from injector PDF i got VE idle from 48 (old settings) to 34. PW is same as before 1.4ms.
Injector deadtime table is injector voltage offset??
Which are the ones that work correctly for your injectors?
1.4ms is the total time so that will always be the same for the same idle airflow no matter your VE values as your deadtime values will have been changed.
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I removed 870cc siemens injectors and went back to stock injectors, they were too big for 2.0 v6 engine 800rpm idle, it was too low PW on idle, it worked but not 100% smooth on idle.
I suppose they would work gread on 3.0 6-cyl on 2.0 4 cyl engine...
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Iv got this table with new injectors but i dont know what values i have to put to vems?
(https://s21.postimg.org/mdc0ad9fb/80_LB.jpg)
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I have to calibrate a set of Bosch EV14 injectors, that is at minimum the eadtime as function of voltage, and the discrepency of their flow rate.
Of course the best for doing so is to have an injector bench which is expensive to buy and not easy or time consuming to build.
Besides Gunni has shown us a simple way which lets find the dead time on the car using the lambda.
I am thinking of another way which could be equally easy to perform: The dead time should be close the lowest PW for which there is still a spray.
This threshold could be easy to get using the injector testing mode of VT but on the condition of an upgrade of this function which will allow to enter the length of the test pulse.
What do you think?