VEMS Community Forum
VEMS => Calibration & Mapping => Topic started by: gunni on March 10, 2014, 10:17:56 pm
-
Everything in the fuel calculations requires correct dead time calculations.
Some injectors come with dead time values, but those values may not be relevant to how VEMS uses them. Aside from the fact that you might not know how the injectors where driven during the testing.
Live mapping the dead time is possible and this is how I do it.
1. Warm up engine and get idling as steadily as possible at lambda 1.0
2. Change the lambda target to 0.8 and press BURN
3. If the mixture becomes richer then 0.8 you need longer dead time, if it´s lean then you need shorter dead time so change the value accordingly by 50
4. Put the target back to 1.0 and press BURN
5. Adjust VE map until it idles at 1.0
Go back to step 2 and repeat until changing the lambda target always results in the lambda being the same.
As you get closer to getting correct lambda values all the time make smaller changes.
Why is this important?
The VE table will be more "correct" , all fuel corrections will have the effect they are designed to have. EGO control will be more accurate
and the engine is easier to map on all accounts.
NOTE : When increasing the dead time during this calibration the mixture will become richer so when putting the lambda target back to 1.0 you will need to remove fuel. If you need to lower dead time the mixture will become leaner then 1.0 when target is set back to 1.0, ideally before doing it give the VE map a little bit extra so that the engine doesn´t see higher then 1.1 lambda as it might stall on you.
-
Gunni
If this is using simplified, won't this only give one value in the table (the voltage that this is performed at)? so the other figures would need to be calculated, not sure how this is practically achieved.
If this is using traditional, how do you calculate the the effective rampup as it is only the Injector Voltage Compensation that is changed in this process? (I am assuming that Injector Opening Time @ 13.2v = 0 and Rampup voltage compensation = 4080 as per the help files).
Please clarify.
Thanks
Alex
-
i use lambda 0.9 and 0.8. That give similar power.
If you change lambda from 1.0 to 0.0 for same rpms you will have more vacuum.
-
Gunni
If this is using simplified, won't this only give one value in the table (the voltage that this is performed at)? so the other figures would need to be calculated, not sure how this is practically achieved.
If this is using traditional, how do you calculate the the effective rampup as it is only the Injector Voltage Compensation that is changed in this process? (I am assuming that Injector Opening Time @ 13.2v = 0 and Rampup voltage compensation = 4080 as per the help files).
Please clarify.
Thanks
Alex
This is my question also. Perhaps a bit more info into how VEMS uses the deadtime values would really help also.
Thanks!
-
This is my question also. Perhaps a bit more info into how VEMS uses the deadtime values would really help also.
Have you seen Dave's answer in
http://www.vemssupport.com/forum/index.php/topic,2194.0.html.
Gunni, thanks for the tip. Let's have an automatic tool for that in the wish list!
-
This is my question also. Perhaps a bit more info into how VEMS uses the deadtime values would really help also.
Have you seen Dave's answer in
http://www.vemssupport.com/forum/index.php/topic,2194.0.html.
Gunni, thanks for the tip. Let's have an automatic tool for that in the wish list!
I did not. Thanks for showing me!
I do still wonder how to create a slope for all of the simplified values using the lambda to figure out deadtime values posted above by Gunni...
-
If the injectors had no dead time, the PW would be proportional to lambda (L).
From what I had understood, for some (MAP, RPM), have 2 VE values to get (PW1,L1) and (PW2,L2). Then draw the line trough this 2 points. When that line cross L=0, you get the dead time.
This is a bit theoretical, since this is done for one (MAP,RPM), you should have to take the mean, take care of Voltage, the chosen VE values.
Better to make an Excel sheet or other.
-
added Gunni's deadtime simple setup procedure to help: http://vems.hu/vt/help/v3/v3_injector_settings.html
Best regards, Dave
-
in this calibration process , EGO needs to be off right ?
-
Yes. EGO correction could be added but this is quick and simple enough not to require ECO control
-
also , is this process is eligible for simplified injector dead time table or just for traditional ?
-
I have found the dead times specified for my injectors but im not really sure of what value to use. Deadtimes are specified @ specific voltage, whats best to use for VEMS where i only can enter one?
Precision 1200cc low ohm injectors.
Volts: 8.7v 10.4v 12.2v 13.9v 15.6v 17.4v 19.1v 20.9v
MS: 1.63 1.00 0.80 0.70 0.60 0.56 0.56 0.53
-
There is actually another method, in injector settings change it from traditional to simplified.
then you can input your dead times
-
Ohhh, awesome! Thanks! :D