changing injector dead time, what about VE?
05-21-2015, 12:59 PM
#21
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Join Date: Sep 2010
Location: Belgium
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This will sound corny, but: it's really about creating harmony between ALL the settings to get a good idle. Then it's about smoothing everything over and dialing in enough correction and buffer zone such that extremes (high power load, cold temps, ac kicking in, fans kicking in, etc) don't disrupt the idle and are compensated for timely and efficiently.
You need proper afr
You need proper timing
You need to pay attention to the cells AROUND both those areas too, they affect it
You need to do idle valve test to determine iacv range
You need to tune CL idle control settings, PID, and dashpots
You need proper AIT compensation
You need proper EGO correction settings
There's probably more I'm forgetting
A lot of this stuff gets overlooked
You need proper afr
You need proper timing
You need to pay attention to the cells AROUND both those areas too, they affect it
You need to do idle valve test to determine iacv range
You need to tune CL idle control settings, PID, and dashpots
You need proper AIT compensation
You need proper EGO correction settings
There's probably more I'm forgetting
A lot of this stuff gets overlooked
rpm is stable enough in my opinion but it's the vibration I want to get rid of...
I will post a log when idling, maybe you guys notice something wrong.
Thanks
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05-24-2015, 11:13 PM
#24
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Join Date: May 2015
Posts: 86
Total Cats: 11
My experience with the 1.6 is that it's sensitive to injection timing at idle. You can smooth it out by changing end of injection timing in the idle area if you are sequential. Since you are batch fired you don't have that option.
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01-05-2016, 08:58 AM
#32
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Join Date: Sep 2015
Posts: 20
Total Cats: -21
The fueling calculation is as follows:
PW = DT + (ReqFuel * MAP * VE[RPM,MAP] * AirDen * BaroCor * corrections)
Forget the corrections and we get:
PW = DT + (ReqFuel * MAP * VE)
Rearange the formula to find VE:
VE = (PW - DT)/(ReqFuel*MAP)
Assume we have 265cc injectors and a deadtime of 0.8ms, a required fuel value of 5.51 and want to find the PW at 80kPa with a VE of 55%:
PW = DT + (ReqFuel * MAP * VE)
PW = 0.8 + (5.51 * 0.80 * 0.55)
PW = 3.2244 m/s
We can rearrange to find VE as below:
VE = (PW - DT)/(ReqFuel*MAP)
VE = (3.2244 - 0.8) / 5.51 * 0.80)
VE = 0.55
Re scaling for new injectors example:
We upgrade to blue 540cc injectors, an assume a Required Fuel value of 2.25, and a dead time of 0.95
If we want to re-scale the VE table for new injectors we first solve to find the current PW (3.2244m/s in our example).
Then find the correction factor for the new injector. In our example using 265cc and 540cc injectors:
Correction factor = Old Injector cc min / New Injector cc min
Correction factor = 265 / 540
Correction factor = 0.4907
Applying this correction factor we find the new pulse width:
New PW = Current PW * Correction Factor
New PW = 1.58 m/s
Then we calculate the NEW VE value to populate our VE table as below:
New VE = (New PW - New DT)/(New ReqFuel * MAP)
NEW VE = (1.58 - 0.95) / (2.25 * 0.80)
New VE = 0.35 or 35%
PW = DT + (ReqFuel * MAP * VE[RPM,MAP] * AirDen * BaroCor * corrections)
Forget the corrections and we get:
PW = DT + (ReqFuel * MAP * VE)
Rearange the formula to find VE:
VE = (PW - DT)/(ReqFuel*MAP)
Assume we have 265cc injectors and a deadtime of 0.8ms, a required fuel value of 5.51 and want to find the PW at 80kPa with a VE of 55%:
PW = DT + (ReqFuel * MAP * VE)
PW = 0.8 + (5.51 * 0.80 * 0.55)
PW = 3.2244 m/s
We can rearrange to find VE as below:
VE = (PW - DT)/(ReqFuel*MAP)
VE = (3.2244 - 0.8) / 5.51 * 0.80)
VE = 0.55
Re scaling for new injectors example:
We upgrade to blue 540cc injectors, an assume a Required Fuel value of 2.25, and a dead time of 0.95
If we want to re-scale the VE table for new injectors we first solve to find the current PW (3.2244m/s in our example).
Then find the correction factor for the new injector. In our example using 265cc and 540cc injectors:
Correction factor = Old Injector cc min / New Injector cc min
Correction factor = 265 / 540
Correction factor = 0.4907
Applying this correction factor we find the new pulse width:
New PW = Current PW * Correction Factor
New PW = 1.58 m/s
Then we calculate the NEW VE value to populate our VE table as below:
New VE = (New PW - New DT)/(New ReqFuel * MAP)
NEW VE = (1.58 - 0.95) / (2.25 * 0.80)
New VE = 0.35 or 35%
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03-22-2018, 05:49 AM
#33
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Join Date: Apr 2014
Posts: 3
Total Cats: 2
The fueling calculation is as follows:
PW = DT + (ReqFuel * MAP * VE[RPM,MAP] * AirDen * BaroCor * corrections)
Forget the corrections and we get:
PW = DT + (ReqFuel * MAP * VE)
Rearange the formula to find VE:
VE = (PW - DT)/(ReqFuel*MAP)
Assume we have 265cc injectors and a deadtime of 0.8ms, a required fuel value of 5.51 and want to find the PW at 80kPa with a VE of 55%:
PW = DT + (ReqFuel * MAP * VE)
PW = 0.8 + (5.51 * 0.80 * 0.55)
PW = 3.2244 m/s
We can rearrange to find VE as below:
VE = (PW - DT)/(ReqFuel*MAP)
VE = (3.2244 - 0.8) / 5.51 * 0.80)
VE = 0.55
Re scaling for new injectors example:
We upgrade to blue 540cc injectors, an assume a Required Fuel value of 2.25, and a dead time of 0.95
If we want to re-scale the VE table for new injectors we first solve to find the current PW (3.2244m/s in our example).
Then find the correction factor for the new injector. In our example using 265cc and 540cc injectors:
Correction factor = Old Injector cc min / New Injector cc min
Correction factor = 265 / 540
Correction factor = 0.4907
Applying this correction factor we find the new pulse width:
New PW = Current PW * Correction Factor
New PW = 1.58 m/s
Then we calculate the NEW VE value to populate our VE table as below:
New VE = (New PW - New DT)/(New ReqFuel * MAP)
NEW VE = (1.58 - 0.95) / (2.25 * 0.80)
New VE = 0.35 or 35%
PW = DT + (ReqFuel * MAP * VE[RPM,MAP] * AirDen * BaroCor * corrections)
Forget the corrections and we get:
PW = DT + (ReqFuel * MAP * VE)
Rearange the formula to find VE:
VE = (PW - DT)/(ReqFuel*MAP)
Assume we have 265cc injectors and a deadtime of 0.8ms, a required fuel value of 5.51 and want to find the PW at 80kPa with a VE of 55%:
PW = DT + (ReqFuel * MAP * VE)
PW = 0.8 + (5.51 * 0.80 * 0.55)
PW = 3.2244 m/s
We can rearrange to find VE as below:
VE = (PW - DT)/(ReqFuel*MAP)
VE = (3.2244 - 0.8) / 5.51 * 0.80)
VE = 0.55
Re scaling for new injectors example:
We upgrade to blue 540cc injectors, an assume a Required Fuel value of 2.25, and a dead time of 0.95
If we want to re-scale the VE table for new injectors we first solve to find the current PW (3.2244m/s in our example).
Then find the correction factor for the new injector. In our example using 265cc and 540cc injectors:
Correction factor = Old Injector cc min / New Injector cc min
Correction factor = 265 / 540
Correction factor = 0.4907
Applying this correction factor we find the new pulse width:
New PW = Current PW * Correction Factor
New PW = 1.58 m/s
Then we calculate the NEW VE value to populate our VE table as below:
New VE = (New PW - New DT)/(New ReqFuel * MAP)
NEW VE = (1.58 - 0.95) / (2.25 * 0.80)
New VE = 0.35 or 35%
Some more stuff. I have too much time on my hands at present!
I have had the wrong dead time in my MSQ for nearly 3 years. RX8 injectors. I had dead time set at 1mS. When I changed it to a "better" value of .8mS idle would go stupid lean. Not wanting to retune the whole VE, I had until now decided to just leave it at 1mS and live with it.
BUT...
You can use this spreadsheet that I've designed to recalibrate the VE table. I tried it, seems to work fine at idle, (the worst scenario, low pulse width). I still have to VEAL higher Pulse widths, but I think they should be pretty close hopefully. Use at your own risk, and if you don't understand why you might need it then don't use it.
https://drive.google.com/open?id=1lTiwZ ... uT4rBK2EhD
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03-22-2018, 06:38 AM
#34
Newb
Join Date: Apr 2014
Posts: 3
Total Cats: 2
Some more stuff. I have too much time on my hands at present!
I have had the wrong dead time in my MSQ for nearly 3 years. RX8 injectors. I had dead time set at 1mS. When I changed it to a "better" value of .8mS idle would go stupid lean. Not wanting to retune the whole VE, I had until now decided to just leave it at 1mS and live with it.
BUT...
You can use this spreadsheet that I've designed to recalibrate the VE table. I tried it, seems to work fine at idle, (the worst scenario, low pulse width). I still have to VEAL higher Pulse widths, but I think they should be pretty close hopefully. Use at your own risk, and if you don't understand why you might need it then don't use it.
https://drive.google.com/open?id=1lTiwZ ... uT4rBK2EhD
I have had the wrong dead time in my MSQ for nearly 3 years. RX8 injectors. I had dead time set at 1mS. When I changed it to a "better" value of .8mS idle would go stupid lean. Not wanting to retune the whole VE, I had until now decided to just leave it at 1mS and live with it.
BUT...
You can use this spreadsheet that I've designed to recalibrate the VE table. I tried it, seems to work fine at idle, (the worst scenario, low pulse width). I still have to VEAL higher Pulse widths, but I think they should be pretty close hopefully. Use at your own risk, and if you don't understand why you might need it then don't use it.
https://drive.google.com/open?id=1lTiwZ ... uT4rBK2EhD
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