lulu2003
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« Reply #15 on: August 23, 2012, 09:43:28 AM »
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no, sorry, you are wrong!
please, simply read it in the Funktionsrahmen section LDRPID under Applikationshinweise:
the application of that map will be done at full throttle(!) and modifiying the 2 variables WGDC and rpm and reading the resulting boost.
it reflects how linear boost and WGDC are coupled (in order to make the PID controller work best).
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nyet
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« Reply #16 on: August 23, 2012, 09:53:07 AM »
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WG behavior is a function of the actuator spring and exhaust backpressure.
WG "behavior" isn't being properly defined here. The question is how the boost responds to the DC. It is not a linear relationship. PIDs assume their output results in a linear response when fed back into the system. I.e. 2x more WG does not result in 2x boost throughout every WG, boost, flow, backpressure etc. operating point. |
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lulu2003
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« Reply #17 on: August 23, 2012, 11:41:47 AM »
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true, I was a bit more precise in my last post.
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prj
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« Reply #18 on: August 23, 2012, 01:11:11 PM »
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no, sorry, you are wrong!
please, simply read it in the Funktionsrahmen section LDRPID under Applikationshinweise:
the application of that map will be done at full throttle(!) and modifiying the 2 variables WGDC and rpm and reading the resulting boost.
it reflects how linear boost and WGDC are coupled (in order to make the PID controller work best). Yes, it is done at full throttle, but at fixed WGDC. I am talking about the entire LDRPID. The linearization (KFLDIMX and KFLDRL together) basically tells the ECU how much WGDC should be given for a given boost level. There is no direct relation to the throttle, it is indirect through boost request. |
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nyet
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« Reply #19 on: August 23, 2012, 01:20:03 PM »
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The linearization (KFLDIMX and KFLDRL together) basically tells the ECU how much WGDC should be given for a given boost level.
There is no direct relation to the throttle, it is indirect through boost request.
LDIMX is the integral limit, which caps the steady state (static) PRE-linearized WGDC. This is because in the steady state, lde is zero and unchanging (P and D factors are zero), so the only contribution is I. WGDC is then adjusted by LDRL to result in the actual DC sent to the N75. Not only is it indirect to throttle, it is also indirect to boost request. It is "direct" only in the sense that it it comes from lde, and even that is indirect. The only "direct" effect is through LDRL and LDIMX (in steady state), and RPM in both those maps. |
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prj
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« Reply #20 on: August 23, 2012, 02:25:47 PM »
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I agree nyet, but it also makes sense to look at the big picture instead of fixating on a single map or constant  |
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lulu2003
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« Reply #21 on: August 24, 2012, 03:18:05 AM »
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Yes, it is done at full throttle, but at fixed WGDC.
I am talking about the entire LDRPID. The linearization (KFLDIMX and KFLDRL together) basically tells the ECU how much WGDC should be given for a given boost level.
There is no direct relation to the throttle, it is indirect through boost request.
is it so hard for you to agree that your assumption was incorrect? prj, we are talking about that single linarisation map all the time. you wrote: Because it[the map KFLDRL] tells the ECU how much base WGDC to request to reach target... And this is defined by throttle plate angle and RPM.
It has been this way for over 15 years in Bosch engine management as well which is still completely incorrect. and nyet an me explained several times why.... |
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prj
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« Reply #22 on: August 24, 2012, 03:29:44 AM »
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is it so hard for you to agree that your assumption was incorrect?
prj, we are talking about that single linarisation map all the time.
you wrote:
which is still completely incorrect. and nyet an me explained several times why....
You read things like you want, and you can add things to my text which I did not say. Maybe it could be worded better, but my idea was from the start, that KFLDIMX and KFLDRL among others tell the ECU how to reach target boost. And this is defined by plate angle and RPM. To be honest, you should really be tuning things instead of trying to nitpick. I spent the evening yesterday linearizing LDRPID on a big turbo car for example per the FR. I know perfectly how it works. The outcome out of that map is still basically "base DC", because the objective of it is to make the car's mechanical pressure control system seem like a straight line to the PID. |
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« Last Edit: August 24, 2012, 03:33:06 AM by prj »
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lulu2003
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« Reply #23 on: August 24, 2012, 03:36:23 AM »
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now you got it! But I am still curious how you manage to "linearizing LDRPID on a big turbo car for example per the FR"  |
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prj
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« Reply #24 on: August 24, 2012, 05:27:53 AM »
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now you got it! But I am still curious how you manage to "linearizing LDRPID on a big turbo car for example per the FR" Because tuning is not only editing the last column of a map. So if you want ECU to still properly control boost at part throttle, you have to linearize the PID. Even if at WOT you run fixed duty. |
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bbernd
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« Reply #25 on: November 13, 2012, 05:12:33 AM »
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Yes, it is done at full throttle, but at fixed WGDC.
I am talking about the entire LDRPID. The linearization (KFLDIMX and KFLDRL together) basically tells the ECU how much WGDC should be given for a given boost level.
There is no direct relation to the throttle, it is indirect through boost request.
Why is the AXIS for relative boost request only up to 1000 mbar??? (in KFLDIMX)... what is going on for 1300 mbar boost request?? |
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prj
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« Reply #26 on: November 13, 2012, 05:55:26 AM »
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Why is the AXIS for relative boost request only up to 1000 mbar??? (in KFLDIMX)... what is going on for 1300 mbar boost request??
Exactly the same as every other map in the ECU. Last column is read for everything higher. |
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olo
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« Reply #27 on: November 13, 2012, 06:46:23 AM »
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Why is the AXIS for relative boost request only up to 1000 mbar??? (in KFLDIMX)... what is going on for 1300 mbar boost request??
Because input for KFLDIMX is not direct boost request, there is (plsol_w - plgrus_w), depend on CWLDIMX. |
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bbernd
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« Reply #28 on: November 13, 2012, 07:08:42 AM »
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Exactly the same as every other map in the ECU. Last column is read for everything higher.
this is true... but how do you set a Dutycycle for 1500 mbar?? |
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prj
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« Reply #29 on: November 13, 2012, 09:06:07 AM »
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this is true... but how do you set a Dutycycle for 1500 mbar?? Exactly the same way as everywhere else in the ECU when an axis value is higher. Either you set the same duty cycle for everything of 1300 mbar or above or you rescale the axis. |
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