NefMoto

could someone explain why the KFLDRL map on the 1.8T S3 has 95% values for low rpm then goes back down. I have looked at a couple of other 1.8T files now and none of them do that?

I've check 2 bin's from another S3 8L and a TT mk1 and they do it as well, unless im looking wrong  :-\

My apology, now understand where your looking!

k04 cars spike boost more easily so their control would be different to a k03s

fair enouhg but why the 95% at 760rpm

 ???

because it doesn't matter and the WG would physically stay at 95% because no boost?

Just nice to understand why they would code it like that.  ;D

sort of pre-control and disabling PID in that range of revs??

I am still unsure how the DC linearization table is calculated.

For most files, it seems to be tuned to the effectiveness of the WGDC at various RPM levels... but sometimes it is also used to numb the PID at certain operating points.

The thing that I dont get is why it is RPM related, and not, say, load or airflow or boost related.

Because it 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 :)

But it isn't base DC!

It happens at the very end as a "correction" to the final output of the PID controller... and the "correction" is only RPM based...

you find it here in the forum.
one user calculated that linearisation table completely by testing his Wastegate behaviour.
great work.

It is basically base DC, because it linearizes the wastegate behaviour for the PID controller.
And wastegate behaviour is more or less a function of RPM and Throttle...

I disagree.

WG behavior is a function of the actuator spring and exhaust backpressure.

You are nitpicking. This is a waste of time.

The ECU needs to know how much WGDC it needs for a certain boost pressure level. This boost pressure level WGDC in steady state can be mapped based on RPM and TPS, and then looked up.
This is what the map is for - simple. The fact that there is a PID controller running, and that this map linearizes the wastegate duty for the pid is just a question of interpretation.

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).

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.

true, I was a bit more precise in my last post.

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.

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.

I agree nyet, but it also makes sense to look at the big picture instead of fixating on a single map or constant :)

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.

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"  ;D

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.

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.

Because input for KFLDIMX is not direct boost request, there is (plsol_w - plgrus_w), depend on CWLDIMX.

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.

deleted - I got it  ;D




  

What if you jack the wastegate spring up to say 12 psi? You would need a higher %WGDC earlier in RPM correct?