another DBW Idle problem

[Niek]

Hi,

My name is Niek Loog and I study at the HTS Autotechniek in Arnhem in the Netherlands (Automotive engineering). My task here is to get a 2007 Impreza WRX STi Prodrvive running on hydrogen.
A MoTeC M800 ECU was fitted and the tanks are filled with CNG, I didn't fill them with hydrogen yet because I want to affirm that the system is completely safe for running on hydrogen. Now my problem is that I don't get a lower RPM than 950. I don't know if the ECU file helps but I added it anyway.

[figgie]

Well.

How was the dbw setup initially? Have any tables for tp v tpd that you can adjust limits?

[MarkMc]

Hello Niek,
The throttle translation table is set so that 2% is the minimum throttle position. The idle control is more or less turned off in this file (no P, I or D settings), you should leave this off for now.

Go the "Adjust"-"Functions"-"Drive by Wire"-"Position Translation". Thsi table sets the relationship between the drivers pedal (TPD) and the actual throttle butterfly position, if you look at the first table value it says that when the throttle pedal is at 0% make the throttle butterfly position 2%, if you lower this number the idle will come down.

Just remember that idle quality is very dependant on the fuel and ignition tables, your tables look a little bit "untuned" so you may need to work with these two table to get the idle lower and steady.

[Niek]

thanks a lot!
I set the throttle translation table to 0%, it helped a bit but it still isn't shutting the butterfly completely.
Could it be that I have to calibrate the closed position of the butterfly?

And I would like to know what kind of things all influence the Idle program. Is there maybe a file where I can find all those things in?

[Niek]

the problem was solved by pushing the butterfly to it's fully closed position to calibrate the lowest point

[IJ.]

the problem was solved by pushing the butterfly to it's fully closed position to calibrate the lowest point

You normally set 0 with a 10 thou feeler gauge between the butterfly and throttle body, the butterfly defaults to party open and this gives a fast enough idle speed to limp home if needed.

[MarkMc]

The Closed throttle positions should always be set with the butterfly pushed all the way to the mechanical stop, you do not need to force it. The base idle throttle position is then set in the Throttle Translation table.

[IJ.]

The Closed throttle positions should always be set with the butterfly pushed all the way to the mechanical stop, you do not need to force it. The base idle throttle position is then set in the Throttle Translation table.

That conflicts with page #9 of the DBW4 manual Mark?
(what I based my post on)

[MarkMc]

Yes,
The DBW4 manual needs to be updated. The completly correct way is as I stated above, I think Originally we made a consession to people who could not handle the fact that their throttle position did not go to 0% when they got their foot off the throttle.

Either way will not be a problem really but unfortunately when you say 0.5mm people stress that 0.3mm may make the engine blow up. And as you can understand 0.5mm on which engine? Obviously the original reason for this post.

[IJ.]

Thanks for the update Mark!
(I did question it at the time)

I'll do it your way from now on!