G4X Supra Plugin DBW Tracking issues

[DanielCPG]

Hello.

Currently have a Supra with a G4X plugin i have tuned. I am having an issue only at idle. It seems the throttle plate cannot achieve the target and constantly undershoots/then overshoots.

I have spoken to simon and he explained its probably fighting the spring in this position. I have tried to use the feed forward table.

Increasing the I to 0.145 makes it worse. .080 makes helps. but doesnt completely alleviate it. Sometimes it will track and land ok. But sometimes it will hunt. I cant always replicate it.

I have also tried 50 on the D

and i have increased and decreased the  P, but i cant overcome it.

Any input would be great

here is a log with the I at 0.145. you can see it over shoots and undershoots, but eventually settles. this is an example where it does settle, however i have had circumstances where it ends in an endless loop of undershoot/overshoot.

Supra tune.pclx Supra log export.llgx

[Adamw]

What is the throttle body?

[DanielCPG]

Genuine Bosch Motorsports 82mm Electronic Throttle Body (ETB) - 0 280 750 473

[Adamw]

I have seen something similar before, some of the Bosch throttles seem to have quite a heavy stiction effect where you see the motor duty cycle slowly build by about 30% with no TPS movement then you will get a big jump in position and it will slowly wind down again.  I've never been sure if it is due to damaged gears or some other mounting orientation issue or something as not all of them seem to suffer from it.  Its also not often around the spring balance point so feed forward doesnt really help in that case.  

Higher than normal derivative gain to create some faint noise will usually fix this.  Try it up around 80, you may also need to increase P a little further with the extra derivative.