idle derivative airflow tables/lookup

[WS6FirebirdTA00]

Not really sure on how the idle derivative ratio is determined, as far as where it puts you in the high and low rpm tables.

Also, I am a little unclear on the slow and fast filter values and the adjustment on them.

Pretty much, I am trying to play with some issues I have when the motor is slowing in speed. I want it to start to add air sooner to prevent dipping, and also set it so it does not over correct and shoot the rpms up.

[JakeFusion]

No one ever responded here? I was going to play with this but wanted to see what some guidelines were...

[WS6FirebirdTA00]

I played a lot with the PID controls on mine trying to get it to idle well with the light flywheel. When I mean idle well, dip is not acceptable. I want to throw in the clutch, cut a turn and have it be as smooth as can be.

The derivative airflow, or the derivative control in any PID system, is fast acting. I did not get any answer on the ratio to put a good explanation to it. The only thing I gather on the filters is based on the rate of change it will make this more or less responsive.

Honestly, I don't like to mess with derivative control a whole lot in any PID system unless I have to. I did add some to the higher fast/slow ratio value, but that was it. I controlled the rest through throttle cracker, follower, and the PI settings. In different OSs they have different controls - which is not only a total pain in the ass, but make you have to tune a little different based on the OS when running into idle problems.

On my 2000 OS, I can actually get into adaptive idle conditions rolling. So I played a lot with my adaptive spark setting to help. If I used the 2002 OS, I was screwed. I got so fed up having to reinvent the wheel I just stuck with the 2000 OS. In the 2000 OS I could not have any throttle cracker airflow, in the 2002 I had to. There are still a lot of unknowns to me on why this goes on. I also have some strange stuff on mine where adaptive airflow numbers jump far negative after a start and I can't find any explanation. I posted and discussed with some of the HPT guys but we could not draw any conclusions.

Are you trying to do something specific with this or just playing around?

[dermotw]

Interesting, I have spent lots of time also trying (and only half succeeding) to get my car (light flywheel, blah blah, see the sig...) to idle without odd dips, or also peaks when maneuvering at low speed (parking etc.). I have changed so many things so many times that I don't think I can recall it all! ('99 pcm btw). It's passable now, but the hours I've spent....

-D