rwyatt365

Okay, I'm street tuning my newly rebuilt engine and things are going well enough. Only there's one thing that is driving me a little bit crazy. At the onset of entering CL idle, just before the Idle correction steps in to keep the idle RPMs at the target, the Idle Duty pops up from the closed value to a (seemingly arbitrary) value of about 39% - the exact value varies slightly, but it's usually between 38 and 40%. Once the CL idle correction starts in, the idle duty will drop down to a stable value and the RPMs come at or near to the target. This behavior is consistent whenever the engine enters into the idle state; jump from the closed position up to 39-ish%, hang there and then drop down to the level to hold the idle target.

Datalog snippet;

It's not that this is causing a drivability issue, it's more of an "aesthetic thing" for when I'm looking at a datalog. I see it and I think "What the hell is making it do THAT?!"

Tune Attached

Zaphod

You have a dashpot adder of 5.5 and your initial value table is ~34 - so there is your 39-40 for when you lift the throttle- could this be your answer?

rwyatt365

Dashpot adder...DOH! That was a hold-over from my ms2 tune. I forgot all about that.

Thanks. I'll remove it and log again today.

rwyatt365

That did the trick! Thanks for the tip Zaphod. I had to bump up my CL Initial Values a bit to "compensate" for what the Dashpot was doing.

Zaphod

Perfect!