That's what the PID disable RPMdot is for. It disables PID if RPMdot spikes over a certain value. It was added specifically for the situation you describe.
I was asking about the gslender neutral switch interlock. Scenario:
Car stopped, Idling in neutral, CL idle active
Disengage the clutch
Put the car in gear (activating the neutral interlock), without touching the throttle, clutch still disengaged
Will the simple act of putting the car in gear (but engine still spinning freely) kick up the idle speed to i-v-t? I also use an IAC close delay of zero (don't use that feature) if that changes anything.
Greg G wrote:
pmbrunelle wrote:From a throttle lift, if we have say 10 degrees of spark retard from the nominal idle timing, that will make the IAC return to its normal position (with normal spark timing) take longer, as the RPM error will be low. CL idle will only be able to reduce the number of steps as AIA slowly returns to zero correction. In the meantime, we're stuck with an inefficient idle - lots of idle air, but little advance. We even see that in your datalog to an extent - lots of idle duty change with little corresponding change in RPM.
From throttle lift- it will go to the duty commanded in IVT, and start moving only when CL idle entry conditions are met. So the AIA gets the RPM close to target, avoiding a large step from the idle valve on CL entry. Yes, AIA is still reactive (though much faster than the idle valve). I do agree that a revised dashpot action would help immensely.
Regarding my graph above- which parts show the inefficient idle? The idle valve spikes come from the battery voltage correction, and the plateaus come from the dashpot/IVT/AC adder. This was taken with the car in neutral, free revving. So yeah, my goal was to make RPM not change much. But if there's room for improvement, I'm all for it!
I wasn't talking about the spikes, but idle immediately after a throttle lift. We can tell it's fuel inefficient - lots of idle air (compared to once we're idling in closed-loop at the target, in equilibrium) is required to maintain that idle, because of the spark retard from the AIA. MAP is also high during that period. MAP normally increases as we reduce idle speed - here as we "ramp down" the idle, MAP is decreasing. The MAP being high at the "high" idle after lifting is an indicator of excess spark retard. Manifold pressure is a good indicator of efficiency at idle. That's why we generally tune idle timing to maximize vacuum.
gslender wrote:pmbrunelle, why not post some graphs and examples after using the 2.2b mod to show where you think it needs further improvement ??
I haven't used any of your firmwares besides 3.2.1 release. And my car is sleeping for the winter until the snow is gone. Anyway, these are ideas of mine that I'm implementing on my car no matter what in the spring - I figured I'd share my ideas with the community, and if they were to be integrated the releases, it would be less patching for me to do come springtime. So there won't be any datalogs with your straight 2.2 firmware.
However, I do have old datalogs demonstrating the effects of idle spark timing on fuel efficiency, which I will post shortly.