In decel mode, the ECU seems to turn off "closed-loop feedback controlled" actuation of the throttle body which results in the TPlate% defaulting to the mechanical rest position. But, as soon as you apply even the tiniest bit of TPedal%, the ECU moves this to a position that is lower than the mechanical rest position (overriding the spring).
See the following video of this phenomenon captured during IGN on/Engine off mode.
When you hear the high pitched noise, that is when I manually increase the TPedal% by a very very slight amount that is just enough to activate the ECU's manipulation of the TPlate%. As you can see, the mechanical rest position (no high pitched noise) has a larger TPlate% than a TPedal% of just slightly larger than 0.
I tried to manually adjust the set screw by loosening it about 3 turns which results in the following mechanical rest position but now the ECU throws a code for P1683 - Throttle Valve Default Position Spring Performance Problem.
So, I tightened the screw by 1/2 a turn and now no CEL is thrown but upon visual inspection, you can tell that the TPlate% reduces very slightly as TPedal% is increased from 0% to 2%. The attached datalog and picture mentioned above is from the throttle body adjusted as such.
I hope the reason I don't want the throttle plate to close when I press on the pedal is obvious to everyone reading this.
So, what can I do to make sure the TPlate% during ECU control in 'decel mode' is equal to or higher than the mechanical rest position?
This is not a problem when not in decel mode (overrun mode) as the ECU does not relinquish control of the throttle body.
Can someone take a video comparable to the above mentioned videos? Same with the attached datalog?
Can the following table please be exposed for the S2000?
Is there some calibration procedure I can do? I've tried to pull the ECU fuse, let it warm up to above 196F and idle for 5mins. This produced no observable change.Minimum throttle opening compensation
This table adjusts the throttle opening upon overrun by coolant temperature
Settings all values to -100% will disable the overrun throttle opening.