Subpage of Idle Control Settings

Idle Control General

Control Type

• PWM: Used with PWM type idle control valves, either two wire or three wire types, for best control apply external Schottky diode flyback.
• Stepper: Used with stepper motor type idle control valves both bi-polar and uni-polar stepper motors are supported.
• ON/OFF: Used with old-style bi-metallic valves.

Control Enable, Max TPS Value
Idle control (and Overrun Fuelcut) are active below this TPS threshold.

Idle Target RPM Cold Engine
Enter the RPM you wish to hold the engine when cold.

Max Temperature for Cold Idle RPM
The cold idle RPM is held up to this temperature.

Idle Target RPM Warm Engine
Enter the RPM you wish to hold the engine when warm.

Min Temperature For Warm Idle RPM
The warm idle RPM is held above this temperature.

Idle Afterstart RPM, Added Value
Just after starting up, raise the idle RPM by this much, while afterstart active.

Idle Afterstart Rampdown Time
Lower the Afterstart added RPM linearly down to 0 after each set cycle Time.

• Before 1.2.15 firmware trapeziod behaviour is used, this means: after Idle Afterstart Rampdown Time seconds lower "afterstart added rpm" with 10 rpm per 100msec until 0. As can be seen "Idle Afterstart Rampdown Time" in trapezoid behaviour is wait time before decrease. Example: "afterstart added rpm" = 200, "Idle Afterstart Rampdown Time" = 5; Total Afterstart duration = 5 + 200/10rpm * 0.1 = 7 seconds.
• From 1.2.15 firmware and up a triangle behaviour is used, this means: after Idle Afterstart Rampdown Time lower "afterstart added rpm" with 10 rpm, reload timer with "Idle Afterstart Rampdown Time", iterate until added rpm 0. As can be seen "Idle Afterstart Rampdown Time" in triangle behaviour is cyle time. Example: "afterstart added rpm" = 200, "Idle Afterstart Rampdown Time" = 5; Total Afterstart duration = 200/10rpm * 5 = 100 seconds.

Refpos Addition for MAT, Slope
Compensation curve for IAC reference position based on MAT, selected slope scaled with current MAT reading and is added to IAC reference position.

Example: Selected slope 12.5%, 32 Step / 70C:

@ 35 degree C MAT this would result in: 35 / 70 * 32 = 16 added Steps (or 6.25 % Duty).
@100 degree C MAT this would result in: 100 / 70 * 32 = 45 added Steps (or 17.8 % Duty).

IAC Follows TPS When Not Idle
When the TPS is above the idle threshold, normally the IAC reverts back to the reference position selected from the IAC Reference Curve, PWM. You can choose to let the IAC valve follow the TPS for smoother transients in low load driving.

IAC Forced Closed Minmap
When Map value is bigger the this threshold the IAC Position will be set to the Iac Forced Closed Position.
Normally 510 (disable); Useful when Turbo pressure escapes through IAC valve on boost.

IAC Forced Closed Position
When engine MAP value is bigger than IAC Forced Closed Minmap value, the IAC position is forced to IAC Forced Closed Position.

IAC Alpha-N Load Compensation
Alpha-N only, IAC contribution to internal load (added to TPS). Max 12.4% (at 100% IAC duty or 255 IAC steps). To disable set this to 0

For testing:
VemsTune can set a fixed IAC position, see: Tools menu/IAC Lock.