MembersPage/SteenAndersen/Questions (2005-08-14 06:29:30)

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Questions

How do i change the IAC PWM Frequency ?

I have been testing my Idle Valve with the PWM output from GenBoard. The valve is a BOSCH 2 terminal spring loaded type 0 280 140 531 from a 91' car, 8.7ohm DC resistance thats a 1.4A LoadI use iac_sol_channel=60 for IAC output.I experimented with mdi00..mdiff command to se the valve open and close, and it seems to work, but i hear the PWM frequency as a high pitch (i read 2 KHz somewhere). But the inductance/hysteresis/losses in the Valve is so high that it gets VERY HOT ! I get so hot that i'm afraid it will fry if used in the car in a hot engine bay.

The PWM Frequency is way to high for this old Motronic Idle Valve, it should maybe oprate at 100Hz not 2KHz.

I have been lookin in softpwm.c and iac.c but i do not understand what's going on in the code (I'm not used to C programming). OK i see that the PWM duty cycle is set in iac.c with this.\n

	softpwm_set(&idle_pwm_soft, pos);

but i dont see any frequency settings in the init_iac procedure theres just one statement.\n

        softpwm_init(&idle_pwm_soft, 0);


My subpage for questions that i need an answer to. Questions witch i have solved or feel is answered is moved to MembersPage/SteenAndersen/History page