Hello from Bulgaria

[dexter_lab]

Hi there,
car is Mazda MX5 with FE 2.0 engine (from Kia sportage) with small turbo
I want to migrate from MS to a microRusefi.
All looks fine except the management of idle valve. The IAC valve is 3 wire bosh 280140553. When not connected, is semi open, 2 coils one is closing it other opens it. the question is:

Can I manage this IAC with microRusEfi? (no additional hardware)

[AndreyB]

Not sure about the hardware - maybe we have enough. We definitely do not have software to support such a valve. https://github.com/rusefi/rusefi/issues/1122

is it two solenoids inside or what is it?

[dexter_lab]

yes, there are 2 solenoids inside. it is one between pin1 and 2 and one between 2 and 3. when both open circuit there is spring that keeps the valve semi open. Applying current on first coil and valve starts to close, applying on the second and it start to open.
I have bench testing on the MS to split the PWM signal and to invert the second one. Of course it starts to heat as trough both coils current is flowing(if I remember correctly it is around and 1A).
Then I made a small board to get the PWM and if below 50% to feed the first coil with % = 50%-Current_PWM second is off, if above 50% duty cycle, the % for the second is = Current_PWM-50% and fist is off. All this was bench tested and except some mechanical noise the generated heat was bearable. Still do not know how the valve will behave in real world when air is passing (if any effect on open close when valve is not powered).
Idle should be closed loop and the ECU will command the valve to adjust the rpm. When exit the idle mode and throttle is open it's not so important (I believe) what is the position of idle valve as the air will flow through throttle body. but when car is on speed and gas peddle is depressed the valve should maintain some air thorough it to keep of too much vacuum right?

[AndreyB]

car is Mazda MX5 with FE 2.0 engine (from Kia sportage) with small turbo

pics? what generation MX5? how hard is the swap?

Then I made a small board to get the PWM and if below 50% to feed the first coil with % = 50%-Current_PWM second is off, if above 50% duty cycle, the % for the second is = Current_PWM-50% and fist is off. All this was bench tested and except some mechanical noise the generated heat was bearable.

this confirms that we have all the hardware needed we just need a few lines of software. The biggest challenge would be to test this

[dexter_lab]

the idea was "start from the scrap"
gear box was from miata, the bell is from mazda B2000, engine is FE3 from kia sprortage (same engine as in mazda 626)

Miata is NB, no VVT 1.6 no AC, here are some pics

CIMG0688.jpg (147.27 KiB) Viewed 8060 times

CIMG0848.JPG (160.85 KiB) Viewed 8060 times

DSC_1342.JPG (1.27 MiB) Viewed 8060 times

[Sullivan]

Hello, I am new to your forum as of today.. I am from Alberta, Canada. I am really happy to be a member of this forum. thanks.

[dexter_lab]

Hi, finally a progress (after a weekend full of attempts) on making idle to work. There is idle valve with 2 coils and 3 wires. No electricity the valve is semi-open, applying current on the first coil then valve starts to close. IF apply current on second, starts to open. This is how it looks. My main goal (together with controlling idle) is to make the idle management efficient, as above 50% on coil brings to much heat.

idle_fig1.png (306.95 KiB) Viewed 6611 times

Some history, the original valve that match to vehicle harness is with 2 pins, normal closed with additional screw to manage base idle, but I have to change the throttle body (and the whole engine and current throttle body is with this beast. Initially I was thinking let’s keep the harness, I will put 12V on the 2 wires and will make one short to chassis. Also, Mega2 was present that has only one PWM for idle (or at leased I do not know for another config), so I did a small pcb with atiny45 that was reading the PWM from mega, do simple translation to feed 2 high side drivers – sounds complicated as not possible to manage the board from TS. So I abandoned Mega2 and goes for u_rusefi .
In rusEfi there is something called double solenoid mode. So far so good pin for idle was decided to be 3 or Lowside 2. For second pin it must be 7 or Lowside 1. Then hoe, not possible to select if from available pins.

idle_fig2.png (34.87 KiB) Viewed 6611 times

So I was thinking what I need to manage the solenoid some PWM that will keep it closed on the first coil could be constant. Then from idle to manage the second coil in order to change the quantity of air passing through the valve. Then I found a new (for me) feature FSIO.
As it is written win WIKI (https://rusefi.com/wiki/index.php?title=Manual:Flexible_Logic): lexible Logic is the fanciest-schmanciest feature of rusEfi. Flexible Logic allows advanced users to get unprecedented level of configurability for custom outputs and engine control. rusEfi supports up to 16 flexible outputs, each of these could be either an on/off or PWM signal. In case of a PWM signal the frequency is defined in the configuration and the duty cycle is dynamically controlled by the evaluated expression. – very nice exactly what I need.
NOTE: in order to save changes to the board, the engine revs must be 0. I have to disturb Andrey for this (I’m so sorry)
There are 2 screens in TS that must be updated to make it works. I have started with simple case let’s have a constant PWM on pin7 (Lowside 1). On the screen below we will define output one to be manifested on pin 7 with frequency of 460Hz.

idle_fig3.png (48.91 KiB) Viewed 6611 times

Then a condition that is defining the duty cycle of PWM must be set. Here the syntaxis is not so human readable. What is set up means that duty cycle will be 16% in case revs are above 1300. Just for reverence 0 means no duty cycle 1 means 100%

idle_fig4.png (28.98 KiB) Viewed 6611 times

Following pictures illustrate how the valve is working
When rpm is above 1300 and idle is 0%

idle_fig5.png (552.97 KiB) Viewed 6611 times

Yellow is the fist coil blue(magenta) is the second coil

idle_fig6.png (723.88 KiB) Viewed 6611 times

Note when connected to car I will increase the % on the first coil just before engine stall, and make it works till from 1300 to 2000 rpm to be used as engine brake.
Now let’s open that valve I put manually 60% on manual in TS (note gauge shows something else (duno why)

idle_fig7.png (586.48 KiB) Viewed 6611 times

Now the scope looks like (a bit ugly) 75% duty cycle..

idle_fig8.png (564.44 KiB) Viewed 6611 times

And of course, the valve is almost open (almost because PWM on first coil)

idle_fig9.png (525.9 KiB) Viewed 6611 times

Than I play with frequency of the PWM, started with 60Hz, too big vibration slowly going up until 700Hz when valve is stable and noise is very low.
To be continued….. when put on the car

[AndreyB]

https://github.com/rusefi/rusefi/issues/1122 option was added to TS but code was not finished