IAC setup

[volvotech]

hi Rob
i have about resolved my install & setup,but need some help with iac .
cannot use std stepper idle,so intend to use Bosch 3 wire unit but short of outputs suitable,bit concerned with stepper outputs on vems only 1 amp,valve i intend using (volvo v90,960,t5) draws .9<>1.2 amps @13v according to volvo tech data.do you think it advisable to build a pair of external driver circuit (i have a fet circuit (using 530IRF fet).
regards Adrian

[rob@vems.co.uk]

The stepper can handle 1A and provides a 12V supply... I'll do some reading...

[volvotech]

Hi Rob,
if you need schematic of my fet circuit can provide if it will help,should be ok for all the low current driver outputs.It's a low component count circuit with built in flyback,fet rated 100v/16a,can also invert outputs if needed,i'm not bad at this stuff it's more in my job line.
regards Adrian

[rob@vems.co.uk]

Cool, I'm just wondering what the 3pin's function are... Is it like any of these:

Bosch 0 280 140 505 (Also VW Audi 034 133 455):

    * Shape: outlet at 90 deg to inlet
    * Total length: 141 mm
    * Position unpowered: less than 1/4 open, spring centering
    * Connections: Terminals marked 1,2,3 (looking at connector with central notch on top), when connected as per Pers diagram(1: +12V; 2: grd via 10 ohm; 3: to MS) the valve will be open with 3 open, closed when 3 is at 12V.
          o This valve will NOT close when connecting 3 to grd, as it should when connected to MS Idle out. This is why it will always be open when hooked to MS. Played with other ways to hook it up, could not find one which worked.

Bosch 0 280 140 501

    * Shape: outlet and inlet in-line
    * Length: 107mm
    * Position unpowered: indifferent, no spring
    * Connections: terminals marked 3,4,5 (as above). with +12V connected to central terminal the valve will be either open or closed with either 3 or 5 conncted to grd.

Bosch 0280 140 516

    * Shape: inlet at 90 deg to outlet, cast body
    * Length: 124 mm
    * Position unpowered: closed, spring loaded
    * Connections: two pins. Will open when applying dc, nice linear response in the range 1 to 9V, 1A at 9V (open)

[volvotech]

Hi Rob,
Volvo idle valve Bosch 0 280 140 542
Terms 1 2 3
+12v >2
Resistance accross 1<>2 10-14ohms
                           2<>3 10-14ohms
Non Centering (no spring)

Hope this helps will do a bit of testing tomorrow to se if will respond to pin1 to ground & control from 3,but i suspect it requires open & close instruct pwm from ecu.
will tidy up my files & pics & e-mail to you & post anything you think is of use to others.
regards Adrian

[rob@vems.co.uk]

The team are still saying to use the stepper driver, its even got internal flyback diodes.
I will crack the scope out tomorrow and do some dual solenoid tests.

[dnb]

The stepper driver seems pretty robust!  I have abused mine plenty in the past when I was trying things out on the TVR.  Motors are pretty nasty things when all said and done - steppers especially.  So there shouldn't be much problem with using this to control a normal idle valve.

Incidentally, is there a way of having 2 of this sort of idle valve? (not stepper motors)

[volvotech]

just a point to note,as far as i can tell from volvo technical data,this idle valve is same as late 850 & V/S70 idle valve they all end up at same variant no in stock system.Sop if anybody done 850/70 series with Vems may help.
regards Adrian

[rob@vems.co.uk]

These are also used in some of the BMWs, its a IACV thats been used before, but usually we have either spare FETs or IGBTs to drive it with.

The stepper should work but we need to limit the current to less than 1amp, which suggests a bit of resistor work is required.  What resistance do the coils read?

Rob

[volvotech]

Hi Rob
coils read 10-14 ohms each.
just a thought but might i be better using external fet circuits to drive iac valve ?.will post my circuit idea when i figure out how to attach images?
regards Adrian

[rob@vems.co.uk]

FETs will probably be best to drive the IACV, but at the same time it would be nice to see the thing driven entirely from VEMS

[Sprocket]

Just curious as to why you cant use the standard stepper?? or use a bipolar steper valve rather than the fidle valve.

I have found that the Rover valves are Unipolar, these can be converted with a little fiddling but there is a far better option. That is to use the bottom bit of the rover valve and then fit a stepper motor from a puegeot wich is bypolar to start. either way works and I know the config as I spent many hours researching and fiddling in the dark, lol