On a 2.0l 16v corrado what controls the voltage to the isv? Ecu or an independent sensor? reason i'm asking is because my idle is completely bonkers, it idles at anything from 500rpm to 1800rpm! Just before car was fully warmed and idling at 1500rpm,isv was held open by 12.5v getting to it causing it to idle to fast. Surely it shouldnt be getting 12.5v to it with engine fully warmed up? Isv is clean and not sticking. Any help would be good. Cheers Edited by: sambo
Assuming it's a 9A it'll be running KE Motronic where the ISV is controlled by the ECU. The ISV does get 12V's but it is an occilating 12V, depending on the type of multimeter you're using you may not detect this.
On the Golf MK2 16V, there is a separate control unit behind the centre console that controls the ISV. I would guess that the same setup is used on the 2.0L 16V as well. Edit: Golden got in there first with a reply and what he says is likely to be far more accurate Edited by: Trev16v
I am using a digital multimeter and assuming oscilations arent very fast in frequency i should be able to notice it right? All i am reading is 12.5v constant. If i pinch the vacume hose revs drop to normal. Its very annoying could it be dodgy idle valve even if it seems to be ok?
The ISV is PWM controlled at a faster freq than a DMM will notice, so if you're reading battery voltage constantly then something is up.
although the ISV voltage uses PWM, a DMM should still give a perfectly reliable reading of the effective analogue voltage, and from that you can calculate the duty cycle (if you needed to). a reading of 12.5v could suggest a near 100% duty cycle - which may be due to the controller reading under 1k rpm all the time. on my k-jet system i get a reading of 6-7 volts going to the isv when it is buzzing, without the engine switched on. i take this to be a 50% duty cycle in this 'primed' state. note that the isv controller on k-jet will notice if the isv is plugged in/unplugged and will switch itself off. i.e. if you turn the ignition on the isv will buzz, but if you unplug the isv and then plug it back in it won't buzz any more - you need to switch the ignition off and then back on to get it to start up again. i guess the ke-motronic will do the same thing. you should be able to test the isv with a battery and a variable resitor. Edited by: GTI
Digi1 adjusts the current to the ISV via the ground wire (+v is powered straigh from main EUC feed), don`t know if this is the same as yours? Is there a basic settings procedure you can use to get the idle set up?
I had another go at checking relevant things and i'v found that there is an intermittent brake in a wire to a microswitch on the throttle body. Bit of fiddling and idle drops back to normal Just took off the TH body and discovered it is in fact a throotle pot sensor with micro switch built in, didnt realise motronic ecu used one of these. Gona try and find the brake and repair it, if that fails will have to get a new sensor, anyone knows how much it costs?
That is quite DMM dependant, generally not recomended! An analogue meter, (needle type) will give much more consistent (not accurate!) results.
