IAC causing issues

[Maverick6888]

Hi guys,

Im having a strange problem when trying to get my IAC working correctly.

some background info - My V3 has 4 ignition drivers and 4 logic level drivers instead of the 8 ign drivers. its serial No is 3253 if that helps any.

so, I have wired my fuel pump solenoid to EC36-15 as suggested in the manual and my Fuel pump relay provides +12v power to my injectors, coils, fuel pump, idle control solenoid, WBO2 and a few other things so its pretty much running everything no problems there.

i have wired my IACV to one of my spare ignition outputs EC36-24 and it was working fine using 125hz PWM i managed to get full control over the idle speed using IAC Lock tool so that was all good too.

in playing around with it today i noticed the following issues - when powering on the car, the fuel pump primes for the 2 seconds it is supposed to but it does not shut off as it is supposed to, the relay is holding closed for some reason, leaving everything powered up.

If i go into my assign outputs dialogue and turn the IAC channel to disabled, the Fuel pump relay goes back to normal and operates as normal shutting off after the prime after a power cycle of the VEMS/CAR.

As well as, during testing with the fuel pump relay in its stuck on fault condition, if i go into IAC lock and set it to 255 - max - then the injectors start cycling at a strange rate, if i lower the IAC DC the injector cycling rate also slows down to match it.

if unplug the IAC but leave it activated on output EC36-24 in the assign outputs box then the problem is not present.

if i have the engine running while it is in the fault condition, it also gets a  TOO MANY PRI TRIG flag come up and naturally the engine misses a few cycles.

im thinking this could be a grounding issue potentially but my grounds are really good. I have tried the IAC output in both spare IGN output channels with no difference,
I have tried it in 4 different spare INJECTOR output channels and it does not work at all, ( neither did my coolant fan when assigned to those channels so not sure whats going on there)
I tried it in 2 spare 7A channels on my EC18 plug but both of those were just full time closed to ground full IAC open all the time.

Im really at a loss here im thinking about just getting rid of the IAC and using spark based idle control instead.

sorry if this doesnt make much sense.

Cheers

[Maverick6888]

in my half asleep half awake state this morning it dawned on me that all these problems are caused by flyback from the IAC.

DERP>

I should have realised earlier.

anyway, i added a 5A 400V diode across the wires for the IAC and its all good now.

FLYBACK! its real. deal with it!

Cheers

Alex