Long time no post... Not much car time of late - but when I have had car time - progress has been gooooooood.
With thanks to gslender for urging me on, the idle valve issues over the last few pages of this build thread have been
SORTED- with nothing more than a firmware update for the ECU. So we now have a working idle valve - hurrah. Evidently this ECU shipped with some wacky firmware that either disabled or otherwise failed to support an idle valve.
With that though, has exposed problems with the plumbing into the throttle bodies. In short, the vacuum/idle air plumbing that I'd envisaged
here is flawed. What is now happening, is when the A/C turns on at idle, the idle valve opens as it should (to around 60-80%) to add air-flow, but then subtracts from any meaningful vacuum reading, since the airflow coming from the idle valve exceeds that of the throttle bodies, and the subsequent airflow in the vacuum block starts to reverse. This then causes;
The fuel delivery to go way way rich, since running in ITB mode in the MS then puts me at the top of the fuel table rather than the bottom around the correct idle range, since the ECU is seeing the wrong MAP reading
I lose vacuum for brake boosting, so with the A/C on I might occasionally (and some would say unpredictably) arrive at a set of lights or intersection with a rock-hard pedal from time to time... (totally not dangerous at all)
SO - that has led to the development of a little air distribution block that looks something like a weird musical instrument - a car-flute if you will;
The basic idea here is that it will feed additional air to the runners when need be without changing the direction of airflow in the vacuum block - which is where the MAP reading is taken from.
The idle valve mounts on the block, covering the two big holes in the middle and metering air when necessary.
The diagram tells the story better than words - the air distribution block is at the bottom of the sketch;
Funnily enough - this time last year we were on the way to the maternity ward for the delivery of my daughter. Tomorrow is her first birthday... and then when the relies clear off and its time for naps, I might bolt the car flute in place and see what happens...