The air bypass in the AFM isn't meant to be used as an idle adjustment... it adjusts the airflow across the whole scale. It's a bad idea to employ it for any type of fuel tuning. Get a real fuel controller or go stock... you're just going to melt something.
I didnt adjust the idle bypass, I played the toothed wheel setting. In the stock form the VF showed it was adding fuel to the short term trims, in the 3.5 to 5v region. So I richened it one tooth and brought the VF into the 2.5 area with brief operations plus/minus of that.
Just for my own edification.... Just how does opening something to atmosphere FIX a vacuum leak?
My vacuum leak was the small hole I said drilled in the filler cap. If not and manifold vacuum is present in the crank case, my front and rear main seals vibrate like a harmica, sounding like a worn out throwout bearing. Thus creating a small vacuum leak post AFM. Now with the crank case vented to atomoshphere and the vacuum line plugged top the intake, the leak is gone.
EVERY MKIII runs closed loop 90% of the time... '86.5, '87 and earlier are no exception.
OK, so there is no O2 swing at idle. It does run a constant 15.5 tho on the wideband, just no corrections. Figured with the narrow band cooling at idle, they would not use an unheated O2 for idle closed loop. Only thing I can think of is, Im running the later model coolant temp sensor (since its a 90 Cressida harness) and maybe the earlier sensors had a different resistance. Ill look up the checks for those and see if the ohms reading is the same between each.
You can't use Vf to tune. P E R I O D. It serves as a rough guide at best. And you can't even use it a a rough guide for open loop operation.
I know I cant use it as an open loop feedback...Im happy with the mid 12's the map is giving me. Why cant we tune with the VF? With a wideband installed and seeing what the ECU is doing with short term trims, if its maxed out rich or lean, I dont see a problem using it for tuning since we dont really have any other way of knowing. I thought I would get to it before the ecu learned and stored it into longterm, only to lose it if the battery dies?
Heated O2 sensor? Sure, why not? Just use a relay triggered by the fuel pump relay and with it up for 12v. You can't just wire in a wideband O2 sensor though.... just narrowband.
I have some spare heated narrowbands. Ill look into installing in a few weeks. Im going to see how this setup will run on a day to day basis as is. Im aware of the wideband operation. I have a Turbo Volvo with 500whp. Its running a DSM ecu and is tuned with ECMLink. Whats neat about that is it will take the wideband input and I can determine switch voltage and actually run stoich at 15.5 and gained almost 5mpg over the stock narrowband.
Im running the Wideband on the truck just for feedback only.