|
I don't think that was the post. That link referred to later adaptable ECUs, which started with LH2.4, I think. I dunno nothing 'bout Motronic, but obviously the EFI technology was more in code than hardware by then.
One thing that changed with LH2.4: the IAC motor became a spring-return, one direction motor (two wires), compared with the free movement, two coil motor in yours. The duty cycle is still used to control its average opening, but now the mass of its armature and spring determine the time to rest position.
I was hoping to see if Abe Crombie discussed the design (LH2.4) whereby its opening is by default a small amount, as if for a limp-around idle, should the control or motor fail. Applying voltage actually takes the valve through the fully closed position before reaching fully open. On the three-terminal idle valves, I'd guess yanking the connector would have the opening in a random position, possibly at 3000 rpm, hence the need for the ECU pin you short to mimic off-idle opening.
Pin 19 is a good question. In my LH2.0 cars it seems to be an undocumented MPU input, level converted with a transistor. The 83 manual does not show any harness jumper to ground, but the 84 diagram does.
On my sample -544 ECU, Pin 19 has the input protection parts installed (so you'll see the pull-up to 5V attempt if you disconnect it) but the level convertor transistor and associated parts are not installed on the board-- so it essentially does nothing.
Plausible explanation? Could be this is a relic of unheated 02 sensors, that being the major change made in 84 year to LH2.0? Perhaps this was a program jumper to indicate the use of a heated sensor, changing the warm-up map. I don't know. I can't find the documentation if it is there.
--
Art Benstein near Baltimore
|
