Lots of new info about the case:
These are the movies I've made today, showing how does car work:
without my participation (trying to reach idle):
manipulating acceleration:
And now the clou of today's battle:
I thought of an air leakage on the throttle seal (don't know if that's the good word for it), so I've made myselve a seal made of dense carton paper - nothing changed in behaviour of the car.
Then I've unplugged electricat control unit of throttle and started engine once more.
It WORKED!!!!
(of course kinda harsh, but still, around 1k rpms but stable).
In conclusion, the engine is fine, the plenum spacer work is fine, seals ar OK, the problem is with throttle.
Infiniti likes to be unavailable, so we have to deal with rivets:
couple moves with drill and we get:
Does the potentiometer work?
Max:
Min:
But why does it need 4 pins? Usually potentiometer needs only 2...
Did not expect that:
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to sum up: mechanically there is nothing to be broken inside the throttle, electrically mine suits range given in service manual, so what the hell...
Still, I'm sure that throttle is the problem, but how the hell is that possible?
S.