High idle, probably broken IAC, questions

[fixkick]

show and tell
our IAC is here.
fast idles pins on ECU false.(disabled, not active)
1991 actual mine. the gap here closes at about 150f.  for sure, must, close


do you have our bleed screw, CW max gently is zero vacuum leak at bleed and lowest RPM possible unless other things leak.
Is yours with this large bleed there?  there are 51 marketed cars sold world wide, I have never seen them all, no me. post your photos?


all comments are USA spec 8v 91 to 95. (EPA banned 8v in 1995 end.)


not TB holes all.  see that oval hole that is all TB IAC + bleed air flow.
see that top half there is gasket there too that loves to fail  get hard ,crack and suck in the gasket, and leak air like mad and fail.




TB rear.  THE brass TV plate must be fully closed, .001" gap max I set them to 0.0005" 1/2 a thousands of an inch if MOLESTED by carb guys(their excuse not mine)





here is my home made gasket took me 5min work.

rules of gasket.   the 5 tiny holes right of big bore must  be blocked by the gasket or fails hard. Seem more here. seen frame 36 too.!
if you cut a gasket with IAC hole on left blocked, this ends IAC forever and bleed adjuster too.
I also do this to prove OMG with blocked hole air idle hot is 2000 rpm still and so know know TV is not it if TV is closed per spec, .001" or less.
TV is brass, throttle valve, and must be fully closed, if not hacked, or TB has no bleed valve.



There are only 2 causes, macro
1: ECU fast idle , pins wrong set to enabled.
2: vacuum leaks vast.

The rule state is nature on earth abhors a vacuum always rings true. for sure this class engine. (like gaskets suck in, or wax pellet in IAC dead, hoses crack ,diaphragms crack.)
on 30 year old car expect 2 failures not just  one. I would.

good luck.!!!!!