Idle Speed and Air Temp/Humidity Options

[StarBear]

As getting ready for the 2022 Northeast Gathering, I'm encountering a semi-recurring idle issue on my 1974 1.8L LJet FI. When outside air is cool and dry, idles just fine at 950-1000 rpm. When outside air is warm and humid, after warmup the idle falls off to barely running. I've just been adjusting the air flow screw (maybe 1.5-2 full turns) to open it. Of course, the reverse happens - if I preadjust the screw it idles near 1800 then settles down to 1100 after the engine gets totally warm (15 mins or so).
I presume (?) there SHOULD be some regulation, perhaps with the ECU or AFM, to monitor air temp and humidity and make adjustments automatically? I didn't have to manually do this adjustment in the past.
The AAR works and tests out fine. Just annoying to have to pull over after running a while and adjust the screw. (IMG:style_emoticons/default/dry.gif)
Your thoughts @Van @Van_B and @Wonkipop ?

[Van B]

Yeah that is definitely the ‘74 AFM right there!

[wonkipop]

Yeah that is definitely the ‘74 AFM right there!

yes
more like what i thought it would be.

i would say that counterweights on the units that @nihil44 has posted in the other thread are due to them being rebuilt units? the counterweights don't appear to be stock? the unit above looks stock.

it seems to me on the 74 that the temp sensor is feeding into pins 9 and 8 on the plug socket - as much as i can tell anyway and its modification of the signal is fed out via that circuit to the ECU.

the later ones in 75 are using pin 6 and an additional pin 27 added to the plug and ECU.

would suggest you might be able to test 74 AFM by taking the top off and testing at those two electrical connections from temp sensor I? if you had test reading data to check against? dunno. only ever found that 912 test.

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not sure what to make of @StarBear test above.
seems like his AFM is correct when tested cold.

can't really think what to make of his warm test or the why of it.
the AFM is sheltered from engine heat. isolated via intake boot and plastic air cleaner casing from direct engine heat conduction and is perched high in engine bay. i guess electrical circuits are all warmed up. but don't know what to make of it. don't think it matters. his test would seem to say his AFM is ok. (IMG:style_emoticons/default/confused24.gif)