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 ?

[StarBear]

Ok, looking at Haynes page 177 on fig 9.87 current flow 1974 USA part 3: Shows G19 as air flow meter but no temp sensor. Temp 2 CHT shows as G18.
Going to 1975 on page 185 it shows G19 as afm, G17 as temp sensor 1 and G18 as temp sensor II.
No temp sensor I in our 1.8s that I can determine. Will head to butterfly test.
Also found the oil fill cap a bit loose, so that does funny things, too. Tight now.

[wonkipop]

Ok, looking at Haynes page 177 on fig 9.87 current flow 1974 USA part 3: Shows G19 as air flow meter but no temp sensor. Temp 2 CHT shows as G18.
Going to 1975 on page 185 it shows G19 as afm, G17 as temp sensor 1 and G18 as temp sensor II.
No temp sensor I in our 1.8s that I can determine. Will head to butterfly test.
Also found the oil fill cap a bit loose, so that does funny things, too. Tight now.

you could well be right as the plugs are different and i have always wondered about that.
and thats a good explanation for that plug difference.

the stuff from mr. b' site is here.

https://bowlsby.net/914/Classic/zMan_1974_1...iningManual.pdf

its in factory tech manuals section.
it is a service training manual for the introduction of the 1974 models and covers the 1.8.
however it does not mean it is correct.

i will now look into this as you are on to something.
possibly a good thing its not there. one less thing to screw up.
entirely possible they held off until 75 on the temp sensor even if they intended it to be there in 74 just to keep it simple. would just mean its slightly less refined in terms of mixture fine tuning and wasn't needed for emissions until 75 when the standards tightened?

good stuff pointing this out. the mysteries of the first L jets hey.