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]

Steve, sorry for the delay, I’ve been traveling for work and forced to do things like socializing after hours lol…
Anyway, next time it’s all hot and steamy, you should grab hold of the throttle body and try to force the butterfly closed. If the idle drops back to where it’s supposed to be then I think you may have a worn TB that’s not seating and reveals itself when the metal heats and expands just enough to not seat properly.

[StarBear]

next time it’s all hot and steamy, you should grab hold of the throttle body and try to force the butterfly closed.

Van; could you explain just a bit how to do this? I get the concept but not the action. Thanks!!!

[Van B]

next time it’s all hot and steamy, you should grab hold of the throttle body and try to force the butterfly closed.

Van; could you explain just a bit how to do this? I get the concept but not the action. Thanks!!!

When the car is idling just grad the arm where the cable attaches and try to twist it further closed. Sometimes you won’t really feel movement but your idle will drop. That’s how I learned my TB was worn out.

[StarBear]

next time it’s all hot and steamy, you should grab hold of the throttle body and try to force the butterfly closed.

Van; could you explain just a bit how to do this? I get the concept but not the action. Thanks!!!

When the car is idling just grad the arm where the cable attaches and try to twist it further closed. Sometimes you won’t really feel movement but your idle will drop. That’s how I learned my TB was worn out.

Got it. Thanks. Will test with oil filler cap now tighter first, then if still happens will do this test. (IMG:style_emoticons/default/biggrin.gif)