Traced the issue on this 80 that I'm working on to the throttle switch. Unplugging it fixes the erratic idle when the choke is pulled when the engine is cold. What exactly is the function of the throttle switch and how should it be adjusted?

 

not sure, but on the 81-85 cars the TPS basically runs the two ACV solenoids. i would bet that the SA is similar?

 

Where is this switch or connection? Do you have a picture of it?

 

Presume this refers to idle/cold start weirdness you were experiencing in another Thread?
Always helps if we can follow a story in one thread....

Thx for the post tho Dave.
Stu Aull
80GS
Alaska

 

That's the idle-detect switch. Used by the ECU to detect idle condition & it controls a couple mix-related items directly in concert with the ECU. There's an adjustment spec in the FSM, in Section 1A (emissions). Page 1A:19. It's supposed to switch at 1000 RPM +/- 50.
Wiring diagram, Section B, lower left corner of the diagram.

The Idle switch gets a +12V signal from the ECU off the GR wire when the engine is decelerating, and controls the Richer Solenoid Valve and the Coasting Valve, as well as providing a signal back to the ECU. Part of the deceleration control system.

Having it mis-adjusted could definitely monkey up your idle mix.

 

Stu, this is exactly what's messing with the cold idle choke.

I have the FSM and I'll dig into it after lunch here and post the results. I'll see how far off it is. I do have a spare just in case.