Idle Stop Solenoid

[blurple124]

I have had some high-idle issues with my 1978 1.8L with an ADFA-11 carb. The car "idles" smoothly at about 2500-3000 rpm.

Yesterday I unplugged the solenoid on the carb, just for giggles, and the rpm dropped down to about 1500, but now the car is missing and sputtering.

Alot of the wiring for the emissions system is disconnected and dangling from the work of previous owners, so I have removed the emissions equipment from the car. This solenoid seems to be getting constant power and is not disengaging.

What is the best solution here? Can I unplug the solenoid and tune the carburetor to compensate, or do I need to fix something else?

[So Cal Mark]

that solenoid stops the fuel flow through the idle circuit and should have power when the key is on. If you disconnect power through it you will have to keep the idle high enough to run on the main circuit or the engine will stall constantly

[manoa matt]

On a 1978 the idle stop solenoid should be powered by a grey wire with a red stripe. As Mark stated the wire should provide power to the solenoid when the key is on, and should not be energized with the key off.

[blurple124]

Well, in that case, it seems to me that the solenoid is doing its job, but why is the car stuck idling at 2500 rpm then? I have cleaned the carb and the throttle linkage is fine. Is it a bad jet?

[majicwrench]

Bad jet not causing high idle. HIgh idle is way too much air getting in, throttle plate likely being help open. Do you know where idle screw is?? Is choke plate open?? Fast idle cam?? If everythign was correct, you would unplug idle sol and car would die. The idle dropping when it is unplugged shows that it is likely working. Look elsewhere.
Keith

[blurple124]

Okay. Perhaps some details can help those of you with more experience assist me in diagnosing the issue:

Turn the car on initially, and the engine will idle where it is supposed to.
Hit the throttle, and the engine will start to idle higher each time until it consistently idles (smoothly) at 2500-3000 rpm.
When the engine is cold and the solenoid is unplugged, the engine will stall out.
When the engine is warm and the solenoid is unplugged, it will drop to about 1500 rpm and start missing, running really rough.

Carburetor is a 32 ADFA tuned to factory settings.
Has been sprayed with carburetor cleaner and been through a parts washer.
everything seems to be actuating properly (ie throttle linkages and plates).

No internal performance modifications have been made to the engine.


What is the cam you are referring to? I am not familiar.

[majicwrench]

Is choke plate open when engine warm?? Something is holding throttle open, should be pretty simple to see what. Is choke plate open with engine warm?
Keith