Idle Stop Solenoid
Thread Starter
Burning Brakes
Joined: Oct 2004
Posts: 920
Likes: 1
From: Shelby Township Michigan
Idle Stop Solenoid
In my efforts to make sure my Quadrajet is properly set up, I noticed that the Idle Stop Solenoid makes no movement at all. I checked and there is 12v to it.
Where can I get a new one and are these rebuildable? If rebuildable, who sells a kit.
Thanks,
Dino
Where can I get a new one and are these rebuildable? If rebuildable, who sells a kit.
Thanks,
Dino
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
check it with an ohm meter to see if it opened up. Also make sure it isn't just stuck, if so clean it up and you should be good. Might be a junk yard part, don't know if you can get em at Napa or somewhere
Thread Starter
Burning Brakes
Joined: Oct 2004
Posts: 920
Likes: 1
From: Shelby Township Michigan
I did not check it with the AC on. I know that there is 12v to the solenoid at the time I checked it.
I am not totally clear on the purpose of this solenoid. Can someone give me a description?
Thanks,
Dino
I am not totally clear on the purpose of this solenoid. Can someone give me a description?
Thanks,
Dino
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
the Idle Stop Solenoid is supposed to kick the idle up a bit when you turn on the AC to compensate for the extra load at Idle. If you have 12v at the solenoid all the time something is wrong. Disconnect the wire and see if it drops out. Ohm ut the solenoid to see if the coil inside is open or intact and check to see if the plunger is stuck.
Here is the schematic for an 81, should be pretty close
Here is the schematic for an 81, should be pretty close
Thread Starter
Burning Brakes
Joined: Oct 2004
Posts: 920
Likes: 1
From: Shelby Township Michigan
Originally Posted by SIXFOOTER
the Idle Stop Solenoid is supposed to kick the idle up a bit when you turn on the AC to compensate for the extra load at Idle. If you have 12v at the solenoid all the time something is wrong. Disconnect the wire and see if it drops out. Ohm ut the solenoid to see if the coil inside is open or intact and check to see if the plunger is stuck.
Here is the schematic for an 81, should be pretty close
Here is the schematic for an 81, should be pretty close
Thanks! That makes a bit more sense. I bet there is some type of wiring issue since the AC is not working properly.
Thanks,
Dino
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Tech Contributor
Joined: Aug 1999
Posts: 14,376
Likes: 6,375
From: At my Bar drinking and wrenching in Lafayette Colorado
The idle solenoid was also used on non-A/C cars as an "anti-dieseling" solenoid. The idle speed was set using the solenoid hex adjustment, and the idle speed screw on the carb was set to a very low (about 450 rpm) idle speed. When the engine was shut off, the solenoid would close the throttle and prevent engine run-on after shut down.
If you have 12 volts to the solenoid, it should "snap" out to the extended position, regardless of A/C situation. If not, it is defective.
If you have 12 volts to the solenoid, it should "snap" out to the extended position, regardless of A/C situation. If not, it is defective.
Le Mans Master
Joined: Jul 1999
Posts: 9,206
Likes: 17
From: Sewell NJ
Originally Posted by lars
The idle solenoid was also used on non-A/C cars as an "anti-dieseling" solenoid. The idle speed was set using the solenoid hex adjustment, and the idle speed screw on the carb was set to a very low (about 450 rpm) idle speed. When the engine was shut off, the solenoid would close the throttle and prevent engine run-on after shut down.
but I'll add that my car is a 74 AC 4 speed car and it also uses the solenoid for antidieseling. The compressor has no effect on its workings in stock form. Also, the solenoid does not push the throttle to a given position. If you start the car with the solenoid disconnected and, once running, connect the solenoid without moving the throttle it will do nothing. It's not strong enough to move the throttle against its springs. It acts as a limiter that prevents the throttle from being closed passed a given setting.
Team Owner
Joined: Jun 2001
Posts: 23,367
Likes: 1,061
From: Virginia USA
Originally Posted by lars
The idle solenoid was also used on non-A/C cars as an "anti-dieseling" solenoid. The idle speed was set using the solenoid hex adjustment, and the idle speed screw on the carb was set to a very low (about 450 rpm) idle speed. When the engine was shut off, the solenoid would close the throttle and prevent engine run-on after shut down.
If you have 12 volts to the solenoid, it should "snap" out to the extended position, regardless of A/C situation. If not, it is defective.
If you have 12 volts to the solenoid, it should "snap" out to the extended position, regardless of A/C situation. If not, it is defective.
The name is "Idle Stop Solenoid" not "Bump up the idle when the AC compressor is running solenoid".
My '71 non-AC car had it but it's long gone.
Melting Slicks
Joined: Mar 2006
Posts: 3,342
Likes: 7
From: Connecticut
Originally Posted by SIXFOOTER
the Idle Stop Solenoid is supposed to kick the idle up a bit when you turn on the AC to compensate for the extra load at Idle.
Mine is not present and the idle drops from about 800 RPM to about 500 RPM when the compressor kicks in
I need to find one before next summer
Thread Starter
Burning Brakes
Joined: Oct 2004
Posts: 920
Likes: 1
From: Shelby Township Michigan
Thanks for all of the responses. It's answers like these that keep my interest peaked with this forum.
I will take the solenoid out this weekend and look it over. I have found some replacements and will most likely replace it as soon as I determine if the old one is bad.
This is my process of learning each function of the Quadrajet carburetor. I think this carburetor is an excellent device that I need to study up on.
Thanks again,
Dino
I will take the solenoid out this weekend and look it over. I have found some replacements and will most likely replace it as soon as I determine if the old one is bad.
This is my process of learning each function of the Quadrajet carburetor. I think this carburetor is an excellent device that I need to study up on.
Thanks again,
Dino
Instructor
Joined: Dec 2005
Posts: 196
Likes: 0
From: Burlington WI
Wish my 81 had a idle speed controller. I understand some did, but I don't think I have the computor wiring for controlling it. My carb likes to
load up rich like waiting in a fast food driveup line and in gear it totaling
fustrating to have the engine shaking not to mention the exhaust fumes
for the cars behind me.
load up rich like waiting in a fast food driveup line and in gear it totaling
fustrating to have the engine shaking not to mention the exhaust fumes
for the cars behind me.
Instructor
Joined: Dec 2005
Posts: 196
Likes: 0
From: Burlington WI
You are right, the Idle Stop is for anti-dieseling, and a Idle speed with one
wire 12volt us for load control when the air compressor is on. A idle speed controller is a electric motor that screws in and out controlled
by the computor. The ones I have had apart has 4 wires to it. My
81 & 83 skylark with fuel injection use to get stuck and I use to take
them apart and WD40 the threads. The newer electric Qjets had this
system and have read that some 81's came with it, but I have not
wiring harness on my car and therefore it is easier to rebuilt the carb
than to change or rewire the computor.
wire 12volt us for load control when the air compressor is on. A idle speed controller is a electric motor that screws in and out controlled
by the computor. The ones I have had apart has 4 wires to it. My
81 & 83 skylark with fuel injection use to get stuck and I use to take
them apart and WD40 the threads. The newer electric Qjets had this
system and have read that some 81's came with it, but I have not
wiring harness on my car and therefore it is easier to rebuilt the carb
than to change or rewire the computor.
Le Mans Master
Joined: Jul 1999
Posts: 9,206
Likes: 17
From: Sewell NJ
Just to add a little more to this discussion. You can change the function of the idle stop solenoid to work with the compressor. All you have to do is splice into the wire on the compressor clutch and run it to the solenoid. Any time the clutch is energized the idle stop solenoid will set the idle at the adjusted speed. I did this to my car and it worked very well. I don't have it connected like that now because I changed my system from a VIR setup to a cycling setup when I converted over to R134. The solenoid isn't strong enough to push the idle up when the compressor cycles on and off so it wasn't worth it to keep it that way. But if your working with a non-cycling system it works very well and keeps the idle at a normal setting when the compressor kicks on.
Drifting
Joined: Jun 2004
Posts: 1,881
Likes: 9
From: staten island ny
Originally Posted by vettfixr
but I'll add that my car is a 74 AC 4 speed car and it also uses the solenoid for antidieseling. The compressor has no effect on its workings in stock form. Also, the solenoid does not push the throttle to a given position. If you start the car with the solenoid disconnected and, once running, connect the solenoid without moving the throttle it will do nothing. It's not strong enough to move the throttle against its springs. It acts as a limiter that prevents the throttle from being closed passed a given setting.
ESU
Le Mans Master
Joined: Jan 2004
Posts: 8,295
Likes: 30
From: one night in Bangkok you are never lonely
Originally Posted by ESU
I disagree, i just installed one in my 79 because the prior one didnt work. When the a/c was turned on the idle would drop 300 or so rpms and run the risk of stalling. Soon as I installed the new one every time the a/c is turned on the soleniod shoots out and raises the idle to keep the car from stalling. Its not a limiter it actually raises the idle. I dont car what the name is , thats what it does.
ESU
ESU
