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  • April 13, 2024, 07:54:45 AM

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Author Topic: What causes carb to move to fast idle position? Choke thermostat?  (Read 4973 times)

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Offline 86Woodgrain

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Hey all, I rebuilt the stock carb about a year ago, replaced all vacuum hoses, replaced choke pull-off and choke thermostat. Used factory Carter BBD service manuals and more to rebuild the carb and it was basically PERFECT at that time.

Fast forward to this year and it runs rough and rich while warming up and refuses to go into high idle position when I do the usual press it to the floor before starting. Now it is getting cold here, like -20 C so it's definitely cold.

I haven't researched a lot yet but is it the choke thermostat that causes the linkage to move to the fast idle position? If I can get it back to going onto fast idle at cold startup I think that will fix it. The choke thermostat was new last year and I put voltage to it to test it and it does move some. I don't know how far it should move though and how fast. I think I have about 60 seconds maybe for the choke thermostat to do it's job? Not sure.

I really need to get fast idle working because I have basically parked the car for the time being while I figure it out. It's OK it's not my daily driver, fortunately.

Offline TheBirdman

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #1 on: January 02, 2022, 06:21:14 PM »
Yep, the choke thermostat pulls on a linkage that moves the choke plate, and a little cam that sticks under the throttle linkage, to bump it up for high idle. Theres some complicated adjustments you can make to adjust the fast idle separate from the choke, but the easiest thing to do is loosen the 3 screws around the ring that holds the choke thermostat on, then turn the thermostat so that it pulls the choke linkage further.
83 eagle wagon 4.0

Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #2 on: January 02, 2022, 08:12:39 PM »
Which way should I rotate it? I rotated it counter clockwise as you are facing it. I turned it until the choke was fully open when hot. I will test cold function tomorrow.

Offline TheBirdman

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #3 on: January 03, 2022, 12:23:53 AM »
I forgot, but as you twist it either way, you will see the choke blade closing and opening. Go the direction that closes it more to give it more choke and fast idle.
83 eagle wagon 4.0

Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #4 on: January 03, 2022, 01:17:37 AM »
Then I turned it the wrong way.

Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #5 on: January 03, 2022, 06:34:04 PM »
I tried turning it both ways and am not satisfied with it. I ordered a new CV195 from RockAuto, I'll just try replacing it. The car runs so bad I'm willing to just do that to see.

I suspect the spring inside the choke thermostat just isn't moving as much as it did when it was new. Like I said I put a new one on a year ago and it was great until the summer then once the weather got bad the cold start warmup got terrible and I didn't touch anything.

Offline MIPS

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #6 on: January 05, 2022, 05:16:22 PM »
The electric choke can take several minutes to move from the fully closed to the full open position. Even longer if its super cold out. When in doubt, connect the heater terminal to battery positive and hold the throttle off the cam. Depending on how clean your choke linkage is the choke plate should slowly open on its own.

Initial choke pulloff adjustment requires a cold automatic choke coil and vacuum pulling the diaphragm in. the procedure can be found on page 1J-43 of the TSM in the Eaglepedia.  https://amceaglesden.com/guide/1J_-_Fuel_Systems

Edited: Another thing I ran into this winter was that even though I washed the carb last year I found this fall as it cooled off the choke would gum up and never pull far back enough with a pedal pump to get on the Fast Idle cam. The linkage had to be cleaned before it would work again.
« Last Edit: January 05, 2022, 08:47:38 PM by MIPS »

Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #7 on: January 05, 2022, 08:54:41 PM »
Thanks for the reply, MIPS. I have the old choke thermostat which is removed and I applied 12V to it and I could see it move but not very much.

I'm wondering if that's just a "bug" of these electronic choke thermostats. I dunno. I tried to manually move the linkage but I really couldn't say if it was gummed up. I will look at the pivot points and such when I install the new thermostat, maybe hit with a little WD40 even though it's not a very good lubricant LOL.

Offline MIPS

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #8 on: January 05, 2022, 09:41:28 PM »
I *think* closed-to-open movement of the coil is about 90 degrees. Still, I heave heard of the coil getting weak after decades of cycling so it could be bad. \ :-\ /

Verify the grounding contact surface between the electric choke and the carb is clean and the carburetor is properly grounded. I don't know what replacement electric choke heater you used but I'm aware some versions do not ground through the housing but with a second terminal. Holley's do it that way.

Do not lubricate the choke linkage. If its dirty or gummy use a carb cleaner on it.
I speak here from recent experience when I had to get the Eagle home from a family event on the night of the 25th and in the -30 cold found 3-in-1 oil becomes molasses and will stick a choke completely open.
« Last Edit: January 05, 2022, 09:52:17 PM by MIPS »

Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #9 on: November 23, 2022, 09:35:23 PM »
I have lubricated the linkage before.... hmmm
« Last Edit: November 23, 2022, 09:35:43 PM by 86Woodgrain »

Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #10 on: November 24, 2022, 08:30:27 PM »
I removed the thermostat and blasted everything (linkage) with carb cleaner and put it back together 🤞

Today happened to be balmy warm, above 0, so I couldn’t tell how smoothly the linkage worked. Next week will dip back into the -15 to -21 C territory (normal).
« Last Edit: November 24, 2022, 08:32:08 PM by 86Woodgrain »

Offline MIPS

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #11 on: November 25, 2022, 04:17:23 PM »
Around 0 with a cold engine, go out in the morning, pop the hood and take the air cleaner off. The choke should still be wide open from the last time the car was driven. Push the throttle linkage down and the choke should snap shut and the high idle screw will rest on the topmost step of the cam. Open the choke butterfly with your fingers and let go, The spring tension of the electric choke if correctly adjusted should again snap it shut. If it doesn't or it's slow to shut the linkage is not adjusted or binding somewhere.

Traditionally when you cold start a carbureted engine the first cold pedal pump would set the choke full closed (and you had the initial pulloff once you had vacuum) and once the engine started you gently tapped the gas once to take it off the top cam of the high idle and it would remain on the second step until the electric choke pulled it open further, then as the electric choke operated and the coil heated up it will land on each following step when you take your foot off the gas until eventually the choke completely unloads.
« Last Edit: November 25, 2022, 04:24:48 PM by MIPS »

Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #12 on: November 26, 2022, 11:36:42 AM »
I went out this morning to see... it wasn't even cold, a mere -1C (30F)... kind of good news though...

So yesterday I put back in the factory original choke thermostat, but I had adjusted it less than I normally would have (leaner)...

I took off the air cleaner, pressed the gas from under the hood, the choke plate closed the correct amount and it did go to the fast idle cam step.

After 3-4 mins I tapped the gas and it came off fast idle. The choke plate was open a little more.

After 15-20 mins of warming up and driving the choke plate was about halfway between closed and full open position. I don't know if it opened enough as the engine was fully warm.

I will continue to experiment in the coming days, it's going to get proper cold by about Tuesday.

******
The main thing I did differently this time is I marked on the carb with the thermostat removed the two positions of the choke itself, closed and open. Then I marked the thermostat where the spring hook is hot, room temp, and cold from the freezer. I matched those positions up as my starting point. It's kind of hard to explain so I'll add a pic to help explain what I did - don't worry I do have the choke wire hooked up even though it's not in the pic.
******

My suspicion right now is that the linkage may have not been moving as freely as it was supposed to before (thanks for the cleaning tip), and I think I had the choke set way too rich. Having these new reference marks I think will help me dial it in better as I can visually see from the top outside where things should be at, at least to start.

Fingers crossed! I still have two other thermostats to try if needed but I figured I'd start with the original one first.
« Last Edit: November 26, 2022, 11:41:34 AM by 86Woodgrain »

Offline AMC of Houston

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #13 on: November 26, 2022, 04:14:14 PM »
An electric choke coil should have gone wide open much more quickly I think.  Are you getting a full 12 volts to the choke coil?
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Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #14 on: November 26, 2022, 04:38:07 PM »
I tested for 12V a year ago it was getting proper voltage.

I went out for more driving this aft and the choke plate was fully open after. Oddly I did notice a new bog off idle. It wasn’t there before. I’m not worried too much about that just yet because I’ve had that issue come and go with choke thermostat adjustments in the past.

Offline Freeagle

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #15 on: November 27, 2022, 01:33:48 AM »
The choke thermostat setting is just lining up the notch on the plastic cover to the index mark on the carburetor housing, and then going 1 notch richer. This puts the electric terminal for the choke heater at about the 1:00 position.

Then you put a long vacuum hose on the choke pull-off diaphragm and suck on it to open the choke to the initial clearance. This will determine the fuel mixture when the engine first starts, not the choke thermostat setting. Bend the linkage rod on the diaphragm to achieve a clearance between the top of the choke plate and the carburetor body with a drill bit of 0.140".

Next you lift the fast idle cam until the adjusting screw is resting on the second highest step and measure the clearance between the top of the choke plate and the carburetor body with a drill bit. This should be 0.095". Bend the rod to adjust.

Finally, you set the fast idle speed. This is done with the engine fully warmed up, the EGR vacuum hose disconnected and plugged, and the fast idle cam set to the second step. Adjust the screw to achieve 1850 RPM in neutral.

It also has what is called a sole-vac throttle positioner on the carburetor that kicks up the idle speed when the engine is cold. The electric part kicks up the idle speed up to 800 RPM in gear when the ECU is in open loop (coolant temp under 135 degrees F) and the vacuum part kicks the idle speed up even higher to 900 RPM if the air cleaner is under 55 degrees F.  Those things are helpful to have because the choke opens quickly (before the engine is fully warmed up) and the higher idle speed from the sole-vac can keep it from idling too low or stalling during that interim period.

A properly functioning and adjusted choke along with sole-vac system will start very quickly in cold weather and rev up to ~2000 RPM within a few seconds. You then tap the throttle to drop it down to ~1200 RPM, put it in gear, and drive away. The choke opens quickly, so it'll drop off the fast idle cam within a couple minutes, probably before the engine temperature gauge even starts to move. Then it'll be just the sole-vac holding it at 800-900 rpm in gear. The sole-vac will release the throttle down to 600 rpm curb idle only after the engine and the air cleaner are warm enough.
« Last Edit: November 27, 2022, 01:41:13 AM by Freeagle »
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Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #16 on: November 27, 2022, 11:59:31 AM »
The choke thermostat setting is just lining up the notch on the plastic cover to the index mark on the carburetor housing, and then going 1 notch richer. This puts the electric terminal for the choke heater at about the 1:00 position.
I can confirm that using the notch on the thermostat housing is not an option anymore on mine at least. Perhaps the spring is not as strong as it once was? I have to ignore the mark on the thermostat to set it correctly it seems now.

I have set my choke initial setting, pull-off, and fast idle correctly using the specs in the carb rebuild sheet / underwood decal. In tinkering with it I did alter the fast idle screw setting, which I will correct in the coming days when I know if the thermostat is actually opening/closing when it should. The fast idle is very close right now anyway.

It also has what is called a sole-vac throttle positioner on the carburetor that kicks up the idle speed when the engine is cold. The electric part kicks up the idle speed up to 800 RPM in gear when the ECU is in open loop (coolant temp under 135 degrees F) and the vacuum part kicks the idle speed up even higher to 900 RPM if the air cleaner is under 55 degrees F.  Those things are helpful to have because the choke opens quickly (before the engine is fully warmed up) and the higher idle speed from the sole-vac can keep it from idling too low or stalling during that interim period.

A properly functioning and adjusted choke along with sole-vac system will start very quickly in cold weather and rev up to ~2000 RPM within a few seconds. You then tap the throttle to drop it down to ~1200 RPM, put it in gear, and drive away. The choke opens quickly, so it'll drop off the fast idle cam within a couple minutes, probably before the engine temperature gauge even starts to move. Then it'll be just the sole-vac holding it at 800-900 rpm in gear. The sole-vac will release the throttle down to 600 rpm curb idle only after the engine and the air cleaner are warm enough.
This is the first time I've heard of the sole-vac being used during warmup, does that apply to 1986 models? To my knowledge Sol-Vac was only used to bump up idle for A/C or rear defrost usage. My Sole-Vac has been unplugged for 2 years and I'm sure was non-functioning before that.
« Last Edit: November 27, 2022, 12:00:56 PM by 86Woodgrain »

Offline MIPS

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #17 on: November 27, 2022, 12:48:04 PM »
Sol-Vac is also operated by the computer through the Idle Control Relay (for the solenoid half). On a hot start the computer will engage the sol-vac for 15-45 seconds to allow the charcoal canister to purge and force fresh gas into the lines to purge any vapor. When the engine is cold it will also operate the sol-vac at a high idle to accelerate warmup, then release and back off the timing once the CTS and TAC are satisfied.

In all the Sol-vac provides TWO different high idle positions. One from the vacuum kick which is also computer controlled and one from the solenoid which is computer AND accessory controlled. When you adjust any of the idle screws they have to be done in sequence as per the TSM because one affects the other.

As I discovered a few months ago if the computer sees the RPM's fall too low or become inconsistently low (from say a bad TACH- connection) it will also engage the sol-vac to hold the idle above curb RPM until the signal it receives settles down because it thinks you are about to stall.
« Last Edit: November 27, 2022, 12:53:33 PM by MIPS »

Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #18 on: November 27, 2022, 01:17:45 PM »
I learned something new today. Well the proper setting of the sole-vac looked complex so I left it alone (unplugged) when I rebuilt the carb. I need to fix that.

Offline AMC of Houston

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #19 on: November 27, 2022, 05:46:47 PM »
Setting the Sol-Vac is also part of the IS-12e Service Letter procedures.  Want a copy?
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Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #20 on: November 27, 2022, 07:17:12 PM »
Setting the Sol-Vac is also part of the IS-12e Service Letter procedures.  Want a copy?
No I'm sure I have a copy somewhere. I followed all the directions for setting timing, idle, etc when I rebuilt the carb 2 years ago. I figured the Sole-Vac was not needed so I left it unplugged. The procedure seems complicated for setting it correctly. I guess I could try just plugging it back?? Roll the dice? Or not?

Offline MIPS

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #21 on: November 27, 2022, 08:27:39 PM »
Plug it back in. The worst you get is it's stuck on all the time because something else is wrong.

Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #22 on: November 27, 2022, 08:40:57 PM »
Plug it back in. The worst you get is it's stuck on all the time because something else is wrong.
I replaced all vacuum lines, made sure they were going to the right place. Replaced the temp sensor in the air cleaner (that was very difficult to find NOS part with correct temp rating), replaced the vacuum temp air switch thing in the manifold under the carb, etc. I have done everything I can to get the car as close to 100% factory fresh as possible in terms of configuration, except my brain :censored: over the Sole-Vac theory of operation.

I am quite confident nothing else is wrong. I even fixed the EGR and it is operational.

As an aside, what a mish-mash of electronics and mechanical stuff eh? This awkward stage between straight up simple carb and fuel injection. I know I'm close to getting it correct again. Between the choke thermostat and the Sole-Vac I will hopefully be set soon.

The manual choke kit that I bought arrived this morn. I'm going to leave it sealed in the box with the hopes that I don't actually need it so I can return it. Fingers crossed LOL

Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #23 on: November 28, 2022, 12:11:29 AM »
Setting the Sol-Vac is also part of the IS-12e Service Letter procedures.  Want a copy?
FYI no need to email it to people, it’s available online @ http://amceaglesden.com/guide/November_1987_-_IS_12E_-_Idle_Speed

Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #24 on: November 28, 2022, 12:33:16 PM »
OK next day update. A little colder today, -7C or 19F.

I connected the SoleVac vacuum line and electrical connector. Pressed gas, choke snapped closed just like it should, car went to fast idle cam. Let it warm up for 5 mins, it came off fast idle.

Went for a ~15 min drive, came back the throttle cam thing is back to normal spot (not fast idle which I knew) and again the choke plate is not open fully yet, it opened maybe 1/3 of the way (see pic below).

I'm hoping to get the engine fully warmed up later today to check the choke plate to see if it fully opens. Also, I'd like to re-set the fast idle speed and stuff. I'm quite sure the current fast idle speed is too slow but that's easy to fix.

I can't actually tell if the SoleVac did anything in my short drive today. When I came back I tried turning on the headlights and the rear defrost and the RPM didn't change. So yeah.

I think I'm on the right track, but I also think I need to turn the choke thermostat back a notch (leaner) and try again tomorrow. I don't think the choke plate is opening up quickly enough that's why I think I need to turn it leaner provided it still fully closes when cold.
« Last Edit: November 28, 2022, 12:35:04 PM by 86Woodgrain »

Offline MIPS

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #25 on: November 28, 2022, 05:07:01 PM »
It's -7 here right now as well and the car has been sitting all day so I can replicate the results when I drive home in two hours.

Edited: Because the Carter 2-barrels are so similar to eachother in how they are adjusted, I have in the past used a Mopar training video to assist in how the feedback 2bbd's are also adjusted. Among the things that are similar are choke and fast idle adjustments, though they don't use an electric thermostat to open the choke.

https://www.youtube.com/watch?v=nBtqTbGu2eU
« Last Edit: November 28, 2022, 05:31:27 PM by MIPS »

Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #26 on: November 28, 2022, 05:30:37 PM »
MIPS, I'll watch that video tonight.

Alrighty... update time again...

The choke plate was fully open after my longer 20-30 min drive, so I'm not worried about that for now. I did move the thermostat ~2mm to the lean side for tomorrow morning test purposes (to see if the choke opens faster after cold startup).

I hooked up a tach tool, set the fast idle to 1750 rpm (firewall decal says 1850 +/-100 so I'm good) with EGR line plugged.

I set the curb idle with solvac disconnected to ~590 rpm (spec is 600 rpm +/-50)

I tried to set the SolVac but it did not hold vacuum. Went to my parts car, grabbed that one, it did hold vacuum. So I hooked it up and set the vacuum SolVac high idle to 750 rpm (spec is 800 rpm +/- 50).

BUT... I could not get the electrical side of it set for the life of me. I put 12V from battery to the unit and it wouldn't extend. I tried opening the throttle to let it extend and it just wouldn't.

So I almost had it guys. I'm not sure if I did something wrong or if part of the SolVac could be broken? Honestly I felt the instructions for that step was a little unclear.

When I turned the car back on when I was done, everything hooked up right, the car went to the increased idle for 60 seconds (I timed it), so that must have been for the EVAP purge. It did it again when I got home I restarted, same thing.

I turned on the headlights, no RPM change. I turned on the rear defrost, no RPM change. So the 12V bump from the SolVac doesn't work but I think the rest of it is fairly well sorted now. Eventually I will need to fix that but I guess it's not really too urgent.

As an aside, after the car sits overnight I have to pump the pedal quite a few times while cranking for it to fire up. I'm not super worried yet about that, once I get the choke and SolVac fixed I may research that. When I rebuilt the carb 2 years ago I would only need one or two pumps in the cold for it to fire. Who knows, after setting the speeds today that may help in the morning!! Fingers crossed. I feel like I'm making progress though.

I recorded today's startup, listen for how many times I pump it - https://youtu.be/71mYMJqy59g - the fast idle was WAY too low so that will be fixed with tomorrow's cold startup.
« Last Edit: November 28, 2022, 05:36:58 PM by 86Woodgrain »

Offline MIPS

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #27 on: November 28, 2022, 05:38:46 PM »
Verify continuity or a low resistance between the Sol-vac wire and the metal bracket used to attach it to the carb. If there is no continuity either the wire or the solenoid is open. Also if you do not have a good ground between the carb and the manifold that will in theory cause the sol-vac AND the thermostat to not work properly. Some of the aftermarket kits include a ground strap but normally the four bolts holding the carb down should be enough.

For cold starting I've never needed more than one pump, even in -30. Here's another handy (thought probably really obvious) Mopar video - https://www.youtube.com/watch?v=8wZvZgYCG7Q

If you were closer here in central British Columbia you would be more than welcome to drop in and I could spend some time looking over the carb and adjustments. I've done it enough myself I got no issues dialing it in for someone else having trouble.
« Last Edit: November 28, 2022, 06:10:20 PM by MIPS »

Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #28 on: November 28, 2022, 07:08:57 PM »
I edited my post above FYI in case you didn't see it all.

Good idea, I will check for continuity. I know the Sole-Vac from the parts Eagle was pretty dirty and I didn't clean it up before putting it on.

Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #29 on: November 28, 2022, 07:09:46 PM »
Is there a document from the TSM or elsewhere that outlines all the conditions when the SolVac operates? I looked in Eaglopedia that is my usual go-to source but didn't see full theory of operation.
« Last Edit: November 28, 2022, 07:29:19 PM by 86Woodgrain »

Offline MIPS

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #30 on: November 28, 2022, 08:43:46 PM »
Okay, for your reference, here I am with a cold engine and one pump on the pedal. Choke is closed and the throttle is sitting at the top of the high idle cam.




Here is the same carb after 30 minutes of driving. The choke has unloaded completely and is being held open by the thermostat.




In neither set of the photos was the engine running, so there is no pull-off.
Here is also my thermostat. I cannot remember if I scribed the line in the housing or if that was there already but you can see how mine is positioned relative to the marks on the casting.
(ignore the unplugged wire. I did that so you could better see things)



Here is what the same carburetor, fully adjusted, will do on a cold start, choke closed and with a completely empty bowl. Note the throttle tap to pop if down to the second cam step.
(link is timestamped to 56:06)

https://youtu.be/FB6MZLUBskQ?t=3366

Quote
Is there a document from the TSM or elsewhere that outlines all the conditions when the SolVac operates?
In detail is is not listed however it is described as part of the "Idle Control System" at http://amceaglesden.com/guide/1J_-_Fuel_Systems on page 1J-101.

In short:

-The vacuum kick is only controllable by the computer using the Vacuum Switching Valve, or VsV. The computer can use it to extend the pushrod so that the solenoid idle kick will engage on its own.
-The solenoid idle kick is controlled by the Idle Speed relay in addition to the rear defroster, air conditioning and headlights using a group of diodes to prevent current backflow.
-The solenoid idle kick is not strong enough to extend the pushrod by itself against the tension of the throttle return spring. You need to either open the throttle slightly or use the vacuum side to extend it.
-The solenoid idle kick can remain on for an indefinite amount of time and the coil will not burn out

A Sol-vac with a vacuum leak cannot be operated by the computer on its own.
A sol-vac with a bad solenoid will not maintain a high idle for accessory loads/the computer and is more likely to stall at curb idle.
« Last Edit: November 28, 2022, 08:46:01 PM by MIPS »

Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #31 on: November 29, 2022, 11:15:00 AM »
Thanks for the help guys! Thanks for the offer to help in person MIPS but that's too far to go in my jalopy LOL

Update, today was -11C (12F) upon first cold start this morn. I simply pumped the gas twice and then cranked, although I looked under the hood after the first pump to check the choke valve (it was closed), the thing did fire up after cranking for about 7 seconds straight. Not bad, I guess I was too impatient with the pedal pumping and cranking before. I even think I could get away with one pump of the pedal and then crank in the future, we'll see, I will experiment.

I feel like my choke thermostat issue is resolved at this point.

The one thing that was very different today is that the car was on a higher idle mode for my whole city drive of about 30 mins. The fast idle cam was off, it seemed to be 100% on the elevated idle due to the SoleVac. It's strange having the higher idle when cold, I haven't experienced that before. I kind of expected the higher idle but I didn't expect it for my whole drive. I thought it would go away after 5-10 mins but I guess not.

The way I read the SoleVac operation is I might have this elevated idle all winter long, because it says if the air temp is below +13C it will give vacuum assist to the SoleVac and bump idle up. Page 1J-38 from that link MIPS posted.

UPDATE: I put it in the garage and popped the hood. The idle was still elevated and when I looked the engine hadn't come off the very top step of the fast idle cam just yet. Now I suspect the choke thermostat is not coming off fast enough, even though it is working. I am going to think about it but I might swap in one of the other thermostats I have... hmm....
« Last Edit: November 29, 2022, 02:13:48 PM by 86Woodgrain »

Offline MIPS

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #32 on: November 29, 2022, 02:16:55 PM »
If the air cleaner temperature is too cold (TAC switch) that will make the computer hold a high idle until the air cleaner warms up. Closed loop and curb idle isn't allowed until the coolant switch and the TAC are satisfied. The TSM section 1J link above lists this as one of the multiple open-loop modes near the end of the chapter. The idea is that doing so runs the exhaust manifold hotter and the warm air diverter will be open, so the engine will be pulling warm air in from around the hot manifold and not the front of the car.
This whole time, the choke thermostat is independently controlled. IIRC the schematic says the electric choke is operating as long as you have oil pressure, so if you were wondering, nothing I said above would affect the operation of the choke.

Here's a fun experiment. Run the engine until warm, then disconnect and plug the line to the warm air diverter actuator. If it's really cold out the engine in short order will bump the idle after a few minutes. Now go for a drive and try accelerating. Every time you give that poor carburetor a blast of air the engine will absolutely fall on its face.
« Last Edit: November 29, 2022, 02:20:34 PM by MIPS »

Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #33 on: November 29, 2022, 02:31:30 PM »
Is this where I admit that the pipe from the exhaust manifold isn't 100% connected to the air cleaner due to constantly taking it off and testing? I'll hook it up tight.

Man there are so many things that need to be just right to make this carb work I can understand why my brother keeps telling me to just swap it with a Motorcraft LOL but I'm up for a challenge instead! If it's all fixed right then it should run great.

I checked for continuity on the SolVac 12V and it was good.
« Last Edit: November 29, 2022, 02:35:26 PM by 86Woodgrain »

Offline MIPS

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #34 on: November 29, 2022, 02:36:34 PM »
That's an easy mistake.  The challenge is installing and removing the air cleaner a dozen times and not totally mangling the end of the pipe, or in my case, getting the pipe on but not noticing the actuator had become unhooked.   :P

Quote
I checked for continuity on the SolVac 12V and it was good.

Weird. Okay for our sanity and because it's two screws take the Sol-Vac off and try powering it directly from the battery. Is the pushrod still not extending and latching?
« Last Edit: November 29, 2022, 03:04:09 PM by MIPS »

Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #35 on: November 29, 2022, 04:26:39 PM »
I took the SolVac off, tried to clean it all as best I could. I pulled the rubber dust boots back and sprayed a little WD40 in there and worked it back and forth to try and make sure it is able to move if it wants to.

After doing that, it's a little sluggish to extend using vacuum. Doh, it may be a bit flaky there I'm not sure time will tell. I can't see how lubing it and operating it manually would cause that to happen.

So I took it right to the battery and when 12V is directly applied it moves a tiny bit and stops the thing from going back, when I put it back on the carb (car off) and apply 12V it basically stops the rod from moving in any direction. So with 12V applied car off I tried screwing in the end adjuster but in the end it bottomed out and won't go out further. I tried pushing and pulling on the adjuster screw at the end and it won't budge at all with 12V applied.

I also tried moving the throttle linkage open to give the SolVac a chance to extend with 12V directly applied and it just seems to stop where it is, it doesn't extend out any further.

I feel today like one step forward, two steps back.
« Last Edit: November 29, 2022, 04:27:17 PM by 86Woodgrain »

Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #36 on: November 29, 2022, 04:36:11 PM »
I applied 12V and just keep tightening that screw again, it seemed to really bottom out.

I can confirm without 12V the thing moves in and out freely by hand. It does push forward to a point when 12V is applied, but even with the throttle held open it will not ever go to a point to ever boost the throttle above idle. It would need a combination of vacuum applied AND 12V to ever get far enough IMHO. The vacuum side can push the idle up but not 12V alone.

Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #37 on: November 29, 2022, 04:50:32 PM »
Well I think we should just forget about the 12V SolVac now. I think it's totally buggered, the screw doesn't screw anything in or out. I kept turning it in when I felt resistance since I had nothing to lose. Oh well.
« Last Edit: November 29, 2022, 04:55:22 PM by 86Woodgrain »

Offline MIPS

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #38 on: November 29, 2022, 05:06:16 PM »
Actually that all sounds good. It only moves the pushrod at most 1/8". It only needs to open the throttle a tiny amount.

Gleebledorf can explain it better and he has more detailed instructions on testing https://gleebledorf.com/solvac.html


Before you pull all your hair out and get more frustrated, reset the idle adjustments per the TSM since you bottomed out the solenoid adjustment screw and lets leave it alone. This won't affect the choke and you can continue to run the rest of the winter without it making your life miserable. This can be dealt with when it's warmer out. (you can also mail the Sol-vac to me and I'll test it for you. I don't mind. :) )

Actually, now that I remembered Gleebledorf exists, he has a whole page dedicated to your original question which was the electric choke. His whole site might make your browser complain it's insecure but he probably forgot to renew his certificate again.  https://gleebledorf.com/choke.html
« Last Edit: November 29, 2022, 05:21:47 PM by MIPS »

Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #39 on: November 29, 2022, 05:58:45 PM »
Actually that all sounds good. It only moves the pushrod at most 1/8". It only needs to open the throttle a tiny amount.
It doesn't move enough to even reach the Sole-Vac vacuum adjustment screw. In other words it used to move a tiny bit before I wrecked it but it was never enough to bump the idle up even if I opened the throttle so it had room to extend.

I had seen those articles a long time ago, I will look them over again.

I did doubly-check the curb idle and SolVac vacuum idle speeds again today, they are OK.

I think I need to shop for a replacement SolVac. I shot a short video during my work this afternoon, I will upload it and post back so you can see exactly what I'm trying to describe (I hope LOL).

Edit: Video is uploading now, link is @ https://youtu.be/zJNPljYjwA0
« Last Edit: November 29, 2022, 06:00:17 PM by 86Woodgrain »

Offline Illeagle1984

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #40 on: November 29, 2022, 06:50:06 PM »
I offer my used sol-vac if you'd like it, and any other emissions parts I removed from IllEagle.  MCU, complete harness, solenoid bank.  I don't want to ever use it, but I can't bear to throw away that kind of stuff...
It's getting crowded down here:
1973 Ford Mustang "Rustang"
1984 AMC Eagle Sedan "IllEagle" 183k
1984 AMC Eagle Wagon "Eagle 2"
1996 Cadillac Eldorado 178k
1998 Oldsmobile Eighty-Eight 239k
2002 Cadillac Eldorado Doral Edition
2005 Chevrolet Silverado 1500 179k

Offline MIPS

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #41 on: November 29, 2022, 08:55:45 PM »
Edit: Video is uploading now, link is @ https://youtu.be/zJNPljYjwA0
Give me a few hours and I'll go get a video cooked up for you. From what I see it looks fine but I'll make something you and anyone else can compare with.

Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #42 on: November 29, 2022, 09:41:50 PM »
Now that I’ve been thinking about it I’m mostly wondering if you apply 12V to your SolVac does it actually push out far enough to bring the car above idle? You’d have to manually opene the throttle. Mine doesn’t come out far enough to bump idle even when I hold the gas open.

Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #43 on: November 29, 2022, 09:46:39 PM »
I offer my used sol-vac if you'd like it, and any other emissions parts I removed from IllEagle.  MCU, complete harness, solenoid bank.  I don't want to ever use it, but I can't bear to throw away that kind of stuff...
I may take you up on that. Do you have a way to vacuum test the SolVac? Otherwise I may be interested in the CTO valve with the vacuum ports on it, the temp sensor on the back of the air cleaner and that’s basically it. I’m not sure if the vacuum thing on the intake can be removed without a leak?

Offline MIPS

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #44 on: November 30, 2022, 12:55:47 AM »
Here. Hopefully this is detailed enough to explain what you should be seeing.

https://www.youtube.com/watch?v=9i-lUwsrDNk
« Last Edit: November 30, 2022, 12:56:27 AM by MIPS »

Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #45 on: November 30, 2022, 03:53:56 PM »
Here. Hopefully this is detailed enough to explain what you should be seeing.

https://www.youtube.com/watch?v=9i-lUwsrDNk
Thanks, great explanation! On mine I can't duplicate that because my SolVac isn't near the screw even when fully warm, fast idle cam completely off.

Offline MIPS

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #46 on: November 30, 2022, 04:20:52 PM »
Yep. Time for a swap then.
I've listed a Mopar and Borg Warner part number in the description.

Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #47 on: November 30, 2022, 04:26:03 PM »
Thanks. Funny both of mine are the same in terms of how far or not far they stick out with 12V applied.

For reference here's a copy and paste so I can look it up later
Quote
Defective Sol-Vac units (open coil or bad diaphragm) should be replaced. Replacement part cross-references I know of are:
Mopar: 83500342
Federal Mogul/Borg Warner: 213-245

Offline 86Woodgrain

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Re: What causes carb to move to fast idle position? Choke thermostat?
« Reply #48 on: December 27, 2022, 11:44:34 PM »
Update: I have not been able to drive my car recently due to a tire issue and doing some tinkering on it.... but I have some exciting news!

I contacted the seller on eBay with the SoleVac unit for sale in the USA and they after a week or so enabled shipping to Canada. So I was finally able to buy it!! Woohoo, it was kinda pricey at $103 Metric Dollars after all is said and done but that will be a new NOS part so yay. The smarter thing to do would be to put that money toward EFI swap but hey I'm trying to keep things original, I'm a little weird like that.

Next up I really need tires, and I need to drop the gas tank and replace the sending unit with one that is accurate. Install those mudflaps I mentioned in the other thread and then I can get back to tweaking the choke! I haven't actually got much done on the car in the last little bit but hopefully in the next 2 weeks I should be able to make some progress again.
« Last Edit: December 27, 2022, 11:45:40 PM by 86Woodgrain »

 

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