Idle adjustment while in gear

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  #1  
Old 10-22-09, 04:31 PM
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Idle adjustment while in gear

1984 Ford F-150, straight six, automatic, one barrel carburetor.
Haynes says that all idle adjustments should be made while the truck is in gear. Fine. I adjust the curb idle while it is in gear. Naturally, when I take it out of gear, the RPMs go way up. What device, if any, tells the carburetor to idle down when the transmission is not in gear. I adjusted the idle control per emissions label, I adjusted the high (cold?) idle per emissions label. According to the label, once that is done, the idle will be automatically controlled at 650 RPM (guessing at that number).
 
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  #2  
Old 10-22-09, 05:39 PM
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The Idle stop solenoid is what is to be adjusted and not the idle screw on the side of the carb.
 
  #3  
Old 10-22-09, 06:24 PM
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Man, I am soooo confused at this point. Do me a favor. Go here Picasa Web Albums - Andrew - Carb screws
and look at the photos. I'm sure I know what you are talking about but please look at them and identify them for me.
Now back to you answer. So, I should disconnect the coolant temperature sensor, put the truck in gear and adjust the idle? And when I reconnect the coolant temperature switch, put the truck in park, tap the throttle it will resume a normal idle speed and kick it up a notch when I put it in gear? And thanks so much for the quick response.
 
  #4  
Old 10-22-09, 07:02 PM
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If you are having trouble with erratic or high idle speeds chances are that you have a problem in your computer system which controls your idle speed except during cold start. Many times a defective coolant temp. sensor will cause the vehicle to think it is still in cold. If I remember correctly those vehicles had a problem with the idle in the computer idle circuit that controls the idle control solenoid on the carb. You probably need a pro manual with trouble trees and/or a dedicated analyzer to test four codes.
 
  #5  
Old 10-22-09, 07:26 PM
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Here's the thing. The truck runs fine and starts fine. The idle is a bit rough but right now all I want it to do is quit stalling when I come to a light. It almost sounds as if it doesn't drop out of gear in time. I finally found a dwell/tach so I'm no longer guessing at the RPMs. he base timing is pretty close. I went over the intake manifold bolts again. I went over the engine with a propane cylinder. I replaced the carburetor/spacer gasket and the spacer/manifold gasket.
As of now, I start it, the RPM's go up for a moment and then settle down to a normal sounding speed. I let it warm for a moment, take off but unless I approach a stop very, very slowly it will stall when I stop. If the idle control solenoid controls that function, then I am either doing it wrong (which is a very good possibility) or there is something mechanical that I am overlooking (which is also a very good possibility) or both.
Right now, I would love to just find out the correct way to adjust the idle speed so I can eliminate that variable. What makes everything more difficult is I am almost deaf so it is very hard for me to detect the subtle changes that most people can pick up on and make corrections.
 
  #6  
Old 10-22-09, 07:42 PM
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There is a problem that can also cause the symptoms you describe that is in the transmission. What happens is the solenoid in the transmission does not release the lock up torque converter soon enough. It's much like driving a manual transmission vehicle and leaving it in high gear when coming to a stop without pushing the clutch. It's called chuggle, probably because it brings the engine speed down to chugging. Hope this helps.
 
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Old 10-22-09, 07:48 PM
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Yes, it feels exactly like the clutch wasn't pushed in soon enough on a manual transmission. Before I go off on another tangent though, why doesn't it release? Would that problem be vacuum related or is it electronically controlled?
 
  #8  
Old 10-22-09, 07:55 PM
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The torque converter solenoid is electrically controlled and is in the transmission. It is easily changed after pan removal. It is likely your problem.
 
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Old 10-22-09, 08:30 PM
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This is a 1984. There is no computer or electronics on it. All old school manual stuff.
 
  #10  
Old 10-22-09, 10:18 PM
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I had a van that was doing what you are describing for the transmission. Turned out a ground strap between the transmission/engine and frame was broken. Installed a new ground wire, problem solved.

Since you say there's no electronics, I dunno, maybe the kickdown cable needs adjusting?
 
  #11  
Old 10-22-09, 11:00 PM
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It's kind of old school stuff and kind of not. The coil doesn't look like the kind of coil I would call old school. Old school to me is a cylinder with a wire going from the coil to the center of the distributor cap ond two smaller wires, one from the starter relay and the other to the distributor (or something like that). Looks more like a magneto to me. The distributor has no points. Instead there is an ignition module at the bottom of the distributor. On the firewall is an engine control module. Took me a while before I figured out how to hook my tach up to it.
So there are electronics on it. But the kick down cable was something I thought about but after researching it I found no mention of a misadjusted cable causing a stall. If I had seen a bazillion posts mentioning stalling, I'd pay attention to it.
Regarding the broken ground strap, I will go over the whole vehicle tomorrow. I do seem to have an electrical problem that may or may not be related. My gas gauge doesn't work and something drains the battery in a couple of hours. The electrical problem was at the bottom of my list but maybe I'll move it up a notch.
I'd s**t a brick if it was something as simple as that.
 
  #12  
Old 10-23-09, 03:55 AM
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That setup is more of the "missing link" (although it isn't hard to find) between carburetors and fuel injection. It's almost like the TBI jobs with the throttle body that looks like a carb, but uses the central port injection.

With the computer in it and the ignition module and the two solenoids on the "carburetor thing" you have control of a number of basic functions = timing and fuel/air mixture. The solenoid on the side of the choke pull off could do a lot of adjusting all the way through the rpm range, but I imagine it is the IAC.

So, with a little assuming, you're down to a fixed (by jet size) mixture, with the loading variances handled mechanically and driven by an intake vacuum (or lack of atmospheric pressure) signal. That's the basic function of a current MAP sensor, although it does a few more things to arrive at an absolute value for the pressure. So there is a lot of common ground between the two systems.

You never know what the philosophy was behind it - whether that setup was the way of the future or the way to the future. Either way, the lucky dog with the truck now is the one who has to try to figure it out. A lot of shops won't even look at something like that, let alone try to get it to work again.

The biggest problem you have to deal with is what is old school and how many of the new school things are on it. The basic stuff, like intake leaks/vacuum have to be in order, as well as the normal maintenance items.

In your pictures, the idle stop solenoid (the allen wrench job) is going to handle a lot of the dynamics of the lower rpm range. That will take orders from the computer (control module) which is going to listen to all the sensors. The two screws a the base are for the most part starting points. If there is some reason regarding emissions, the computer doesn't like it, there will be some adjustments through the IAC/ECM anyway. From a distance it almost looks like some of what you have is redundant.

If you can't get that thing working, I believe I would get it warmed up, put your wife or someone in the cab, index the allen wrench setting on the solenoid so you know where to go back to, and set the inside screw (not the one on the fast idle for the choke - it should be completely off) at the base of the carb to a light creep forward with the tranny in drive. Then reset the solenoid setting and see how it works.
 
  #13  
Old 10-23-09, 08:34 AM
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LOL! You know, I actually understood all of that.
Ok, let me run this by you. I've been told, and I have no reason not to believe it, that if this wasn't a mutant, or hybrid system, and I were to remove all of the emmision stuff and electronics, the truck would run like crap because of all the detuning that was done in the design. If I found a regular distributor (with points) and a regular coil, disconnected the idle control and basically took it back to 100% old school, do you think it would run? And would I even be able to find pre-computerization components that would fit?
 
  #14  
Old 10-23-09, 09:35 AM
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I wouldn't say it wouldn't run, but I would say it would very difficult to do that. There are must too many unknowns. The main differences are clearly the engine management/fuel components. I'm not sure the basic configuration of the engine like valve timing, crank stoke, etc. (that sort of thing) would have been changed a lot just to make the transition to the new generation engines. Once they came out I would have to bet on a lot of changes.

It would be more of a possibility to put the engine into a truck that had the old setup and swap parts to get it back in time. I can't say I'd get into that idea too much either.

If the only problem is the stalling at an idle, I would work on that with the parts that are in it now.
 
  #15  
Old 10-23-09, 10:25 AM
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Yeah, you're right. I am going to keep my eyes open for a solid old generation straight six though.
Last night, I went back to looking at one of the first things mentioned to me. The EGR valve. I've had this thing off and cleaned it as best I can and replaced the gasket. Last night I pulled the vacuum line off and saw there was no vacuum. I opened the throttle and still no vacuum. So, I left it off and took it for a spin. It seemed a little better to me. Maybe it was just my imagination or wishful thinking but out of three stops, it stalled only once.
If I force the diaphragm back with a screw driver, it definitely has an effect. How can I make certain the valve is actually closing all the way?
And the PCV valve grommet is very loose. That I will replace today.
 
  #16  
Old 10-23-09, 11:39 AM
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Your EGR may be regulated by a solenoid or it may just be ported into the throttle.

To make sure it's not sticking use a spare vacuum line if necessary and find a constant vacuum source on the intake. Start the engine and apply vacuum to the pancake. The engine should immediately run rough and even stall. Then pull the vacuum off and the running should straighten out immediately. Do this four or five times. If it goes to rough, then back to smooth, the valve itself is probably OK. That would only leave the actuation source to be at fault if the EGR is the problem.

EGR and idle problems do go together.

If you get the valve checked out and it's OK, and you want something cheap to try. Put Sea Foam in the gas. You can get it from an auto parts store. It can really make a difference on something that's causing a problem from being gummed or varnished up.

It only takes about an hour of running time to see if it's going to change things.
 
  #17  
Old 10-23-09, 12:12 PM
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I put vacuum to the valve and nothing happened. I reached around it and pushed the pancake back with my fingers and it ran rough. I kept moving it back and forth and one of the times, the idle got smoother than it has been. Not being one to let well enough alone, I just had to do it a few more times and the idle is back to where it was. So the EGR valve could be a suspect.
I'm going to go see a friend and he lives about an hour and a half away so I will pick up the sea foam and put it in before I leave.
 
  #18  
Old 10-23-09, 01:18 PM
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If you put vacuum on the pancake port and the valve didn't open = rough running the EGR pancake is either shot or the valve is stuck tight. Since you were able to move it manually, the pancake would be shot.

Taking this farther if the actuation source was OK it would apply vacuum to the diaphragm. Since that isn't working the diaphragm is likely ruptured so when the EGR should be coming on, you have a vacuum leak instead. That could account for the stalling.
 
  #19  
Old 10-23-09, 09:21 PM
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That makes perfect sense to me. Before I go out and get a new one, could I swap the EGR gasket with a solid one to totally block both the exhaust inlet and outlet? Come to think of it, do I really need the EGR valve. Emmision laws are not an issue in this case.
 
  #20  
Old 10-24-09, 03:26 PM
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I definitely need a new EGR. I blocked it off and the engine does idle smoother. It didn't eliminate the stalling entirely. It seems to stall more often when it is warmed up. Choke adjustment and/or idle mixture I guess. But I'm getting closer and I learned alot about emission controls thanks to everybody here.
Before I retune it after blocking the EGR, the choke must be fully open, correct? I will replace the EGR but it's going to have to wait a bit.
 
  #21  
Old 10-24-09, 03:52 PM
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If the stalling is associated with a warm engine, think in terms of vacuum leak = lean mixture. With the EGR blocked off, did you disconnect the vacuum line going to it?
 
  #22  
Old 10-24-09, 05:49 PM
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Nope, forgot all about that. It's plugged now, though, and I took it out for a spin. Too short of a spin to really tell though. I'll say this, it's far, far better than it was. I can live with it. I just have to drive like a normal person instead of waiting until the very last second to stop.
There is still a leak somewhere. I believe it is probably the intake manifold. When I replaced the gasket, I did it in less than favorable conditions. I'll take the manifold off again but I'll make certain it is done right.
It is running so much better I can't wait to take it back to the former owner's house and show him. He could never get it running and he is a mechanic.
I'd like to say I fixed it but I'll have to tell him there was about six people working on it.
 
  #23  
Old 05-24-10, 06:59 AM
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FINALLY! Success!!

I spotted a truck like mine in a junkyard and it had a brand new rebuilt carb. I bought it, the new EGR valve and the new distributor it had for $50.
Came home, put the new carb on and ALL my problems went away! The carb came off a stick shift and mine is an AOD so it idles a little low but there is no more stalling at lights.
I AM pleased.
 
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