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Thread: 1984 Skylark - Idle Stop Solenoid and Valve

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    Default 1984 Skylark - Idle Stop Solenoid and Valve

    I'm posting this over here, hopefully it won't annoy anyone, but the X-Body side of the forum is VERY quiet, and I thought it might get a little more traffic here. Please just delete it if this is verboten.

    OK, so on my 1984 2.8L with a E2SE carb, I have been trying to square the emissions hose routing diagram with what I am seeing under the hood, and I think I am missing the Idle Speed Acutator. I would love to know if anyone can help pinpoint what the part number(s) of these items are, and how they ought to be connected.

    From what I can tell, this circuit should start at port H on the carburetor, and tee off before the EGR Vacuum Solenoid Valve. From there, it goes to the Idle Speed Vacuum Solenoid Valve, and Splits again, one portion proceeding through a check valve to the AIR Management Valve, while another line looks to proceed to the Idle Speed Actuator. Based on the Emissions Hose Routing diagram, it looks to me that the actuator would be controlled by vacuum, but all of the actuators I see out there seem to be electrically operated.

    Here's the underhood diagram. Please excuse the low-quality photo I grabbed from a video I had made:


    Here's the Idle Speed Vacuum solenoid Valve. You can see that one Vacuum line has tape over it. The other one in the foreground is capped. My understanding is that this valve will pass vacuum when open or block it when closed, and is operated via the electrical connector.


    And here is the spot on the throttle linkage that should (I think) have an actuator in it.


    My apologies for posting X-body stuff here, but I'm despairing of getting more than a tiny handful of eyeballs on my posts, and I'm pretty certain that all of this stuff should be quite similar to the early A-bodies.

    Many thanks,

    Tom
    Last edited by trymes; 05-01-2020 at 04:13 PM.

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    Senior Member CorvairGeek's Avatar
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    I just realized I have a FSM that may have this info in it. I'll take a look.
    Jerry

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    The '84 X car FSM (Olds) I have shows the 2.8 only having a 'throttle kicker' (solenoid), which is electrically actuated by a ground at pin 19 (through a relay) from the ECM. It gets it +12v from ECM fuse (it feed numerous other items as well).
    Oddly, the legend on the previous page calls it the Throttle Kicker Vacuum Solenoid. I haven't personally seen a GM vacuum operated one since the '65 Corvair with A/C, so I believe that is an error.



    Jerry

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    Oh, boy, as I dig into this more, what an abomination this is. It really uses vacuum!



    Jerry

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    It keeps going...



    Jerry

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    Hope this helps. I did not find an individual component section at the end of the emissions chapter like many components have.
    Jerry

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    A pic I have of a carbureted '86.



    Fuel injection couldn't come fast enough when I look at these.
    Jerry

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    Quote Originally Posted by CorvairGeek View Post
    A pic I have of a carbureted '86.



    Fuel injection couldn't come fast enough when I look at these.
    You say that, but look at the 86 model 2.8 MPFI. They are even worse than the carb in my opinion. Just vacuum lines running everywhere. Good engine? Yes. Easy to work on... NO!
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    Jerry,

    Thank you so much for these details! I have a FSM, but it's for 1981, and I can only trust it so much (plus, I didn't have it until after I posted the OP).

    Looking at the excerpts from the FSM and the photo, plus another I received from another owner, I still have a question, and I think it applies to the EGR system, too. It appears that, when the solenoid valve is energized, vacuum is applied to the kicker, but when it isn't energized, the vacuum signal from port H is connected to the vacuum signal from port A, through the check valve (Port A is also connected, on the other side of the check valve) to the primary vacuum break and the AIR management valve). Is that accurate, and what is the purpose of connecting the two vacuum circuits? A similar thing is true of the EGR valve, which has a solenoid valve that is connected to port H on one side and port C on the other.

    I made a little video while initially trying to figure this out. Note that I figure out that my Idle Speed Solenoid Valve was partially disassembled, so at 1:50 in the video when I point out a line that passes straight through with no check valve, that should be rotated 180 degrees and connect to what I refer to as "the vent" at around 2:30.

    Tom


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    Quote Originally Posted by trymes View Post
    Jerry,

    Thank you so much for these details! I have a FSM, but it's for 1981, and I can only trust it so much (plus, I didn't have it until after I posted the OP).

    Looking at the excerpts from the FSM and the photo, plus another I received from another owner, I still have a question, and I think it applies to the EGR system, too. It appears that, when the solenoid valve is energized, vacuum is applied to the kicker, but when it isn't energized, the vacuum signal from port H is connected to the vacuum signal from port A, through the check valve (Port A is also connected, on the other side of the check valve) to the primary vacuum break and the AIR management valve). Is that accurate, and what is the purpose of connecting the two vacuum circuits? A similar thing is true of the EGR valve, which has a solenoid valve that is connected to port H on one side and port C on the other.

    I made a little video while initially trying to figure this out. Note that I figure out that my Idle Speed Solenoid Valve was partially disassembled, so at 1:50 in the video when I point out a line that passes straight through with no check valve, that should be rotated 180 degrees and connect to what I refer to as "the vent" at around 2:30.

    Tom

    I didn't look to see it this may have PWM (Pulse Width Modulated) vacuum to the EGR (that kind of looks like the PWM solenoid), or if it is still purely mechanical / tempurature regulated.
    I will scan in the EGR portion of the manual next.
    Jerry

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    Thanks, Jerry. What I can?t figure out is why the EGR and Idle Speed circuits join Port H on the carb to ports A and C on the other side of the carb.

    I think I need to get the manual out and figure out what those ports do.

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    Here is the EGR section. Since there is no feedback, it isn't very extensive. It is showing using manifold vacuum which is unusual. It was usually ported vacuum.



    Jerry

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    Quote Originally Posted by CorvairGeek View Post
    Here is the EGR section. Since there is no feedback, it isn't very extensive. It is showing using manifold vacuum which is unusual. It was usually ported vacuum.
    That actually makes the rest of it make sense, I think. Ports A and C on the carb must be ported vacuum. With manifold on one side and ported on the other, the system can modulate the signal for PWM, or it can release the vacuum actuator and allow it to retract. I'll have to experiment when I get back to the car.

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