Ok i finally received my service manual, togheter came some answers...
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500, 472, 425, 368 Discussion, Ok i finally received my service manual, togheter came some answers... in Cadillac Engine Technical Discussion; Hi all, specially to Deville33 and BruceRoe. Well, today i received the service manual for the 1977-78 cadillacs, first let ...
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    gornati's Avatar
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    Ok i finally received my service manual, togheter came some answers...

    Hi all, specially to Deville33 and BruceRoe.

    Well, today i received the service manual for the 1977-78 cadillacs, first let me tell you the material is great, i only take a quick look overall is very nice.

    I took most of my time trying to find out wich one is exactly my car, and then i found out my car is a California car, why? because looking into the EFI VACUUM DIAGRAMS i was able to figure it out.

    Well, this is the California diagram:



    Now lets get to know what is wrong and why and what happens?? this one you will have to help out.

    this is the first problem i found:



    The AIR PUMP DIVERTER VALVE, what is the function of this part?

    The distributor TVS is supposed to have 3 outlets, mine only have 2, thats why one of the vacuum lines from the "T" have a screw on it?!?

    I will continue with the other problems.

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    Re: Ok i finally received my service manual, togheter came some answers...

    Second problem i found is that the distributor vacuum actuator is not connected in his own solenoid and it is connected in the EGR SOLENOID VENT. like the picture bellow:



    Now what this can cause?

    Could this be the reason my idle is sooooo high when the engine is cold?


    So far thats all that i could found wrong, now with the service manual i am sure it will be much more easy to diagnose the problems.

    Appreciate any replies

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    deVille33 is offline Cadillac Owners Connoisseur
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    Re: Ok i finally received my service manual, togheter came some answers...

    Well, I'm not familiar with the FI cars, but what you should do is purchase some new vacuum hose and correct the connections you find are incorrect. It appears the PO or someone who worked on the car didn't know enough about the system to properly connect everything and just plugged it in where it seemed to fit. If that's the case, it is a wonder the engine runs at all. Get yourself a vacuum tester, like a MightyVac, so you can test the vacuum controls and replace those which don't operate as they should. You should find this information in your service manual.
    Take the time to read the manual. There is a wealth of information in there which will explain the system and how it functions. Once you understand this you can explain it to anyone who runs into this same problem.
    Oh yeah, I think the diverter valve is supposed to redirect the air coming from the AIR pump which I believe is supposed to send air to the catlytic converter or the exhaust manifolds depending on how your emissions system is set up. This is to aid in the burning of exhaust gasses.

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    Re: Ok i finally received my service manual, togheter came some answers...

    Quote Originally Posted by deVille33 View Post
    Well, I'm not familiar with the FI cars, but what you should do is purchase some new vacuum hose and correct the connections you find are incorrect. It appears the PO or someone who worked on the car didn't know enough about the system to properly connect everything and just plugged it in where it seemed to fit. If that's the case, it is a wonder the engine runs at all. Get yourself a vacuum tester, like a MightyVac, so you can test the vacuum controls and replace those which don't operate as they should. You should find this information in your service manual.
    Take the time to read the manual. There is a wealth of information in there which will explain the system and how it functions. Once you understand this you can explain it to anyone who runs into this same problem.
    Oh yeah, I think the diverter valve is supposed to redirect the air coming from the AIR pump which I believe is supposed to send air to the catlytic converter or the exhaust manifolds depending on how your emissions system is set up. This is to aid in the burning of exhaust gasses.
    Regarding the diverter pump thats what i though too, but i think they disable the emmissions control, as in WA it is not severe as in CA, and as i heard this would make very diffciult to run the car in a cold morning, they have a lot of snow in WA.

    Now what i want to know is why there is a vacuum line in the distributor?
    What it does?
    What happens if we simply disconnect it?

    Thanks

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    deVille33 is offline Cadillac Owners Connoisseur
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    Re: Ok i finally received my service manual, togheter came some answers...

    When you step on the gas pedal you increase your fuel flow. In order for your ignition to keep up with the increase of fuel, it has to start sooner. If it stayed the same, the resulting conditions wouldn't support combustion and the engine would stall. Another result from stepping on the pedal, your vacuum signal drops. Your distributor is controled, in part, by the vacuum motor on the side of the distributor. When the signal drops, the motor releases a plate in the distributor which moves the pick up forward and the point of ignition occurs earlier.
    There is another mechanism in the distributor which aids to advance of ignition, the centrifical advance. The centrifical advance only starts advance after the distributor increases in speed. You can change it's curve by changing the weights.
    I'm probably getting too far into it. You can read about it it your shop manual.

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    Re: Ok i finally received my service manual, togheter came some answers...

    Quote Originally Posted by deVille33 View Post
    When you step on the gas pedal you increase your fuel flow. In order for your ignition to keep up with the increase of fuel, it has to start sooner. If it stayed the same, the resulting conditions wouldn't support combustion and the engine would stall. Another result from stepping on the pedal, your vacuum signal drops. Your distributor is controled, in part, by the vacuum motor on the side of the distributor. When the signal drops, the motor releases a plate in the distributor which moves the pick up forward and the point of ignition occurs earlier.
    There is another mechanism in the distributor which aids to advance of ignition, the centrifical advance. The centrifical advance only starts advance after the distributor increases in speed. You can change it's curve by changing the weights.
    I'm probably getting too far into it. You can read about it it your shop manual.
    All right, after all i think i found my problem.

    First:
    My actul TVS (Thermal Vacuum Switch) has only 2 fittings, i cant take a picture of it, but believe me, only have two ports, as my car being a california car, it is supposed to have 3 like this one:

    http://www.napaonline.com/Search/Det...001_0198980915

    That why my distributor is wrongly connected and the air pump diverter valve had a SCREW closing the vacuum line.

    And of course thats why only when the car gets very hot it stop stalling, because the Valve opens and the vacuum starts to works with the distributor.

    What i need? in my personal opinion i need to replace the TVS Switch, re-route the vacuum lines and i am good to go.

    Now the only problem i will only be able to go to the USA by the end of the year, i would never find this part here in Brasil:
    http://www.napaonline.com/Search/Det...001_0198980915

    And as there is nobody selling one out of ebay i am kind of screwed...

    If anyone have one of those for sale, in good working condition, i will gladly pay using paypal.

    Deville, what do you think about my thinking? this might be my problem?

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    Re: Ok i finally received my service manual, togheter came some answers...

    Your TVS is supposed to normally route ported vacuum to the HEI advance, so the HEI only gets advance as the throttle opens. But if the engine gets too hot, the TVS switches the HEI to direct manifold vacuum, to speed up idle. You could just connect the HEI hose directly to one of the TVS hoses that go to the throttle body. The correct one would be ported vacuum, though the engine might run better connected to direct manifold vacuum.

    I believe the TVS is common to all cars, not just EFI, and many years & brands as well. So it may not be hard to find. Bruce Roe

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    Re: Ok i finally received my service manual, togheter came some answers...

    Quote Originally Posted by BRUCE ROE View Post
    Your TVS is supposed to normally route ported vacuum to the HEI advance, so the HEI only gets advance as the throttle opens. But if the engine gets too hot, the TVS switches the HEI to direct manifold vacuum, to speed up idle. You could just connect the HEI hose directly to one of the TVS hoses that go to the throttle body. The correct one would be ported vacuum, though the engine might run better connected to direct manifold vacuum.

    I believe the TVS is common to all cars, not just EFI, and many years & brands as well. So it may not be hard to find. Bruce Roe
    Im working right now, i will do that as soon as i get home.

    Meanwhile i found the right part in AMAZON . com it is the BORG WARNER EC906.

    I will do the tests at home and post it here later on.

    Thanks again BRUCE!

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    Re: Ok i finally received my service manual, togheter came some answers...

    By any chance do you know what the M D C means on the schematics for the TVS valve?

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    Re: Ok i finally received my service manual, togheter came some answers...

    I would think

    M- Manifold
    D- Distributor
    C- Carburetor

    Because this was a general part that started being produced in the age of carburetors, the designations never changed once they started using throttle bodies.

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    Re: Ok i finally received my service manual, togheter came some answers...

    well that could be right

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    Re: Ok i finally received my service manual, togheter came some answers...

    Definitely right!

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    Re: Ok i finally received my service manual, togheter came some answers...

    Is the barb snapped off the TVS? Maybe that's why it looks like it only has two ports instead of 3.

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    Re: Ok i finally received my service manual, togheter came some answers...

    Quote Originally Posted by Brother_B View Post
    Is the barb snapped off the TVS? Maybe that's why it looks like it only has two ports instead of 3.
    What is Barb?

    I purchased i new TVS valve from amazon, i will be receiving the new one, tomorrow and changing asap.

    How can i test the solenoid?

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    Re: Ok i finally received my service manual, togheter came some answers...

    A barb is the thing that you connect the vacuum lines to by pushing the vacuum hose onto the barb. It is the same as a port. I think when you say solenoid, you are talking about the "speed controlled spark advance system". I don't know how to test it. In my older '72, it is supposed to close and shut off the vacuum advance to the distributor at speeds below 33 mph. In my car, the solenoid would be closed at speeds below 33 mph. So one test would be to test for electrical continuity when the car is just idling. I don't know a way to test it when you are driving at 33 mph, but about 33 mph, the switch (solenoid) should open, if your car is the same as mine. Hopefully you already found this in your service manual.

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