78 CDV won't idle down. Choke issue?
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  • 1 Post By carnut
RWD 19xx-1984 DeVille and Fleetwood,
1985-1996 Fleetwood and Brougham Forum Discussion, 78 CDV won't idle down. Choke issue? in Past Cadillac Vehicle Discussion; Ok guys, Tonight I fired up the Caddy and pulled her out of the garage. I usually turn off the ...
  1. #1
    lacville78 is offline Cadillac Owners Fanatic
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    78 CDV won't idle down. Choke issue?

    Ok guys, Tonight I fired up the Caddy and pulled her out of the garage. I usually turn off the engine after pulling the car out while I lock the door, but this time I decided to let her run a bit. When I got back in the car, I went to depress the accelerator to turn the choke off and idle it down. No luck, I then pulled the air cleaner lid and looked to see if the secondaries were stuck open, but they were closed. I went for a cruise and no dice, she is still idled high, even after shutting the engine off and restarting.

    I have to shamefully admit, I am not a mechanic. I was more of a helper at my dad's shop. After his stroke, he is in no shape to help. So it looks like it is just me, and the knowledge from this forum. I would appreciate any advice, and where to start. I will start reading up on quadrajet carburetors too. I want to tackle this problem, but I am starting from scratch as far as carburation is concerned.

    Thanks all,
    Tom.

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  3. #2
    1980coupe's Avatar
    1980coupe is offline Cadillac Owners Connoisseur
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    Re: 78 CDV won't idle down. Choke issue?

    Just floor it. My 78 would do this too and my 80. I just simply give it a nice hard tap on the accelerator and it would idle down.

  4. #3
    lacville78 is offline Cadillac Owners Fanatic
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    Re: 78 CDV won't idle down. Choke issue?

    Quote Originally Posted by 1980coupe View Post
    Just floor it. My 78 would do this too and my 80. I just simply give it a nice hard tap on the accelerator and it would idle down.
    Forgot to mention I already tried that, I will try it again later on to be certain. I will post results.
    Thank you.

  5. #4
    deVille33 is offline Cadillac Owners Connoisseur
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    Re: 78 CDV won't idle down. Choke issue?

    Pull the air cleaner up and look to see if anything may be interfering with the throttle shaft or the linkage. As the weather gets cooler this time of year critters will sometimes bed down in there at night to stay warm and sometimes bring a bedtime snack along with them.

  6. #5
    77CDV's Avatar
    77CDV is offline Cadillac Owners Master
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    Re: 78 CDV won't idle down. Choke issue?

    Sticking throttle. It happens if the car isn't driven regularly. Lubricate and adjust if necessary. Minor fix.

  7. #6
    lacville78 is offline Cadillac Owners Fanatic
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    Re: 78 CDV won't idle down. Choke issue?

    Thanks guys! I did floor the car a couple of times and then start it, no luck. I even floored it quickly a couple of times when it was running and no luck. I will pull the air cleaner and give the throttle shaft and linkage a visual inspection and lubricate it too. I really appreciate the help!

    Thanks,
    Tom.

  8. #7
    carnut is offline Cadillac Owners Master
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    Re: 78 CDV won't idle down. Choke issue?

    Never lube throttle linkage! its designed to be cleaned, never lubed. Look to see if the choke electrical wire is attached to the choke assembly on the passenger side of the carb. If it fell off, no heat will be present to release the choke. Use carb cleaner in a spray can to remove any residue around the choke. Do a search on GOOGLE to see what a quadrajet choke looks like.
    lacville78 likes this.

  9. #8
    afaia1978's Avatar
    afaia1978 is offline Cadillac Owners Member
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    Re: 78 CDV won't idle down. Choke issue?

    i have the same problem pretty often with my '79. does anyone know if upgrading to an electric choke would help any?

  10. #9
    deVille33 is offline Cadillac Owners Connoisseur
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    Re: 78 CDV won't idle down. Choke issue?

    Check those vacuum lines and the dashpots. The dashpots are to hold vacuum for a determined length of time. If there is insufficient vacuum or the dashpot won't hold the proper vacuum, it won't be able to pull the mechanisms back. This is also the reason it is not advisable to install overrated springs on the throttle return positions.

  11. #10
    afaia1978's Avatar
    afaia1978 is offline Cadillac Owners Member
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    Re: 78 CDV won't idle down. Choke issue?

    I am pretty sure it's not a vacuum issue. I recently went thru and replaced every vacuum line and fixed the mis-routed ones to the exact specs on the original vacuum diagram. The throttle does have a new spring on it though that is somewhat stiff. I will try to swap it out with a lower rated one and see if there is any change.

    ----------

    Any opinions or experience with replacing the factory choke with the newer electric ones? Do they make a difference?

  12. #11
    carnut is offline Cadillac Owners Master
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    Re: 78 CDV won't idle down. Choke issue?

    My friends 79 Sedan DeVille has an electric factory choke. I presume you guys have looked at the choke for an electrical lead to it and its getting voltage? Once warmed up, the choke relies on intake heat to keep it open.

  13. #12
    Robin Banx's Avatar
    Robin Banx is offline Cadillac Owners Fanatic
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    Re: 78 CDV won't idle down. Choke issue?

    ^^ I don't think so. An electric choke has a bi-metallic spring in it which is heated by 12V power supplied by the ignition key. As the spring heats up, it unrolls and winds the choke open. The electric heat to the choke stays on while the engine is running. I would also guess that the problem is within the choke somewhere and a loose wire is the easiest to find.

    Cheers.............R.

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