Newbie with 85 Eldo issues
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Cadillac Seville / Cadillac Eldorado Forum Discussion, Newbie with 85 Eldo issues in Past Cadillac Vehicle Discussion; Let me start of by saying Ive been dragging my feet and not signing up with this forum. I dont ...
  1. #1
    ssrob is offline Cadillac Owners Member
    Automobile(s): 85 Eldorado Convertible, 84 DeVille limo, 77 Coupe DeVille
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    Newbie with 85 Eldo issues

    Let me start of by saying Ive been dragging my feet and not signing up with this forum. I dont know what took me so long!!! This is truly an awesome place for people like us to talk about the best American made cars around.

    I am the proud owner of an 85 Eldo convertible and an 84 DeVille Maloney Coach limousine, both 4.1 and never missed a beat. The 84 runs like a top and get 24 mpg on the highway. The Eldo not so much.

    It has been running quite rough and I drew the codes from the HVAC and found code 52 which I believe is an ECM error or reset. I have tried to search the site first and I cant quite find much about this subject. Also, both cars having issues with the convertor staying locked while coming off the highway. I understand it could be the TCC solenoid however I think it could be a complete error on the part of the ECM due to the solenoid function coming from the ECM. Being that the whole car runs bad and gets worse as it warms up, I would think that the ECM is shot and needs to be replaced.

    I will get to basics and perform a cylinder compression test, timing, and inspect other ignition components for failure and fuel pressure check.

    Any ideas from anyone. I want to put the "HIGH TECH" back in my HT4100. Thanks in advance for your help.

    Rob

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  3. #2
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: Newbie with 85 Eldo issues



    How old are the plugs, wires cap and rotor?

  4. #3
    ssrob is offline Cadillac Owners Member
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    Re: Newbie with 85 Eldo issues

    I am going to pull all that this weekend to see how it looks. It does sound like its running on 7 cylinders. Maybe its "retarded" so I will check the timing! LOL!

  5. #4
    the recluse is offline Cadillac Owners Connoisseur
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    Re: Newbie with 85 Eldo issues

    Quote Originally Posted by ssrob View Post
    I am going to pull all that this weekend to see how it looks. It does sound like its running on 7 cylinders. Maybe its "retarded" so I will check the timing! LOL!
    What's the mileage? Is it TBI or PFI? Look for vacuum leaks while apart, check thoroughly. I once had a vacum connection that was cracked on the underside and I had overlooked it for a month till I pulled on the line one day and only half came off with it...

  6. #5
    ssrob is offline Cadillac Owners Member
    Automobile(s): 85 Eldorado Convertible, 84 DeVille limo, 77 Coupe DeVille
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    Re: Newbie with 85 Eldo issues

    Good idea. I will check that also. What is really bugging me is the code 52. What I am more inclined to go to first is the ECM. Over the years with heat and dust really upsets electronics. So all the items that are wrong with the car could be linked direct to ECM. Also, I forgot to mention I am having issues with the fuel evap system and fuel flowing out of the charcoal canister. I read that the valve is also controlled by the ECM. I have a lot of tests to run this week.
    One test I would like to do is timing. With the electronic spark timing I read its controlled by the ECM and timing needs to be done differently than a standard external coil ignition. Any ideas if anyone has done this before. thanks again

  7. #6
    carnut is offline Cadillac Owners Master
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    Re: Newbie with 85 Eldo issues

    The code 52 only means that at one time or another the battery was disconnected. Just erase it and forget about it. The jerkyness coming to a stop related to the TCC solenoid is 98% of the time just a faulty solenoid. Easily replaced once the trans pan is off. The timing is done just like a 57 Chevy, meaning the use of an inductive timing light and the special offset wrench to loosen the distributor. The ONLY thing different is you must disconnect the green connector wire just behind the distributor to disconnect the ECM from the timing advance. The issue with "running bad" needs to be diagnosed in a logical order. First thing, verify fuel pressure is in spec under ALL driving conditions. If that means running a longer hose from the test port to the gauge so it can be taped to the windshield so be it. A car this old can have a plugged inlet filter on the fuel pickup within the tank or a weak pump from age. Been there, done that! Spark plug wire routing is critical from the cap to plugs, all retainers must be in place or the car can misfire. This car tended to wear out the distributor drive gear at low mileage and can cause rough idle and general poor performance.

  8. #7
    carnut is offline Cadillac Owners Master
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    Re: Newbie with 85 Eldo issues

    This car runs best at 12 degrees before rather than the 10 degrees timing listed on the decal. Use only A/C Delco plugs if you do change them. We have no idea the odometer mileage on either car so further reccomendations are fruitless. The ECM provides a ground to most items to control them rather than voltage so it will last a long time. Nothing you describe points to anything remotly related to an ECM replacement.

  9. #8
    the recluse is offline Cadillac Owners Connoisseur
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    Re: Newbie with 85 Eldo issues

    Quote Originally Posted by ssrob View Post
    Also, I forgot to mention I am having issues with the fuel evap system and fuel flowing out of the charcoal canister. I read that the valve is also controlled by the ECM. I have a lot of tests to run this week.
    Purge Valve.

  10. #9
    carnut is offline Cadillac Owners Master
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    Re: Newbie with 85 Eldo issues

    I agree, faulty purge valve. Or more specificly, the purge valve solenoid mounted just above the canister.

  11. #10
    ssrob is offline Cadillac Owners Member
    Automobile(s): 85 Eldorado Convertible, 84 DeVille limo, 77 Coupe DeVille
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    Re: Newbie with 85 Eldo issues

    thanks for all of the great feedback. Well, so far Ive gone down into the vacuum system and 99% of the vac hoses are soft and spongy or brittle thus making any of the systems they are linked to useless. by the way the car has 135,000 on the clock. I also noticed that the ignition wires are not AC Delco so those are going in the trash. I think when it comes to ignition, especially on GM, Porsche, and Toyota, you should go full OEM. Something about the resistance of these different parts causes issues. Still need to tap the fuel port for pressure check and pull plugs for compression. Update soon

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