Jump to content


  • Posts

  • Joined

  • Last visited

  • Days Won


Posts posted by OldCadTech

  1. Still sounds like an air mix door problem. I went back through the post, but, since I don't subscribe to photobucket I couldn't see the pictures. The Deville used the air mix door to control the amount of air through the heater core. Even if the actuator is moving, that  doesn't mean the door is operating correctly.

    True, the tabs would eventually clog radiators and heater cores but that was over a long period of time. One year to plug a heater core is very extreme...especially since the coolant is in pristine condition.

  2. 16 hours ago, sonjaab said:


    Aint no heater valve in these ol' squarebodies!   

    3 way factory restrictor "tee" in place and temp accuator working properly.

    HVAC control and temp functions working properly.

    Just weak heat AGAIN!

    Am I missing something?



    (not my pic)


    Did you check to make sure the valve/orifice is not plugged? You can do a temp check... If the inlet is HOT and the others aren't as hot pull it out and look.

    Back flush it if everything else checks fine before you pull the core, or pull it since you had fun last time... JK :)

    Is the coolant level correct?  What is the coolant temp?


  3. Okay, now that you straightend me out on the optispark system, I was still thinking distributor at the rear of the engine, sorry.

    The optispark was not as reliable as the regular shaft driven distributor and earned several infamous names. SO, in short, replace the optispark and do the tune up. I think you'll get the smile back!!

    I'd go reputable, quality aftermarket for the optijunk (oops) Opti-spark......

  4. Sounds a lot like the fuel pressure regulator is defective or there is a restriction in the sending unit/fuel pump assembly.

    To me, the foaming of the fuel would indicate the pump is sucking air.

    Since the fuel pressure regulator is non serviceable, replaceable yes, were you disassembling the fuel rail?

    When you replaced the fuel pump did you replace the screen/filter at the pump inlet (commonly referred to as a sock)?

  5. I guess the first question I have is - has the vehicle ever had a tuneup ? The mileage would indicate a tuneup is past due. Plugs, Cap, Rotor, wires. Coil if it is burnt or the button is bad.

    Replacing the distributor seems a little extreme.

    You say you went from a tip-in hesitation to a "crumble", does that mean miss?

    There is a base timing, and the computer "controls" the timing from there. I doubt very much that the timing is off if it has been unmolested.

  6. I've always taken them out the top. Mainly because I never liked pulling transmissions. And it seemed to me like waayyy to much work to drop em out the bottom.

    I don't remember seeing the procedure in the 98 FSM (that I gave away) either, but I had been taking the engines out since '85, so I never really looked either.

    I guess the question is ... do you have access to a lift? - twin post works the best IMO but center lifts can be used... Do you have access to a "cherry picker"? The engine comes out over the rt fender.

    It is going to take some sepecial extensions and swivel sockets and it requires lifting and lowering the vehicle several times.

  7. @TedK


    This is one of the hardest codes to diagnose. We nicknamed it the 800 line cuz ALL the modules use it.

    As you probably know it can be caused by ANY module on the 800 line or any combination of modules. You have started down the right path, as checking grounds is the first step to perform.

    The parts department at the dealership I worked at would let us plug and play modules as this was the only way to determine the defective module. The codes you have are of no help as the rule of starting with the lowest code first does not apply with this 800 line malady...

    The ground I would start with is behind the drivers kick panel. Look in the FSM at the grounds section and the locations section to determine locations. 

    Personally, I would start with the pass key/security module as most of the others (except the PCM) would allow the vehicle to start but they would set a hard code and turn the light on.

  • Create New...