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Need some help with my 85

Discussion in 'The Garage' started by sparkyincali, Oct 11, 2005.

  1. sparkyincali

    sparkyincali Registered Member

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    Ok so I pulled the codes out of my 85 blazer and now need to know what to check.
    Code 23 short or open mixture control valve
    What does the mixture control valve and connector look like and where exactly is it ?

    code 34 Vacuum sensor or Map sensor
    Cant find anything on a vacuum sensor all just seems to relate to map sensors same as above whats it look like and what should I check

    Code 45 Rich mixture
    I am assuming this is linked to the code 23 and solenoid is dumping to much fuel or is there something else I should look for ?

    85 K5 350 700r4 Cal smog underhood smog code UJH

    I am really starting to miss having a pre smog car with only a couple of wires and vacuum hoses in the engine compartment :doah:
    It also has an msd coil which I have heard can cause some error codes although none seem related to that just thought I would mention it
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    Only one CCC code that you have that I was able to find explained for this thread:

    http://coloradok5.com/forums/showthread.php?t=141717&highlight=codes

    Obviously the codes for TBI and CCC are going to be fairly similar, but the MCS vs. injectors is a pretty big difference. Still, CCC and TBI share just about all the same sensors.

    The MCS (Mix Control Solenoid I'm assuming is what code 23 is talking about) is the typically blue plug on the passenger side front top of the carb, two wires only IIRC. The other connector on the drivers side is the TPS, 3 wires.

    In my experience (having been on multiple 1980's GM car lists in the past) the MCS is very rarely a problem. That is not to say that they can't fail, they can, but I wouldn't jump to that as a problem immediately, especially at the price they are. (or what they cost last time I checked) Really need to find a service manual that covers CCC, to see what the culprits can be of that code. Sorry, I don't have any of that.

    FYI, if you head over to thirdgen.org, they either have a forum that covers CCC, or a forum that CCC stuff is covered in. (all carbed GM cars in the US from '81-90 used CCC) Pretty much a no-no on that forum to talk about other vehicles, BUT if you don't say what you are working on other than year, you should be fine.
     
  3. sparkyincali

    sparkyincali Registered Member

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    Ok figured out the solenoid issue which fixed rich issue but I cant figure out the map sensor issue.The map sensor has a vacuum hose that runs to the carb and hooks up at the top back.I tested the poet for vacuum and there was no vacuum at idle or higher throttle.engine vaccum at idle was 15" at another port.My ? is where should the map sensor be hooked to does it hook into a full vacumm port or no
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    Sorry for the delay.

    Should be hooked up like TBI I would think, I can't imagine that is anything other than manifold vacuum.

    You say at the top back, is that up at the very top? (carb is 3 major pieces, throttle body, float bowl, and the airhorn is the top) If it's at the top, that port essentially sees no vacuum, it's a clean air feed in the cases I've seen.

    Odd that the rich condition has been fixed if the MAP sensor is hooked up wrong, no vacuum would indicate high engine load, which SHOULD dump a bunch more fuel. :confused:
     
  5. sparkyincali

    sparkyincali Registered Member

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    yeah it is hooked up on the airhorn above the throttle plates so it is getting no vacuum.I tested to confrirm and zero but couldnt find in the manual where it should be hooked up and other places I have read including the manuial were not much help.I think the rich mixture code was fixed after I fixed the mixture control solenoid plug.I am fuguring with it unplugged it was stuck open and just dumping fuel in.I am gonna try to hook it to a manifold vacuum port on the intake and see how it runs and if the code comes back
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    Report back if that solves the problem. I suspect it will. May very well be in some sort of limp mode that keeps it from referencing the MAP sensor, thus the code for just that.
     

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