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Thread: High idle after driving

  1. #1

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    09-20-2016
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    Hiltons,VA
    Vehicle

    1990 Mitsubishi Mighty Max
    Engine

    I.D.K.?

    High idle after driving

    First id like to say I have no idea if this is the right place to ask these questions. Ok, so I just got a 1990 mighty max with the 2.4 engine. It had sat for almost six years, so the first thing I did was drop the tank and clean it out. (FYI the soaking in viniger trick seems to work super well) replaced fuel filter, oil and filter, air filter, and antifreeze. Then I replaced the plugs and wires. It fired up and seemed to work great. I took it for a short drive and have noticed a couple things I can't seem to figure out.

    First. It idles fine at first,but after I press the gas then let off it idles really high. No tac but if I had to guess I'd say around 2k.

    Second. It doesn't seem to ever warm up.
    Could this be a thermostat issue? I ordered a thermostat and gaskets and they should be installed by the middle of next week.

  2. #2

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    12-21-2013
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    Maurertown, Virginia
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    1990 Dodge D-50
    Engine

    4G64
    Hey, reignboy (fellow Virginian), welcome to the forum...

    You'll find out soon enough if it has a thermostat or not...sounds like it may have been removed. If the engine is running without a thermostat, it could well affect the idle. It may also need the cable adjusted. But first things first: see if it has a thermostat.

    There is also a helpful thread for trucks like yours', particularly since the truck has been sitting so long -

    http://www.mightyram50.net/vbulletin...and-do-it-ASAP
    The greatest gift you have to give to the world is that of your own self~transformation.

  3. #3

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    1990 Mitsubishi Mighty Max
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    I.D.K.?
    Thanks! I will check it out either tonight or tomorrow. Currently sitting in a math lecture lol

  4. #4

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    1990 Dodge D-50
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    4G64
    Be sure to have the thermostat bleed valve at the top. From my own build thread:

    http://www.mightyram50.net/vbulletin...ll=1#post26505

    The thermostat has an off-center positioning...sort of like a fried egg...and the housing has a beveled bottom. I figured that the thermostat needs to open on the lower end or it will hit the sensor prong, preventing the thermostat from fully opening. Not sure this is true, but if it is, this would cause the engine to run hotter than necessary. There is a little "air valve" at the 'top' of the thermostat (as it should be placed when installing) that indicates to me the proper positioning of the whole unit. Again, the frikkin' book says nothing about this. But by observing the sensor's placement (top of the thermostat housing) and the thermostat itself, this is what I concluded. I positioned it in the way that made the most sense.
    Look at the temperature sending unit, and see if it looks new, or if the rebuilder simply put old ones back.

    Be sure to look at the tag on the fire wall, to see what engine type it says your truck is (i.e. 4G64). You need that information.
    The greatest gift you have to give to the world is that of your own self~transformation.

  5. #5

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    1990 Mitsubishi Mighty Max
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    I.D.K.?
    It indeed did not have a thermostat. I put one in from my 89 mighty max and it seemed to fix the idle problem. Haven't drivin it yet because the gaskets fell apart. Once they come in I'll give an update. Thanks again!

  6. #6

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    Hiltons,VA
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    1990 Mitsubishi Mighty Max
    Engine

    I.D.K.?
    Sorry for the delay. It is functioning and I've been helping my girlfriend move. However it's only getting like 12 mpg. I had a 89 and was getting at least 30 every day. I can't imagine this is normal.
    I was thinking maybe a bad o2 sensor could cause this. Any suggestions welcome, and thanks in advance

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