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Rough Idle - learn from me

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    Rough Idle - learn from me

    I have a 91 m20 vert with low miles. Ever since i got the car It had a rough idle. The car would occasionally miss, generally be running rich, and when rolling to a stop idle would bounce. The car was dragging ass and not in a good way.

    This part of the post is dedicated to my mistakes in diagnosing the problem. I post it here so others can learn from me being ignorant.
    When i purchased the vehicle I was given a receipt for all the timing belt and water pump service being done at a mechanic. I ~assumed that all mechanical pieces in the cooling system were replaced as well. There other symptom Ignored was the radiator gauge staying cold. Needle never moved or raised (SO I thought). I found a small brass nut on the floor and immediately ~assumed this was a ground nut for the temp gauge and that was why it didn't work.

    Now at this point some of you know the problem. I didnt, at the time. So now Im going through the iterations of looking for air leaks, replacing electronics and overall just being pissed of and disappointed with the car.

    Eventually I take it to a friend with a scan tool and its right there is front of me slapping me in the face with a bad data point; car is running at 146* and not moving. Thermostat was completely stuck open. The car has been running cold. A $30 part from vatozone fixed the problem. oh and you know the temp gauge works.... >.<

    So my tips are simple to fighting a rough idle;
    1.)Don't assume anything, just because you think something is already broken doesn't mean that is not a symptom of a different problem.
    2.) If you have a newer car find a friend with a scan tool that can view live data. Buy that friend beer often. Then attack the bad datapoint

    Here is a link to Jlevie 's post. follow it or your Bentley but dont assume a damn thing about your car. Check it all, in order. Hope it helps someone, or at least give you the encouragement to know you can beat it!
    02/1992 E30 Cabrio
    02/1989 E34 535iS

    #2
    Never be ashamed to take a bite of that humble pie and ask for help. Good Post man. Thanks for sharing.

    Comment


      #3
      These are the times that justify tool purchases-
      IR temp gun: indispensable!

      Mine, last week: E46. Throws a code for secondary air pump low flow.
      Well, it's got 125k on it, these are known to fail, and it's a bit noisy,
      so I spend the $300 on parts, and go to replace them.
      The fan and valve were fine, the .67c worth of vacuum line
      that connects the valve to the switched vacuum source had hardened up and fallen off

      It happens all the time- the obvious has it's teeth buried in your nose, and you
      stubbornly refuse to believe it.

      t
      now, sometimes I just mess with people. It's more entertaining that way. george graves

      Comment

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