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    Rough Idle?

    What are things that cause a rough idle? Shakes the whole car at lights and stop signs. Kinda pisses me off so I want to fix it. I have new Bosch plugs in the car, new eta 8mm wires I modded, and a new fuel filter.

    I want to do the cap, rotar and the o2 sensor.

    WHat else would cause a rough idle? will the cap, rotar and o2 sensor fix the problem? and my valves are noisy ATM, so adjusting them wouldnt hurt either.

    -Steve
    88 Zinno M3

    #2
    Causes of a rough idle include intake leaks, aged plugs, wires, distributor cap/rotor, fuel system or injector issues, mis-adjusted valves, or aged O2 sensor. You've replaced the wires, so they can probably be dropped from the list. Of what is left, intake leaks are the highest probability. A smoke test of the intake will tell where they are.
    The car makes it possible, but the driver makes it happen.
    Jim Levie, Huntsville, AL

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      #3
      Dont forget to check to see if the idle switch on the throttle position sensor is being switched @ idle. Check for continuity @ idle between the left and middle prongs on the TPS

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        #4
        I had the same thing happen to my car my was the idle control I change its running smooth now

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          #5
          Originally posted by Predzy743 View Post
          "... Shakes the whole car at lights and stop signs. Kinda pisses me off so I want to fix it."...
          Just a thought, but have you checked your motor and trans mounts? Perhaps whatever is causing the rough idle is amplified by crapped out mounts, transmitting more vibration to the chassis.
          sigpic
          Parts Wanted
          The Never-ending Resto Mod

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            #6
            I have a similar fault. My car is automatic and when i sit it in gear the vibration goes away. Was thinking it might be the tps. Checking intake tomorrow. Ive replaced: o2 sensor, spark plugs, done a valve set, new fuel pump, new injectors and a reset of the dme. Still not fixed.

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              #7
              To the members in this post that had this problem, how did you resolve it (if you did)?

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                #8
                Originally posted by davem View Post
                To the members in this post that had this problem, how did you resolve it (if you did)?
                Eliminating intake leaks should be the first thing you rule out. After you're 100% sure you don't have any intake leaks, the other stuff is easy to test and fix.
                sigpic

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                  #9
                  Clean all the shit off of your Crank sensor. Not to say this is a cure all but, I was amazed at how something so simple made such a difference.
                  [IMG]http://www.r3vlimited.com/board/

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                    #10
                    Originally posted by lateracer View Post
                    Eliminating intake leaks should be the first thing you rule out. After you're 100% sure you don't have any intake leaks, the other stuff is easy to test and fix.
                    Yeah I took it to a shop & they presumably did some vacuum leak tests but who knows...it was a waste of money. How much labor is a smoke test usually? 1 hour? less?

                    Also, I will take a look at my crank sensor.

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                      #11
                      I'd think it would be no more than one hour of labor.
                      The car makes it possible, but the driver makes it happen.
                      Jim Levie, Huntsville, AL

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