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Intermittent Idle surge problem on M20 engine

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    Intermittent Idle surge problem on M20 engine

    I have a 1987 325E BMW with M20 engine and 5 speed manual Tranny.
    There has been this intermittent problem with the idle surging
    up and down between 800-1000 rpms. It only does this when there is no load on the engine. If you are sitting at a red light/stop sign then it occurs,
    especially in the morning or when is a little cooler outside. Once you put the car in gear and being moving the problem goes away.
    We have replaced all the vacuum hoses and checked for leaks like a month ago.
    I pulled the ICV off and cleaned it out with brake parts cleaner too.
    Anyone have any ideas what is going on with it?
    My best guess is the idle control valve is going bad.
    Thanks much! :)


    Originally Posted by Blunt
    I've done this so much I have a toenail on my dick.

    #2
    Very typical of an Idle control valve... that is most likely the culprit. good luck
    Joe Funk -- Portland Oregon
    That Guy.
    03 X5. 3 liter obviously.

    Comment


      #3
      Pretty sure 87, 325e's have a cold start valve. Go to realoem.com and put in the last seven digits of your serial number. Go to valves/pipes fuel ingection diagram. It will be the #9 part. 325i's don't have this part. Maybe a cheaper fix than the ICV.

      Comment


        #4
        smack the shit out of your DME and see if it happens anymore


        Comment


          #5
          Parts

          So either http://cgi.ebay.com/ebaymotors/ws/eB...MEWA:IT&ih=012

          or



          ?


          Originally Posted by Blunt
          I've done this so much I have a toenail on my dick.

          Comment


            #6
            but what could possibly go wrong with the ICV module? do those parts really fail?

            i have an 87 325e and the same problem exists... even replaced the ICV, but not the module yet.
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              #7
              Doesnt sound like the cold start valve. I dont think that would cause a surging. It sounds like DME or possible a fuel pressure regulator given all vacuum is sealed and working properly.
              Start the car and unhook your ICV. If the idle surges to a rev.. its working. You can feel the ICV working as it vibrates and what not.

              All my experience has come lately on my E car. Starting to notice all the problems, because its all the same at some point for everyone.

              Comment


                #8
                replace all the little coolant sensors first, and clean out your ICV very well.

                i went through this for a long time.

                and check for tears in any rubber intake/vacuum lines.

                Comment


                  #9
                  coolant sensor

                  One thing I have noticed is that the coolant sensor trouble light is on at the roof panel. Mechanic replaced the coolant temp sensor last summer, but he said there was still something amiss.
                  I know it is not a vacuum leak, and I cleaned out the ICV good with brake parts cleaner. DME sounds plausible...how hard are they to swap out?
                  DME is above the glove box correct?
                  I wish I could figure it out as I am sure it craps the gas mileage out, and car has been running rather poochy the past week.


                  Originally Posted by Blunt
                  I've done this so much I have a toenail on my dick.

                  Comment


                    #10
                    Tps?
                    Originally posted by chileelky
                    amaze about the enthusiasm e30 generate

                    Comment


                      #11
                      Sounds like a vacuum leak honestly. I dunno if you fixed this or not, but i've come a long way with my eta lately. These motors are a science it seems.

                      Take a tube and put it to your ear. Take the other end of the tube and move it around the engine bay. Find your leak. I've purchased new hoses from BMW with razor slits in it before so check all your hoses going to the intake mani and throttle body and check your intake elbow. You'll find it

                      Comment


                        #12
                        I have been told by 2 separate techs who used to work on bmws that this problem is sometimes caused by injector o-rings. I had replaced a lot of things on my eta to eliminate this problem, same with our old 85 528e which had it very bad. this included ICVs, afms, tps, coolant sensors, hoses, lines, dme, and sealing up a bunch of possible leak areas.

                        Never replaced injector o-rings though. Its worth a shot for what they cost.
                        Old and improved:

                        Comment


                          #13
                          Originally posted by EtaSport View Post
                          I have been told by 2 separate techs who used to work on bmws that this problem is sometimes caused by injector o-rings. I had replaced a lot of things on my eta to eliminate this problem, same with our old 85 528e which had it very bad. this included ICVs, afms, tps, coolant sensors, hoses, lines, dme, and sealing up a bunch of possible leak areas.

                          Never replaced injector o-rings though. Its worth a shot for what they cost.
                          where would one get the parts for this? any auto parts store should carry these right?
                          Continuous For Sale Thread
                          323i s50

                          Comment


                            #14
                            Originally posted by rosphill View Post
                            I have a 1987 325E BMW with M20 engine and 5 speed manual Tranny.
                            There has been this intermittent problem with the idle surging
                            up and down between 800-1000 rpms. It only does this when there is no load on the engine. If you are sitting at a red light/stop sign then it occurs,
                            especially in the morning or when is a little cooler outside. Once you put the car in gear and being moving the problem goes away.
                            We have replaced all the vacuum hoses and checked for leaks like a month ago.
                            I pulled the ICV off and cleaned it out with brake parts cleaner too.
                            Anyone have any ideas what is going on with it?
                            My best guess is the idle control valve is going bad.
                            Thanks much! :)
                            I had the same problem, on the same car specifically.
                            then i checked the ICV, and it vibrates good.

                            So, i move on, and try to replaced it with used ICV ( has same vibration compare to the old one )of the same car off the wrecking yard,
                            + my oil cap was chipped off ( the outer lip) and i replaced that at the same time.

                            Voila, it fixed now!

                            So, thats all i did ;)
                            http://www.kingofeurope.net/2010/

                            Comment


                              #15
                              definitely check your throttle position switch.
                              I'd rather have Sarah Palin 1 hearbeat away from the Presidency than Nancy Pelosi 2 heartbeats away.

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