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Surging Idle E30 325e 1986

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    Surging Idle E30 325e 1986

    So this issue was there when i purchased the car. When i would give it gas the acceleration would be hesitant, and would stay around the same rpm's until it leveled out and got better around 3k rpm's. I decided that my issue had something to do with my coil so i replaced it, that obviously didn't help.

    After I replaced the coil, i thought it would be a good idea to unplug any wire i could see and spray electric connection cleaner on all of them (bad idea on my part) . The next day i started the car and it instantly revved to 3k and stayed there for about 1 minute before i shut it down. I proceeded to start the car and shut it off many times, tapping on the ICV, TPS, Air box sensor and had no success in fixing the problem. I believe that when i was tapping on the TPS i may have thrown it off of calibration, because these sensors are supposed to be screwed on a certain way.

    My next course of action, was to pull some stuff apart, I removed the airbox, the throttle (because TPS is connected on the underside), and ICV. I started by cleaning the ICV and shaking it, it is making a clicking noise so i believe it still works (it also vibrates when ignition is on)!? I bought a new TPS and air filter, and installed both. I believe that the TPS was bad because people having the same issue say that this usually fixes it, and when i would pull the throttle (with the car off) i could not hear the microswitch clicking.

    After assembling the new parts, and everything back together, i started the car. It was no longer high idling at 3k rpm's but was now surging, between 1k and 2k constantly, and also the fuel economy gauge was going from 0 to 40 along with the rpm movement. I think i messed something up when i switched the TPS but i am not experienced enough to know what lol. I am hoping maybe someone has had the same issue or knows what my next move should be. I was thinking of getting a smoke test done, to be sure that there are no vacuum leaks going on. Another reason i believe it may be the TPS is that, oil and coolant was getting on everything under the throttle including the tps and the original one was covered in gunk.

    I am very new to the forum and hope someone can help me, i also have a video that i took today showing my gauges as the surging occurs. https://www.youtube.com/watch?v=cyIW...Y&spfreload=10 (video of the car idling weird) https://www.youtube.com/watch?v=d3NncT62mJ0 ( video of the gauges)

    #2
    Something something vacuum leaks, something something smoke test.
    Interested in vintage cars? Ever thought about racing one? Info, photos, videos, and more can be found at www.michaelsvintageracing.com!

    Elva Courier build thread here!

    Comment


      #3
      Originally posted by ELVA164 View Post
      Something something vacuum leaks, something something smoke test.
      Ok I will go to pep boys tomorrow and get this done, i thought it would be a good idea just to see if there are any leaks. But when i took the car for a drive yesterday, when i give it gas it hesitates for a millisecond and starts to accelerate unusually, its almost like it skips to about 10% throttle instead of starting at 1% throttle!?

      Comment


        #4
        :hitler:
        Originally posted by andrewliebner View Post
        Ok I will go to pep boys tomorrow and get this done, i thought it would be a good idea just to see if there are any leaks. But when i took the car for a drive yesterday, when i give it gas it hesitates for a millisecond and starts to accelerate unusually, its almost like it skips to about 10% throttle instead of starting at 1% throttle!?
        Why go to Pep Boys? If you do the old carburetor cleaner/MAF cleaner/brake clean spray trick, you'll find your vacuum leak. Get a can, shoot it at your vacuum lines, your oil return tube, by the fuel rail, at the throttle body, the intake boot and the brake booster. These are common areas for vacuum leaks.

        If the idle jumps while you're spraying a specific area, you found a leak.
        "Leafeon" '92 Lagunengrun 325i Vert (Daily Driver/Project)
        http://www.r3vlimited.com/board/showthread.php?t=366044
        The stickers make it go faster. :nice:

        Comment


          #5
          Originally posted by UlrichFennec View Post
          :hitler:

          Why go to Pep Boys? If you do the old carburetor cleaner/MAF cleaner/brake clean spray trick, you'll find your vacuum leak. Get a can, shoot it at your vacuum lines, your oil return tube, by the fuel rail, at the throttle body, the intake boot and the brake booster. These are common areas for vacuum leaks.

          If the idle jumps while you're spraying a specific area, you found a leak.
          Okay i will try that first, thanks man !

          Comment


            #6
            Originally posted by UlrichFennec View Post
            :hitler:

            Why go to Pep Boys? If you do the old carburetor cleaner/MAF cleaner/brake clean spray trick, you'll find your vacuum leak. Get a can, shoot it at your vacuum lines, your oil return tube, by the fuel rail, at the throttle body, the intake boot and the brake booster. These are common areas for vacuum leaks.

            If the idle jumps while you're spraying a specific area, you found a leak.
            This is not necessarily true. This method will find large leaks, but the system is sensitive enough to be affected by smaller ones which require a smoke test to find.
            Interested in vintage cars? Ever thought about racing one? Info, photos, videos, and more can be found at www.michaelsvintageracing.com!

            Elva Courier build thread here!

            Comment


              #7
              Originally posted by ELVA164 View Post
              This is not necessarily true. This method will find large leaks, but the system is sensitive enough to be affected by smaller ones which require a smoke test to find.
              Thanks for the additional help! A++ I figured this much, as i have been spraying all over the fuckin place with no success :)

              Comment


                #8
                I just had this problem with my 1984 325e. Here's what mine sounded like.

                It turned out to be my TPS. When the car is at idle, it's supposed to use a different fuel map, but if the switch isn't working correctly, it thinks the throttle plate is open. This tells the MPG computer in the cluster that the car is moving and it tries to calculate MPG, but it can't because you're not moving and the gauge tops out. The richer throttle fuel map revs the engine up to 2k until the DME reads "holy crap that's rich" from the oxygen sensor, cuts fuel, and the engine drops back down.

                That's my theory at least. But I'm just a home gamer.

                You should be able to hear the switch clicking. The throttle switch is also very easy to do a continuity test on to make sure the switch is functioning. If the switch is functioning and this problem persists, I would think that it's just not adjusted properly. While you're at it, unhook the ICV and test the resistance across the two pins. I believe the spec is around 10 ohms.

                Also make sure that your throttle cable has just a bit of slack in it. If the switch is improperly adjusted in the right direction and the cable is pulling on the throttle arm, it might cause this.

                Comment


                  #9
                  Originally posted by flumph View Post
                  I just had this problem with my 1984 325e. Here's what mine sounded like.

                  It turned out to be my TPS. When the car is at idle, it's supposed to use a different fuel map, but if the switch isn't working correctly, it thinks the throttle plate is open. This tells the MPG computer in the cluster that the car is moving and it tries to calculate MPG, but it can't because you're not moving and the gauge tops out. The richer throttle fuel map revs the engine up to 2k until the DME reads "holy crap that's rich" from the oxygen sensor, cuts fuel, and the engine drops back down.

                  That's my theory at least. But I'm just a home gamer.

                  You should be able to hear the switch clicking. The throttle switch is also very easy to do a continuity test on to make sure the switch is functioning. If the switch is functioning and this problem persists, I would think that it's just not adjusted properly. While you're at it, unhook the ICV and test the resistance across the two pins. I believe the spec is around 10 ohms.

                  Also make sure that your throttle cable has just a bit of slack in it. If the switch is improperly adjusted in the right direction and the cable is pulling on the throttle arm, it might cause this.
                  The funny thing is that the last thing i fucked with before the car started doing the same thing as yours was the TPS, i have the original, one i got from a 325i at a junkyard, and one from autozone, i think i put mine back on correctly when i reinstalled the throttle body back on. How did you know yours was messed up? and as far as the ICV goes i took it off and cleaned it, but while i was spraying cleaner in some small ball came out, could that have been a vital part? like a ball bearing or float ball?

                  Comment


                    #10
                    So, i fixed my e30, it was the ICV, i must have used carb cleaner to clean it instead of wd-40 and it dried it or the part was faulty. Thanks to everyone who gave advice.

                    Comment

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