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Help!! Car running rich/misfire/starting problem. It's a mystery

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    #1

    Help!! Car running rich/misfire/starting problem. It's a mystery

    UPDATE: pulled the plug wires while it was running and it didnt do anything in 4 cylinders but all the plug wires have spark. spark at the wrong time?

    Well...my car took a shit on me. I've owned it for a few months now and once every 2 weeks or so the car would randomly start running rich and misfiring and wanted to die. Then out of no where it would run great again. It would happen hot or cold. It was hard to diagnose because it would fix itself. Well just a couple days ago I went to start it and it was acting up like usual so I drove it around hoping it would fix itself....it didn't. Now it rarely starts and when it does it runs stupid rich,misses and sputters when you give it gas, doesn't want to idle. When I was driving it it would sputter when I give it gas then once engine rpms got higher(3k) it would pull hard then loose power toward the top end.

    Things I've done:
    Pulled the plugs and they were all black so I cleaned them up
    Check fuel pressure(its good)
    Checked injectors(working correctly)
    New dizzy cap
    New spark plug wires
    Different afm
    New fuel pressure regulator
    Newer tps
    Known good ecu
    Timing is spot on
    Newer 02 sensor
    All engine grounds are solid
    No vacuum leaks

    This car straight pissing me off I can't figure it out its a mystery problem that can't be solved. But I thought I would post this to see if anyone has ever had these symptoms.it seems to me it's not getting enough spark but when I pull the plugs while its running its getting spark.

    I appreciate all the help I can get.
    Last edited by Znick742; 03-10-2013, 01:20 PM.
    Current car-86 325e never ending project

    You only get out as much as you put into it
    Tags: None
    #2
    How did you confirm no vac leaks? Have a smoke test done?

    Check the ohm reading on the water temp sensor. Could be an issue as well.
    -Build http://www.r3vlimited.com/board/showthread.php?t=295277

    Comment

      #3
      Originally posted by FLG View Post
      How did you confirm no vac leaks? Have a smoke test done?

      Check the ohm reading on the water temp sensor. Could be an issue as well.
      Yeah. Changed most hoses too just for good measure. Forgot to mention the car is a 86 325e. The temp sensor would make it run that bad? To where it won't start? Ill ohm it in the morning to see.
      Current car-86 325e never ending project

      You only get out as much as you put into it

      Comment

        #4
        Yes, it is possible. If the sensor is telling the ecu the engine is hot when its actually cold it wont be giving enough fuel...and vise versa. You could try unplugging it first and trying to start it and see what happens.
        -Build http://www.r3vlimited.com/board/showthread.php?t=295277

        Comment

          #5
          Originally posted by FLG View Post
          Yes, it is possible. If the sensor is telling the ecu the engine is hot when its actually cold it wont be giving enough fuel...and vise versa. You could try unplugging it first and trying to start it and see what happens.
          Yeah I unplugged it, it didn't change anything
          Current car-86 325e never ending project

          You only get out as much as you put into it

          Comment

            #6
            Did you confirm you are getting good solid spark? Also what was your fuel pressure?
            -Build http://www.r3vlimited.com/board/showthread.php?t=295277

            Comment

              #7
              Originally posted by FLG View Post
              Did you confirm you are getting good solid spark? Also what was your fuel pressure?
              Yeah I pulled the plug wires off the spark seemed strong, I'm not sure how else to check it. It was 34psi
              Current car-86 325e never ending project

              You only get out as much as you put into it

              Comment

                #8
                Originally posted by FLG View Post
                Did you confirm you are getting good solid spark? Also what was your fuel pressure?
                I was thinking maybe the coil isn't giving out enough spark causing it to run really rich
                Current car-86 325e never ending project

                You only get out as much as you put into it

                Comment

                  #9
                  Sounds good.

                  Id perform a smoke test, generally bad/no idle issues are caused by vac leaks. Also could be a faulty icv (remove it, clean with carb cleaner...should hum/vibrate when key in in ON position)

                  Also did you make sure tps is adjusted correctly? Switch should close when the throttle is stop is 0.020-0.060" off the idle stop screw.

                  Could also be a faulty ICM

                  An intake leak will cause the DME to run a richer mixture...id honestly start there. Check intake boot for cracks and double check hoses. You could try disconnecting the AFM, possible an engine with an intake leak with the AFM disconnected will cause it to run better/run.
                  -Build http://www.r3vlimited.com/board/showthread.php?t=295277

                  Comment

                    #10
                    Check the cold start valve. It could be leaking or stuck on.
                    The car makes it possible, but the driver makes it happen.
                    Jim Levie, Huntsville, AL

                    Comment

                      #11
                      Originally posted by FLG View Post
                      Sounds good.

                      Id perform a smoke test, generally bad/no idle issues are caused by vac leaks. Also could be a faulty icv (remove it, clean with carb cleaner...should hum/vibrate when key in in ON position)

                      Also did you make sure tps is adjusted correctly? Switch should close when the throttle is stop is 0.020-0.060" off the idle stop screw.

                      Could also be a faulty ICM

                      An intake leak will cause the DME to run a richer mixture...id honestly start there. Check intake boot for cracks and double check hoses. You could try disconnecting the AFM, possible an engine with an intake leak with the AFM disconnected will cause it to run better/run.
                      Yeah tps is right I adjusted it multiple times

                      Ill check for vacuum leaks again today and try unplugging the afm.
                      Current car-86 325e never ending project

                      You only get out as much as you put into it

                      Comment

                        #12
                        Originally posted by jlevie View Post
                        Check the cold start valve. It could be leaking or stuck on.
                        Cold start valve was eliminated after all this started and it continued to do It
                        Current car-86 325e never ending project

                        You only get out as much as you put into it

                        Comment

                          #13
                          Originally posted by Znick742 View Post
                          Cold start valve was eliminated after all this started and it continued to do It
                          Okay... There are two possibilities here. One is that the misfires and starting problem are the result of excessive fuel delivery and the other is that the apparent rich condition and starting problems is the result of misfires. If the rail fuel pressure is correct and a noid light shows normal injector firing, the latter case becomes the more likely case.

                          A smoke test would be the first thing on my list of diagnostics.
                          The car makes it possible, but the driver makes it happen.
                          Jim Levie, Huntsville, AL

                          Comment

                            #14
                            Originally posted by jlevie View Post
                            Okay... There are two possibilities here. One is that the misfires and starting problem are the result of excessive fuel delivery and the other is that the apparent rich condition and starting problems is the result of misfires. If the rail fuel pressure is correct and a noid light shows normal injector firing, the latter case becomes the more likely case.

                            A smoke test would be the first thing on my list of diagnostics.
                            Yeah the first thing I did was rule out vacuum leaks, there's no leaks at all. Then I checked fuel and it was good. I even pulled the injectors out of the head and cranked it to see the stream the injectors were spraying. All injectors were spraying the same and a consistent stream. I put another fpr on it and it did the same thing. I unplugged the afm and it would start then die right away
                            Current car-86 325e never ending project

                            You only get out as much as you put into it

                            Comment

                              #15
                              I unplugged the afm and it would start then die right away
                              That is practically a diagnostic for intake leaks. Have a shop run a smoke test to find them.
                              The car makes it possible, but the driver makes it happen.
                              Jim Levie, Huntsville, AL

                              Comment

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