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troubleshooting the m20

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    troubleshooting the m20

    Every time im gonna start the car i have to cranck it a few times before it actually starts and runs.. it does it whenever it wants... i have checked almost everything and dont know what it might be!. I checked for spark, fuel, timing, cpr, tps,afm, ecu.. relays etc, and nothing.. i replaced the engine a few months ago with a rebuilt one(not because of the problems, but due to a turbo project).. and still does the same thing. the engine its a 89 from a 325i.. someone told me that theres a censor on the transmission that its linked somehow to the flywheel, but i replaced the flywheel and clucth along with the new engine and didnt saw any sensor, i also searched on realoem and my tranny doesnt have a sensor... any help or advice on what should i check would be aprecciated guys! thanks and sorry for my english!...
    no more boosted m20, 91 318i...

    #2
    Have you checked your fuel pressure regulator?

    Closing SOON!
    "LAST CHANCE FOR G.A.S." DEAL IS ON NOW

    Luke AT germanaudiospecialties DOT com or text 425-761-6450, or for quickest answers, call me at the shop 360-669-0398

    Thanks for 10 years of fun!

    Comment


      #3
      yea... i did, im sure its nothing related with fuel, i performed several fuel pressure test, fuel delivery rate test, checked injectors etc...
      no more boosted m20, 91 318i...

      Comment


        #4
        The sensor on the flywheel is a crank position sensor, but I'm not sure if 89s had them. You can test it via the instructions in the Bentley manual.

        Comment


          #5
          Only the ETA motor had crank position on the flywheel...that ain't it.

          Closing SOON!
          "LAST CHANCE FOR G.A.S." DEAL IS ON NOW

          Luke AT germanaudiospecialties DOT com or text 425-761-6450, or for quickest answers, call me at the shop 360-669-0398

          Thanks for 10 years of fun!

          Comment


            #6
            ^^^ right.... my cpr its located in the crank pulley
            no more boosted m20, 91 318i...

            Comment


              #7
              If the only problem is hard starting, work through:

              Idle or hard starting problems are most commonly caused by intake leaks and/or
              a sticky or defective Idle Control Valve (ICV). The only reliable method of
              locating intake leaks is to have a smoke test run on the intake and crank case
              and to test the brake booster with a gage and vacuum pump. The complete list
              of possible causes of an intake leak is:

              Intake boot
              Throttle body gasket
              ICV hoses & connections
              Brake booster, hoses, and connections
              Crank case breather hose
              Evaporative control hoses, valve, and expansion tank
              Fuel pressure regulator & hose
              Injector seals
              Valve cover gaskets & bungs
              Oil filler cap
              Dip stick o-rings
              Oil return tube o-rings

              While leaks in some of those can be found by inspection or by spraying carb
              cleaner on suspect areas, not finding leaks that way doesn't eliminate the
              possibility. Only a smoke test will really work.

              Once the possibility of intake leaks is eliminated, the ICV needs to be
              removed and cleaned with carb cleaner until the vane inside moves freely. When
              the ignition is switched on you should be able to feel vibration from the
              ICV. If no vibration the ICV is bad, there's a problem with its wiring or
              connector, there's a problem with the TPS, or the DME (or Idle Control Module
              (ICM) on an ETA car) is faulty.

              For the DME (or ICM) to control idle, the idle switch in the TPS must work
              correctly. The switch should close when the throttle stop is 0.020-0.060" off
              the idle stop screw.

              The fuel system should be tested via the suite of tests in the Bentley manual
              as invalid rail pressure can be a contributor to idle and starting problems. A
              simple injector check is to pull the injectors, jumper the fuel relay to run
              the pump, and see if the injectors are leaking. You can also point the
              injectors into a towel, remove the coil wire, and crank the engine to see if
              all of the injectors appear to be spraying in a similar fashion. The best
              approach to possible injector problems is to have the injectors cleaned and
              flow tested. Since raw fuel can or will be released in these tests, have a
              fire extinguisher handy.

              The O2 sensor can be a contributor to idle problems. The O2 sensor is a
              scheduled maintenance item with a useful life of no more than 100k. If the
              sensor has that mileage or more (or is of unknown age), replace it.

              The AFM can be a contributor. If the vane doesn't move freely or the
              resistance track is worn the DME may be receiving invalid data from the
              AFM. And if someone has fiddled with the bypass air adjustment the DME may be
              unable to stabilize idle. The bypass air adjustment should only be adjusted
              per the procedure in the Bentley and with an exhaust gas analyzer. And even
              then everything else associated with engine management has to first be
              operating properly. If the AFM becomes a suspect, replacement with a good used
              unit is the best approach.

              Improperly adjusted or malfunctioning valves will affect idle and starting. As
              can compression issues from ring or cylinder wear. A valve adjustment is
              called for every 15k. A useful diagnostic is to run compression and leak down
              tests on the engine. And aged ignition wires, plugs, distributor cap, or
              rotor can cause problems. Insulation does break down with time and heat. And
              since the youngest E30 is going on 19 years old, if the ignition system is
              original or the plugs are old replacement is indicated.

              Although not usually a problem, a bad DME temp sensor is a possibility. That
              generally won't cause an unstable idle, but can cause hard cold or hard hot
              starts and/or a rough idle. As can problems with the timing reference sensors.

              When all other possibilities have been eliminated and idle or starting
              problems persist, replacement of the DME, or if applicable the ICM, is
              indicated.
              The car makes it possible, but the driver makes it happen.
              Jim Levie, Huntsville, AL

              Comment


                #8
                ^^^^Hey! thanks again for the help! i decided i was gonna live with the aluminium flywheel ratlle noise lol....

                No intake/ vaccum leaks/ icv checked and cleaned, afm checked and cleaned, fuel system checked, tmp censor replaced (6 months ago), tps adjusted, o2 also replaced a few months ago,cps was replaced as well, i did everything as bentley manual describes it!... ignition parts such as ignition coil, cap rotor, wires and spark plugs brand new along with rebuilt head...all grounds checked, i swap ecu's from two friends wich their e30 had no problems at all..

                Before i replaced the engine it was doing the same thing... so im assuming it might be some kind of electrical problem,
                no more boosted m20, 91 318i...

                Comment


                  #9
                  no more suggestions?
                  no more boosted m20, 91 318i...

                  Comment

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