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Power problems with 1985 (C Reg) 520i

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  • graham_e28
    Hi, I m hoping some of you may have some suggestions. My 1985 (C reg) 520i will no longer go above 2500 rpm in any gear or when revved stationary - above this
    Message 1 of 6 , Dec 14, 2005
      Hi, I'm hoping some of you may have some suggestions. My 1985 (C reg)
      520i will no longer go above 2500 rpm in any gear or when revved
      stationary - above this it 'stutters' and all loses power. I have had
      a diagnostic done on the ECU but am told all is well. It has been
      suggested that one of the sensors has failed and the ECU has
      automatically entered mid range figures for its output and gone into
      'LOS' mode to prevent the engine from being damaged - however, I
      cannot find anything about this in any of the manuals available to me.
      The ECU is the early L-Jetronic and I'm also told that the number of
      sensors is limited and anyway, the diagnostics do not extend to the
      sensors as with later models.

      Any suggestions welcome from those more experienced with these
      wonderful but frustrating beats,I posted before on 23 Nov 05 (message
      4015) but no responses ( probably you're all as confused as I am )
      .... it's getting awfully embarrassing only being able to do 65mph on
      the motorway and having zilch acceleration. Even push-bikes beat me
      away from traffic lights!

      Thanks in advance
      Graham
    • dave ruiz
      Have you done a fuel pressure test? -Dave Ruiz If you plant poison ivy, you won t harvest strawberries. - William Stephens When I die, I want to die like my
      Message 2 of 6 , Dec 15, 2005
        Have you done a fuel pressure test? -Dave Ruiz



        If you plant poison ivy, you won't harvest strawberries. - William Stephens
        When I die, I want to die like my grandfather-- who died peacefully in
        his sleep.
        Not screaming like all the passengers in his car."
        --Author Unknown





        >From: "graham_e28" <graham_e28@...>
        >Reply-To: bmwe28@...
        >To: bmwe28@...
        >Subject: [bmw e28] Power problems with 1985 (C Reg) 520i
        >Date: Wed, 14 Dec 2005 22:12:38 -0000
        >
        >Hi, I'm hoping some of you may have some suggestions. My 1985 (C reg)
        >520i will no longer go above 2500 rpm in any gear or when revved
        >stationary - above this it 'stutters' and all loses power. I have had
        >a diagnostic done on the ECU but am told all is well. It has been
        >suggested that one of the sensors has failed and the ECU has
        >automatically entered mid range figures for its output and gone into
        >'LOS' mode to prevent the engine from being damaged - however, I
        >cannot find anything about this in any of the manuals available to me.
        >The ECU is the early L-Jetronic and I'm also told that the number of
        >sensors is limited and anyway, the diagnostics do not extend to the
        >sensors as with later models.
        >
        >Any suggestions welcome from those more experienced with these
        >wonderful but frustrating beats,I posted before on 23 Nov 05 (message
        >4015) but no responses ( probably you're all as confused as I am )
        >.... it's getting awfully embarrassing only being able to do 65mph on
        >the motorway and having zilch acceleration. Even push-bikes beat me
        >away from traffic lights!
        >
        >Thanks in advance
        >Graham
        >
        >
        >
        >

        _________________________________________________________________
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        http://search.msn.click-url.com/go/onm00200636ave/direct/01/
      • george mogos
        Hi there By the sound of it - refusing to accelerate past a certain engine speed and stuttering under acceleration - it makes me think of the ignition timing
        Message 3 of 6 , Dec 17, 2005
          Hi there

          By the sound of it - refusing to accelerate past a certain engine speed and stuttering under acceleration - it makes me think of the ignition timing setting. Ignition timing is not fixed for the whole engine speed range, it is regulated by a centrifugal actuator in the distributor and by a pressure gauge in the intake - that is to monitor both the engine speed and the throttle position. The higher the engine speed the more ignition timing will be "forwarded" in order to make the most of the explosion pressure at TDC. If the ignition timing is well ahead of the prescribed 20-ish degrees (check your Bentley or Haynes manual for your engine) and adding to that the dynamic advance that the engine itself generates, there will be a certain threshold at which the ignition will happen well ahead TDC, so gigantic forces will actually "brake" the piston - and consequantly the whole engine. If the engine has a mechanical distributor, just "back it off", by loosening the screw underneath it
          with the engine idling and turning it gently in the clockwise direction (mark the position of the distributor before this in case you want to retrieve it later). The engine speed should decrease when you do this. I can't recommend how much you should turn it, but if you do it in steps of a few degrees each you will get to test the effects by driving the car after each adjustment. Of course, you MUST tighten the screw after you adjust the timing, otherwise frictional forces will drive the distributor astray. If this DIY method will make you laugh (and I have to say it takes years of experience to actually do it properly just by listening to the engine), any garage will do it for you for a small fee by using a special flash tool. I hope this helps you out, but if I wasted your time I hope I may be pardoned.
          Cheers, George

          dave ruiz <daveruiz50@...> wrote:
          Have you done a fuel pressure test? -Dave Ruiz



          If you plant poison ivy, you won't harvest strawberries. - William Stephens
          When I die, I want to die like my grandfather-- who died peacefully in
          his sleep.
          Not screaming like all the passengers in his car."
          --Author Unknown





          >From: "graham_e28"
          >Reply-To: bmwe28@...
          >To: bmwe28@...
          >Subject: [bmw e28] Power problems with 1985 (C Reg) 520i
          >Date: Wed, 14 Dec 2005 22:12:38 -0000
          >
          >Hi, I'm hoping some of you may have some suggestions. My 1985 (C reg)
          >520i will no longer go above 2500 rpm in any gear or when revved
          >stationary - above this it 'stutters' and all loses power. I have had
          >a diagnostic done on the ECU but am told all is well. It has been
          >suggested that one of the sensors has failed and the ECU has
          >automatically entered mid range figures for its output and gone into
          >'LOS' mode to prevent the engine from being damaged - however, I
          >cannot find anything about this in any of the manuals available to me.
          >The ECU is the early L-Jetronic and I'm also told that the number of
          >sensors is limited and anyway, the diagnostics do not extend to the
          >sensors as with later models.
          >
          >Any suggestions welcome from those more experienced with these
          >wonderful but frustrating beats,I posted before on 23 Nov 05 (message
          >4015) but no responses ( probably you're all as confused as I am )
          >.... it's getting awfully embarrassing only being able to do 65mph on
          >the motorway and having zilch acceleration. Even push-bikes beat me
          >away from traffic lights!
          >
          >Thanks in advance
          >Graham
          >
          >
          >
          >

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        • goldsoul2003
          I ve got exactly the same problem as you. 1985 c reg 520i n i can t get over 70mph. Just suddenly happened whilst driving. Feels like i m only running on 3
          Message 4 of 6 , Jan 14, 2006
            I've got exactly the same problem as you. 1985 "c" reg 520i n i can't
            get over 70mph. Just suddenly happened whilst driving. Feels like i'm
            only running on 3 cylinders instead of 6 even tho it idles fine at
            running temperature.

            I've done a vacuum check on the inlet manifold & I have found that I
            have got very little vacuum working through the inlet manifold
            itself. So the cars working with normal fuel levels but with very
            little air. Therefore using a very rich mixture & flooding the
            engine. Sounds like I have a split air pipe somewhere around the
            throttle housing.

            I'll let you know what my fault was when its sorted.

            > >To: bmwe28@...
            > >Subject: [bmw e28] Power problems with 1985 (C Reg) 520i
            > >Date: Wed, 14 Dec 2005 22:12:38 -0000
            > >
            > >Hi, I'm hoping some of you may have some suggestions. My 1985 (C
            reg)
            > >520i will no longer go above 2500 rpm in any gear or when revved
            > >stationary - above this it 'stutters' and all loses power. I have
            had
            > >a diagnostic done on the ECU but am told all is well. It has been
            > >suggested that one of the sensors has failed and the ECU has
            > >automatically entered mid range figures for its output and gone
            into
            > >'LOS' mode to prevent the engine from being damaged - however, I
            > >cannot find anything about this in any of the manuals available to
            me.
            > >The ECU is the early L-Jetronic and I'm also told that the number
            of
            > >sensors is limited and anyway, the diagnostics do not extend to the
            > >sensors as with later models.
            > >
            > >Any suggestions welcome from those more experienced with these
            > >wonderful but frustrating beats,I posted before on 23 Nov 05
            (message
            > >4015) but no responses ( probably you're all as confused as I am )
            > >.... it's getting awfully embarrassing only being able to do 65mph
            on
            > >the motorway and having zilch acceleration. Even push-bikes beat me
            > >away from traffic lights!
            > >
            > >Thanks in advance
            > >Graham
            > >
            > >
            > >
            > >
            >
            > _________________________________________________________________
            > Don't just search. Find. Check out the new MSN Search!
            > http://search.msn.click-url.com/go/onm00200636ave/direct/01/
            >
          • Guy DiCesare
            Hi everyone. My 88 535is temp gauge behaves very strangely (totally erratic). All systems check out OK but this really makes me nervous. Someone suggested that
            Message 5 of 6 , Jan 14, 2006
              Hi everyone. My 88 535is temp gauge behaves very
              strangely (totally erratic). All systems check out OK
              but this really makes me nervous. Someone suggested
              that there is a nut on the back side of the gauge that
              comes loose and does this. Has anyone else ever fixed
              this problem by locating and tightening a single nut?
              Thank for your input. GUY PS: all other gauges are
              fine G

              --- goldsoul2003 <no_reply@...> wrote:

              > I've got exactly the same problem as you. 1985 "c"
              > reg 520i n i can't
              > get over 70mph. Just suddenly happened whilst
              > driving. Feels like i'm
              > only running on 3 cylinders instead of 6 even tho it
              > idles fine at
              > running temperature.
              >
              > I've done a vacuum check on the inlet manifold & I
              > have found that I
              > have got very little vacuum working through the
              > inlet manifold
              > itself. So the cars working with normal fuel levels
              > but with very
              > little air. Therefore using a very rich mixture &
              > flooding the
              > engine. Sounds like I have a split air pipe
              > somewhere around the
              > throttle housing.
              >
              > I'll let you know what my fault was when its sorted.
              >
              > > >To: bmwe28@...
              > > >Subject: [bmw e28] Power problems with 1985 (C
              > Reg) 520i
              > > >Date: Wed, 14 Dec 2005 22:12:38 -0000
              > > >
              > > >Hi, I'm hoping some of you may have some
              > suggestions. My 1985 (C
              > reg)
              > > >520i will no longer go above 2500 rpm in any gear
              > or when revved
              > > >stationary - above this it 'stutters' and all
              > loses power. I have
              > had
              > > >a diagnostic done on the ECU but am told all is
              > well. It has been
              > > >suggested that one of the sensors has failed and
              > the ECU has
              > > >automatically entered mid range figures for its
              > output and gone
              > into
              > > >'LOS' mode to prevent the engine from being
              > damaged - however, I
              > > >cannot find anything about this in any of the
              > manuals available to
              > me.
              > > >The ECU is the early L-Jetronic and I'm also told
              > that the number
              > of
              > > >sensors is limited and anyway, the diagnostics do
              > not extend to the
              > > >sensors as with later models.
              > > >
              > > >Any suggestions welcome from those more
              > experienced with these
              > > >wonderful but frustrating beats,I posted before
              > on 23 Nov 05
              > (message
              > > >4015) but no responses ( probably you're all as
              > confused as I am )
              > > >.... it's getting awfully embarrassing only being
              > able to do 65mph
              > on
              > > >the motorway and having zilch acceleration. Even
              > push-bikes beat me
              > > >away from traffic lights!
              > > >
              > > >Thanks in advance
              > > >Graham
              > > >
              > > >
              > > >
              > > >
              > >
              > >
              >
              _________________________________________________________________
              > > Don't just search. Find. Check out the new MSN
              > Search!
              > >
              >
              http://search.msn.click-url.com/go/onm00200636ave/direct/01/
              > >
              >
              >
              >
              >
              >
              >


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            • goldsoul2003
              Ok my cars working properly again. The vacuum advance on the distributor had siezed but also the pulse transmitter inside the distributor (that the vacuum
              Message 6 of 6 , Jan 31, 2006
                Ok my cars working properly again.

                The vacuum advance on the distributor had siezed but also the pulse
                transmitter inside the distributor (that the vacuum advance connects
                onto) had also siezed! I fitted new ones & sucked on the small pipe &
                you could see the pulse transmitter rotating & then spring back in2
                place when the vacuum stopped (as it should). The car was then
                running really lumpy. I then realised that there was a missing earth
                cable from the side of the distributor (theres a male spade terminal
                on the distributor body facing the air filter). So i hooked up a wire
                and earthed it under the diagnostic connector on the main engine
                earth point n hey presto! I got my power back! All I need to do now
                is adjust the timing slightly & she'll be back 2 normal.



                --- In bmwe28@..., goldsoul2003 <no_reply@y...> wrote:
                >
                > I've got exactly the same problem as you. 1985 "c" reg 520i n i
                can't
                > get over 70mph. Just suddenly happened whilst driving. Feels like
                i'm
                > only running on 3 cylinders instead of 6 even tho it idles fine at
                > running temperature.
                >
                > I've done a vacuum check on the inlet manifold & I have found that
                I
                > have got very little vacuum working through the inlet manifold
                > itself. So the cars working with normal fuel levels but with very
                > little air. Therefore using a very rich mixture & flooding the
                > engine. Sounds like I have a split air pipe somewhere around the
                > throttle housing.
                >
                > I'll let you know what my fault was when its sorted.
                >
                > > >To: bmwe28@...
                > > >Subject: [bmw e28] Power problems with 1985 (C Reg) 520i
                > > >Date: Wed, 14 Dec 2005 22:12:38 -0000
                > > >
                > > >Hi, I'm hoping some of you may have some suggestions. My 1985 (C
                > reg)
                > > >520i will no longer go above 2500 rpm in any gear or when revved
                > > >stationary - above this it 'stutters' and all loses power. I
                have
                > had
                > > >a diagnostic done on the ECU but am told all is well. It has been
                > > >suggested that one of the sensors has failed and the ECU has
                > > >automatically entered mid range figures for its output and gone
                > into
                > > >'LOS' mode to prevent the engine from being damaged - however, I
                > > >cannot find anything about this in any of the manuals available
                to
                > me.
                > > >The ECU is the early L-Jetronic and I'm also told that the
                number
                > of
                > > >sensors is limited and anyway, the diagnostics do not extend to
                the
                > > >sensors as with later models.
                > > >
                > > >Any suggestions welcome from those more experienced with these
                > > >wonderful but frustrating beats,I posted before on 23 Nov 05
                > (message
                > > >4015) but no responses ( probably you're all as confused as I
                am )
                > > >.... it's getting awfully embarrassing only being able to do
                65mph
                > on
                > > >the motorway and having zilch acceleration. Even push-bikes beat
                me
                > > >away from traffic lights!
                > > >
                > > >Thanks in advance
                > > >Graham
                > > >
                > > >
                > > >
                > > >
                > >
                > > _________________________________________________________________
                > > Don't just search. Find. Check out the new MSN Search!
                > > http://search.msn.click-url.com/go/onm00200636ave/direct/01/
                > >
                >
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