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  • Sportster electronic ignition

    Hello,

    I'm slowly learning about my "new to me" Sportster and I'm wondering if anyone else has a "Lumenition in association with GEMS" electronic ignition setup on a BMW 6 cylinder running triple Weber carbs? The distributor seems to be one of those fixed units running off the front of the cam, and there is a small heat sink Lumenition unit next to the coil, and a larger blue module in the passenger footwell, labelled as a Competition Engine Management System, Type C410, Serial No 01168, made in 1996. The unit has a D-type multi-pin connector on its lower surface, with 9 pins. I suspect the blue unit can be connected to a laptop in some way to allow adjustments, but no details came with the car, and I can't find any details on-line, having spent a couple of hours Googling. The car was built by Marlin themselves in 1997, so I suspect this was their way of overcoming the engine management system issues associated with ditching injection and moving to triple Webers. I've emailed Lumenition and GEMS, but thought it also worth trying on here as well in case they no longer provide support. I suspect the timing may be a bit too advanced at the moment - there is popping back through the carbs, a biggish flat spot under acceleration, a high idle and I suspect I can sometimes here pinking under load. The engine is a BMW M30 unit, I suspect from a 635 based off the engine number.
    I've hopefully managed to paste an image of the blue module below.
    Capture.JPG

    That aside, I took my Dad for a run yesterday afternoon and its still an epic ride, even if its not quite spot on yet. We went up to Bentham from Burnley, which gave us view of the Lake District fells, Morecambe Bay and Ingleborough before we headed home.
    Capture2.JPG
    Original builder of SWB Cabrio chassis no. 04-33 reg. no. CRN540Y - had a 2.8L Cologne V6 when I sold it in 2011
    Briefly owned Marlin Berlinetta Q670XBB for about 4 months in 2012
    Did own SWB Marian 1800TC Roadster Q741LPP - modified for trials by Fourtune Engineering
    Now own Marlin Sportster with 3.5L BMW straight six powerplant P764DOD - proof that absolute power corrupts absolutely!

  • #2
    Re: Sportster electronic ignition

    A bit of an update.

    GEMS replied that they'd never heard of the unit, but when I rang Lumenition I spoke to someone who seemed very familiar with this particular installation. He reckoned that a great deal of effort went into setting up the system, which also incorporates a throttle position sensor and a crank angle sensor, and it was very unlikely the timing would move unless a component was deteriorating. Lumenition no longer make this, or anything like it, but they can provide software support, but it runs on 1990's verisons of Windows.

    Now I am a mechanical engineer by training and education, and I'm always ready to blame electrics and electronics first, but I decided in this case it was also worth checking fuelling. I am an absoulte beginner on Weber DCOE's, and to be honest have always felt a bit daunted by their complexity, so I bought Des Hamill's book on Weber and Dellorto sidedraft carbs. After spending an hour on Wednesday trying to adjust idle mixture, it was apparent I probably had idle jets that were way too weak. So I pulled all 6 and found I had two different sizes, but both were well on the weak size in terms of recommendations for jet versus cylinder capacity. Further on-line checking tended to confirm that. I then pulled the main jets, air correctors and accelerator pump jets. and found all tended to be well on the weak side of recommendation.

    My car was sold to me as a 3.3litre engine, but checking actual engine numbers makes me suspect its a 3.5litre unit, possibly from a shark nose 635csi. I couldn't find much in the way of jetting recommendations for a 635 engine on triple Webers, but I could find a complete list of jets etc. for a 3.4litre Jaguar straight six - close enough in capacity for a first attempt. So at 22:00 on Wednesday I ordered £80 (including next day delivery) worth of bits on-line from Webcon - jets for idles, mains, accelerator pumps and air correctors. I want to use the car on a drive to Tan Hill Inn tomorrow, but thanks to Webcon's excellent service everything arrived ready for me to fit when I got home from work today. After a quick test drive, the car seems transformed. There is only very slight, very occasional spitting back, and the acceleration flat spot seems to have been greatly reduced if not disappeared completely - I need some open roads to confirm. I haven't had time to bottom idle mixture adjustment or individual carb airflow's yet, but its miles better to drive than it was before today, with all six idle mixture screws just set to 1 1/2 turns from closed.

    I'll report back a bit more after tomorrow's run. I have also ordered a Bentley Publications manual on the BMW E28 5 series , which has the same engine as I suspect I've got, so I will be checking the timing when it arrives, but at the moment I think my original diagnosis of the timing being out was probably wrong.
    Original builder of SWB Cabrio chassis no. 04-33 reg. no. CRN540Y - had a 2.8L Cologne V6 when I sold it in 2011
    Briefly owned Marlin Berlinetta Q670XBB for about 4 months in 2012
    Did own SWB Marian 1800TC Roadster Q741LPP - modified for trials by Fourtune Engineering
    Now own Marlin Sportster with 3.5L BMW straight six powerplant P764DOD - proof that absolute power corrupts absolutely!

    Comment


    • #3
      Re: Sportster electronic ignition

      Its really interesting to read the whys and where fores of others. thanks for the story so far.

      Comment


      • #4
        Re: Sportster electronic ignition

        Re the spitting back on acceleration I would try a richer accelerator pump jet. As the rest were on the weak side I would suspect this is too. Worth a try anyway and a quick cheap fix. Pete.

        Comment


        • #5
          Re: Sportster electronic ignition

          So this is overdue a bit of an update.

          Prior to the run in September I changed jets for idles, mains, accelerator pumps and air correctors. The car seemed to run much better with less spitting back, but still some cracks and bangs from the exhaust. The run was a great day out, albeit with a bit of a pot luck route due to a bad accident between two motorbikes on the road from Ribblehead to Hawes.

          I've used the car for runs to work once or twice between then and now, and still quite a lot of backfires, and an occasional cutting out at traffic lights, which I put down to lack of use.

          The weather forecast for today was reasonable and I had a holiday to use up, so I rang my Dad and suggested we make the run up to Tan Hill by the route we didn't manage in September. Unfortunatley we hit a hailstorm on the A59 after Pendle Hill and reached the conclusion I really need to fit a set of windscreen wipers, which for some reason has never been done. Creeping home at 30 mph with the windscreen tilted flat the backfire seemed to become a misfire and the cutting out got worse.

          Back in the garage a quick check of the exhaust headers seemed to indicate at least one cylinder not giving its best, and upon pulling the spark plug it was very wet. Holding the plug against the head revealed no spark, but the adjacent cylinder had a spark, albeit quite weak. Swapping plugs to leads seemed to indicate the lead was the issue and checking resistance has convinced me I need 6 new leads, plus a coil to dizzie lead. Eurocarparts seem to want a small fortune for a set, and the coil to dizzie lead is a special, so Mr Retro Leads is going to make me up a set. I will report back when fitted. The plugs themselves look like they just need regapping and a bit of a clean.
          Original builder of SWB Cabrio chassis no. 04-33 reg. no. CRN540Y - had a 2.8L Cologne V6 when I sold it in 2011
          Briefly owned Marlin Berlinetta Q670XBB for about 4 months in 2012
          Did own SWB Marian 1800TC Roadster Q741LPP - modified for trials by Fourtune Engineering
          Now own Marlin Sportster with 3.5L BMW straight six powerplant P764DOD - proof that absolute power corrupts absolutely!

          Comment


          • #6
            Re: Sportster electronic ignition

            Another update.

            New leads fitted (two of the originals were knackered according to my multimeter so maybe its been down on cylinders for a while), and bought a new coil but spark issues continue. I could force a spark out of the coil to the cam cover with the ignition switched on and a piece of wire, but nothing doing at the plugs when i pressed the starter button, including when a plug was connected direct to the coil to distributor lead (thus ruling out the distributor I thinK).

            So I have removed the blue Lumenition box and associated "power module" that was wired feeding the coil and sent them to Lumenition who will do a diagnosis/error check and tell me if there is anything wrong and whether they can be repaired if there is. They can't supply new units but will diagnose/repair if they can and the fee for the check is £50, so worth spending I think. Hope to have them back before Xmas in case I manage to steal some time in the garage. If the blue box is knackered i may be forced to go coil free and install something like a Megajolt or Nodiz or Emerald - I'd rather not get that deep into engine management at the moment so fingers crossed its repairable.
            Last edited by acbluemarlin; 11-12-19, 07:54 PM. Reason: Omitted some info
            Original builder of SWB Cabrio chassis no. 04-33 reg. no. CRN540Y - had a 2.8L Cologne V6 when I sold it in 2011
            Briefly owned Marlin Berlinetta Q670XBB for about 4 months in 2012
            Did own SWB Marian 1800TC Roadster Q741LPP - modified for trials by Fourtune Engineering
            Now own Marlin Sportster with 3.5L BMW straight six powerplant P764DOD - proof that absolute power corrupts absolutely!

            Comment


            • #7
              Re: Sportster electronic ignition

              Hi
              I know this is going to sound daft but have you checked the earth strap. Many an ignition issue has been cured by fitting a big fat earth lead directly from the engine to the battery negative. Easily overlooked when retro fitting / refitting an engine.
              Jon
              Mk2 SWB Marina Roadster with a 1800 Fiat Twin Cam engine and 5 speed Abarth gearbox built in 1987
              - I have no idea what I am talking about........ but my advice is always free! -

              Comment

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