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Possible Causes of intermittent Loss of spark

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    Possible Causes of intermittent Loss of spark

    What are the possible causes of intermittent loss of spark on all 6 cylinders?

    Parts
    aftermarket WOLFV500 ECU wasted spark and sequential fuel.
    3 channel ignitor module (Bosch MS) (7 pins , ground + 3 inputs + 3 outputs)
    Bosch OE wasted spark system (common +ve pin for the 3 coils and 3 -ve inputs from ignitor)

    Major Symptoms
    engine stalls and wont restart. problem is intermittent in that will have major issues for a day or two where wont start at all then seem to resolve itself.
    sometimes will start and run for a couple seconds and stall and refuse to restart

    Minor Symptoms
    initially had the odd issue where it would cut out but restart fine.
    on a couple occasions engine misfired for split second but resolve itself in split second

    engine just stalls / cuts out does not splutter like fuel delivery issues

    what works
    everything else seems to work fine e.g.
    - cranks fine,
    - all electrical works
    - fuel injectors work
    - crank sensor appears to work fine (ECU reads cranking rpm) did change out with a working one but no difference
    - logging on the laptop revealed nothing out of ordinary

    Thoughts
    - 3 channel ignitor was replaced (it seemed to initially fix problem for about 6 weeks with zero issues or symptoms) was convinced it solved the problem but issue has returned yesterday.
    - could ignitor be damaged by ECU or something ?
    - cam sensor seems to be ok as fuel delivery works
    - crank sensor seems to be fine swapped out known good one
    - could be bad connection?
    - previous test of coil seemed that had 12V source not test that yet since new issues
    - all 3 coils failing simultaneously is not likely
    - all wires and / or plugs failing at same time seems unlikely
    - could be bad ECU that has the 3 channels all fail at same time intermittently?
    Last edited by digger; 08-14-2019, 09:12 PM.
    89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

    new build thread http://www.r3vlimited.com/board/showthread.php?t=317505


    #2
    Hows your Dwell settings? What are the chances the ignition module is overheating? Doesn't really explain your symptoms completely but might do? does the ignition module get overly hot?

    Can you use different outputs on your ecu to do ignition? although admittedly unlikely that all 3 outputs are playing up. unless something common to all the ign outputs is playing up in the ecu? bad solder joint in the ecu itself?

    dunno if any of this helped.

    Comment


      #3
      My thoughts were that first one failed/ was failing due to heat so i added a heat shield for the module. it has always been located at stock coil location. worked for several years in direct line of sign about 1ft from headers without any shield at all. so its possible the first was faulty due to heat

      i added a heat shield for extractors (a year ago) and a separate shield for the module (when module was replaced) it is also installed on a "heat sink" aluminium plate with the conductive gel. it still gets hot as under bonnet temps are what 70-80C? the shop probably should have installed within cabin?

      dwell settings i dont recall off top of my head. i remember the shop that installed everything initially (4 years ago or whatever) said they reduced the dwell to stop the coils from overheating but i had a few years trouble free with whatever was there
      89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

      new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

      Comment


        #4
        Have you done any logs in the ECU to see what goes on when it does its thing? or looked at the ECU when its playing up to see if any errors thrown?

        Pretty out there idea but i wonder if a sensor is playing up causing it to hit some sort of ignition cut.

        Comment


          #5
          i've logged a no start, nothing unusual. once i did have a trigger SYNC error and NOISE warning but battery was dying after several previous cranks so probably voltage issues as never had the error reappear when battery has been in good charge

          ive also logged where engine stalls while driving. nothing unusual seen

          ive also logged when engine momentary loss of power while idling but not enough to stall (engine dropped to 500 rpm). nothing unusual

          At one point i thought might be cam sensor due to the SYNC error but there is fuel, i dont think the fuel injection would happen without cam sensor signal.

          ive thought maybe bad battery as could do with a replacement but engine cranks fine so cant see it being that. i was going to preemptively replace cam sensor but done want to throw parts without proper tests.


          i should be able to test the signal to ignition module with LED test light?

          89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

          new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

          Comment


            #6
            I would look into the documentation for your ecu and see what the ignition output is. If its a logic level then it will be 0-5V. I think this will show up on an LED test light. An LED test light may have a resistor in it for use on 12V, so it might not show up on 5V (or be very dim).

            It sounds like you have been at this for a while, you could temporarily hard wire LEDs to the ignition outputs to the bosch module, and have three blinking LEDs in your engine bay. Then when the issue occurs you can immedatily see if the LED's are flashing which would tell you if the ECU outputs are working. Depends what you have access too but you could buy a male and female plug for your ignitor and make an inline adaptor so you dont need to hack any of your wiring. you can buy knock off bosch plugs really cheap on ebay. If you did this and it is 5V then you would just need to put a resister in with the LED as most LEDs run on 3V ish. It would probably be ok without resistor, but you may just run the LEDs a bit hot.




            Comment


              #7
              the ECU tech support just replied and said a LED test light will work to see signal to Igniter and reverse polarity with test light to test whats coming out igniter. obviously check common 12V at coil and ground at igniter first working back towards ECU
              89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

              new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

              Comment


                #8
                Which Bosch ignition module? This one? Test signal in and out of the ignition module, the symptoms match an ignition module that is overheating or on its way out. Seeing if it has signal in and out during the no-start condition would confirm eliminate it with certainty. If it is near the exhaust, being mounted on an AL block may not be enough, I believe the internal transistors have thermal protection and will cut out if temps get too high which is a good possibility given the heat of the exhaust area. The sheet metal and thus the heat sink the module is bolted to is also typically hot around the exhaust side and may be working against you. Typical OE installation of these coil drivers, as seen in turbo Volvos and other vehicles that use them, is on the side of the engine bay opposite of the exhaust. I don't know what Wolf ECU circuitry looks like but it's unlikely to be failing or overheating ignition transistors in the ECU, the ignition module input current is rated at 10-20mA which is well within the spec of any ignition output on any ECU I've heard of.
                Last edited by varg; 08-16-2019, 12:13 PM.
                @turbovarg
                '91 318is, M20B25, T3/T04E 60 trim (15psi), megasquirt, coilovers, Z3 rack, cold AC
                [b u i l d]
                [Car of the month: April 2018]

                0c8b7c9527af628a346878feb14bf757

                Comment


                  #9
                  yes that's it i also found a motec doc attached that shows wiring properly. i didnt test signals previously because i didnt have that datasheet with pins identified and i thought i needed a scope which i dont have. im going to test it and if its the ignitor (my thoughts are heat damage) as a possblity and if so i will get a new one and relocate to cold side of engine. might be good idea regardless of it being the issue

                  coil 9220061800
                  https://www.nzefi.com/product/bosch-...inder-engines/
                  Attached Files
                  Last edited by digger; 08-16-2019, 04:07 PM.
                  89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

                  new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

                  Comment


                    #10
                    Does the Wolf ECU software have an test mode you can use? That would be the best bet, triggering each output manually and keeping it on longer than it would be with a cranking test so that you can see signal on a test light or meter easily. At cranking dwell I think you should be able to see a LED flash, but it has been a long time since I tested an ignitor in a car so I don't remember how well that works.
                    @turbovarg
                    '91 318is, M20B25, T3/T04E 60 trim (15psi), megasquirt, coilovers, Z3 rack, cold AC
                    [b u i l d]
                    [Car of the month: April 2018]

                    0c8b7c9527af628a346878feb14bf757

                    Comment


                      #11
                      Originally posted by varg View Post
                      Does the Wolf ECU software have an test mode you can use?
                      not that i'm aware of.
                      89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

                      new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

                      Comment


                        #12
                        You swapped the crank sensor. Have you tried swapping the harmonic balancer?
                        AWD > RWD

                        Comment


                          #13
                          No I don't see it as being the issue as I get a crank rpm signal when there's no spark and when I log it cutting out it correctly shows rpm dropping down in time ( it doesn't drop out instantaneously )
                          89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

                          new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

                          Comment


                            #14
                            so as the car was at my mechanic getting road worthiness done he had not had a chance to do anything until today as he was away.

                            he had charged the battery as it was only 12.2V when he chekced which is odd after having driven it for 1 hr or so should have good charge.

                            So today it started fine and could not replicate the issue. he said that the alternator might not be charging the battery sometimes. when i got home the voltage with engine running (idling) was 13.5V with aux fan and lights on, but when i put cabin fan on hi and turn a few other things on the voltage dropped to 12.5V. so it seems the alternator is probably sketchy. last time i checked it was 13.8V or so a while back

                            it may have nothing to do with the issue but sounds like a replacment is needed. its probably the original so he said might as well replace whole thing rather than voltage regulator only.

                            what say eveyone? and where do you get a good reco unit qulaity brand OE or bosch etc
                            89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

                            new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

                            Comment


                              #15
                              had multiple cut out occurences that were able to be restarted immediatelty. Fortunately one cut out occurence would not restart for 5min just cranked continuously no spark on any cylinders.

                              so test light suggests the coil is faulty as with and without the issue the test light behavious was the same.

                              89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

                              new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

                              Comment

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