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Problem with engine dying

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  • #61
    At least one member of this board has reported problems with a brand new Bosch coolant temp sensor. I would still check it, even if it's new.

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    • #62
      This afternoon I replaced the two pin coolant sensor, and tried wiggling the plug for the DME. I will find out if it was the sensor in the morning, and wiggling the plug while the engine was running did nothing. Not a bit of a change.

      Lets see what happens in the morning...

      Will
      '69 Datsun 2000 Roadster vintage race car (Street driven on a regular basis :taz
      '59 Alfa Romeo 101 Sprint (HUGE project :uhoh
      '88 M3

      Comment


      • RAD2LTR
        RAD2LTR commented
        Editing a comment
        It didn't cut out this morning, but it was also nearly 70 degrees out when I left for work, so I'm not going to say I found the issue.

        Will

    • #63
      So.... I installed my DME back in the car this morning, fired right up. Let it warm up a bit while I put my tools away, and then set out to do a test drive. I got to the end of my driveway and it cut out and didn't want to start. Opened the glove box and wiggled the DME plug around and it started right up. I wiggled it some more and got it to cut and die. Restarted it, pulled back up the driveway and promptly removed my DME. Reinstalled the loaner one and no issues. Clearly my DME has something wrong with it. I checked all the pins and they were all tight, nothing moved. THey are all perfectly straight as well. It appears I had two issues going, one was a failing temp sensor, the other was the DME itself. Oddly though, when I first swapped the DME it was cutting and dying. As soon as I replaced that sensor, the cutting was gone. I put 90 miles on it yesterday without so much as a hiccup. While I had the harness apart I checked all the plugs and nothing was lose there. Also, with the other DME installed, I wiggled the plug around and had no change. There must be a lose solder joint in my original DME or something.

      One thing I have noticed is that with the loaner DME that has a Conforti chip, it takes a lot longer for the engine to light off. Probably 25 revolutions. (My DME with the IIGO chip takes about 5 before it lights off.) Is this common with the Conforti chip?

      I have a remanufactured DME on order from Programa. Should be here by the end of the week.

      Will
      '69 Datsun 2000 Roadster vintage race car (Street driven on a regular basis :taz
      '59 Alfa Romeo 101 Sprint (HUGE project :uhoh
      '88 M3

      Comment


      • #64
        Originally posted by RAD2LTR View Post
        So.... I installed my DME back in the car this morning, fired right up. Let it warm up a bit while I put my tools away, and then set out to do a test drive. I got to the end of my driveway and it cut out and didn't want to start. Opened the glove box and wiggled the DME plug around and it started right up. I wiggled it some more and got it to cut and die. Restarted it, pulled back up the driveway and promptly removed my DME. Reinstalled the loaner one and no issues. Clearly my DME has something wrong with it. I checked all the pins and they were all tight, nothing moved. THey are all perfectly straight as well. It appears I had two issues going, one was a failing temp sensor, the other was the DME itself. Oddly though, when I first swapped the DME it was cutting and dying. As soon as I replaced that sensor, the cutting was gone. I put 90 miles on it yesterday without so much as a hiccup. While I had the harness apart I checked all the plugs and nothing was lose there. Also, with the other DME installed, I wiggled the plug around and had no change. There must be a lose solder joint in my original DME or something.

        One thing I have noticed is that with the loaner DME that has a Conforti chip, it takes a lot longer for the engine to light off. Probably 25 revolutions. (My DME with the IIGO chip takes about 5 before it lights off.) Is this common with the Conforti chip?

        I have a remanufactured DME on order from Programa. Should be here by the end of the week.

        Will
        Damn I'm good lol

        Its not the DME its the connector side. The female receptor on Pin #1 has lessened up a bit so it loses contact with the male pin on the DME. take a jewelers screw driver or a small pick and bend the tabs a little so it makes a tighter contact with he male pin. Problem solved.

        T

        Comment


        • RAD2LTR
          RAD2LTR commented
          Editing a comment
          It doesn't do it at all with the other DME. I shook it, flexed it, and nothing. Not a single hiccup. If it were the female side, I'd think it would still do it. (Although it did it when I first put it in, but hasn't done it since I replaced that temp sensor.)

          When I get the new DME I'll go through and bend the tabs on all the pins so they seat tightly ( It can't hurt, unless I manage to break one.) but I think its actually something inside the DME.

          Will

      • #65
        Well, the gremlin is back, with the borrowed DME. It cut and died last night as I was driving along, freshly paved road, constant speed. Restarted instantly. So, I pulled it out, double checked all the female pins, flexed them down so they are almost touching both sides, checked to see if any move (none did) and tried my DME. It started right up, so I ran back inside to close the back door to the house, and was going to take it for a spin. It died in the garage. Was not interested in running at all on that DME. I rechecked and flexed the female plug pins even tighter, put the loaner one in, and went for a drive. After getting fuel seemed fine, till I was about 2 miles from home. It cut cold again, twice. Restarted like nothing had happened both times. What I find interesting is that it seems to need the key turned off then the ignition re energized for it to run. Before it would hiccup and keep going. Now its a cold cut dead, and a restart is needed.

        This thing is really pissing me off, to the point where I'm tempted to sell it and call it a day. I really hate computer controlled engines. Seriously, give me carbs and a points type distributor over this BS any day of the week.

        Will
        '69 Datsun 2000 Roadster vintage race car (Street driven on a regular basis :taz
        '59 Alfa Romeo 101 Sprint (HUGE project :uhoh
        '88 M3

        Comment


        • #66
          Apologies if you've tried it or people have suggested this.......... What about the wiring in the engine compartment? All these wires have had many years of heat, water, cold thrown at them. Could it be the shaking of the engine when you try and restart may bridge the corroded cable if its hanging on for dear life. Thinking of the coil, coolant temperature ones and the bunch under the inlet manifold? Just a thought................

          Comment


          • #67
            Could the issue be the ignition switch itself? Its pretty clear that my DME has an issue, (Since it has gotten progressively worse to the point that it won't even idle in the garage for 5 minutes.) but I think I have another issue here as well since its still doing the cut with the known good DME. All the wires under the hood look to be in good shape. I've replaced all the sensors, I seriously don't have any other ideas other than somehow finding a NOS wiring harness and redoing the whole bloody thing (its got to be NOS since the odds of the issue being present in another is there.) Honestly, I'm sick of screwing with this thing. Its dangerously close to being banished to a barn and left there. Chasing ghosts is not worth my time.

            Will
            '69 Datsun 2000 Roadster vintage race car (Street driven on a regular basis :taz
            '59 Alfa Romeo 101 Sprint (HUGE project :uhoh
            '88 M3

            Comment


            • #68
              Hi Will,
              Can you borrow a fuel pressure gauge and connect it up to see what the fuel pressure is doing when it dies, on the up shot now it is happening all the time it will be much easier to diagnose.
              If the ignition switch was faulty the RPM needle would drop quickly, not sure if that is happening in you case.
              There is a OBC relay under the dash drivers side which supplies or cuts power to the DME when the code is installed, just wondering if it could be related to your problem.
              Dave

              E30 M3 1987
              Mini Clubman GT
              BMW E36 323 Msport
              Toyota Corona
              KTM 200EXC
              Honda CB50 (1979)

              Comment


              • #69
                Originally posted by Dave @nz View Post
                Hi Will,
                Can you borrow a fuel pressure gauge and connect it up to see what the fuel pressure is doing when it dies, on the up shot now it is happening all the time it will be much easier to diagnose.
                If the ignition switch was faulty the RPM needle would drop quickly, not sure if that is happening in you case.
                There is a OBC relay under the dash drivers side which supplies or cuts power to the DME when the code is installed, just wondering if it could be related to your problem.
                Dave
                How exactly do I check the fuel pressure when it dies, since I never know when it will die? ( I guess I could put my DME back in and stand there and watch, hoping it decides to die. I don't know if that would be a valid test since I know there is an issue with that DME that is different from what is going on with the loaner one.) I have a fuel pressure tester that I could hook in and watch, but I don't know if that would tell me much since it might not do its thing at idle, and if it does, did it die because of the known bad DME, or to the issue that causes the cut with the known good DME (The loaner is a rebuilt one from Programa with a Conforti chip in it.)

                The tach needle falls with engine rpm when the engine cuts (Goes to zero with the clutch in if I'm driving, comes back up if I let the clutch out.)

                I've considered the OBC relay, however I was told by Bill Arnold that if the relay has issues it won't restart. Its totally dead. This was one of my first thoughts, but it sounds like the odds of this being the culprit are pretty low.

                Could it possibly be an issue with the alternator doing something strange? My dad had a Jaguar XJR that would randomly cut out and the issue turned out to be the alternator. (I'm guessing the odds of this being the issue are very low.)

                Will
                '69 Datsun 2000 Roadster vintage race car (Street driven on a regular basis :taz
                '59 Alfa Romeo 101 Sprint (HUGE project :uhoh
                '88 M3

                Comment


                • #70
                  I didn't read through this whole thread carefully, but have you replaced the main relay (behind the coolant tank)? My car started dying on a road trip this past summer and I was able to trace the issue to the main relay.

                  Comment


                  • #71
                    Originally posted by rewilfert View Post
                    I didn't read through this whole thread carefully, but have you replaced the main relay (behind the coolant tank)? My car started dying on a road trip this past summer and I was able to trace the issue to the main relay.
                    That was one of the first things I replaced. Then the pulse generators, fuel pumps, ECU, spark plugs, wires, cap & rotor, coil, water temp sensor, cleaned every ground on the car,

                    Will
                    '69 Datsun 2000 Roadster vintage race car (Street driven on a regular basis :taz
                    '59 Alfa Romeo 101 Sprint (HUGE project :uhoh
                    '88 M3

                    Comment


                    • #72
                      So I threw my spare AFM in because it was there and I'm grasping for anything at this point. Wasn't the AFM. It cut on me twice about 5 min into a drive. I didn't bother pulling over, just clutch in turned it off and restarted. Started instantly. The second time it cut and died, I just turned it from run to off back to run and the engine restarted the second the key made it back to the run position. Could it be a bad ignition switch?

                      Will
                      '69 Datsun 2000 Roadster vintage race car (Street driven on a regular basis :taz
                      '59 Alfa Romeo 101 Sprint (HUGE project :uhoh
                      '88 M3

                      Comment


                      • #73
                        To me that sounds like a relay de-energising causing the EFI to kill the car, and once you cycle the key the relay gets a fresh voltage and starts.

                        As this is starting to happen regularly that is a good thing. Easier to diagnose.

                        To check if the ignition switch is failing and dropping out spark via the coil, run a 12v feed to the coil straight from the battery main feed. Drive the car and if no more cut outs then trace the 12v from coil to ig switch find the fault.

                        If it keeps happening then maybe DME relay, wiring, fuel pump relay or wiring

                        Bridge each relay one at a time to see what stops the cutting out

                        Comment


                        • #74
                          Originally posted by basketcase View Post
                          To me that sounds like a relay de-energising causing the EFI to kill the car, and once you cycle the key the relay gets a fresh voltage and starts.

                          As this is starting to happen regularly that is a good thing. Easier to diagnose.

                          To check if the ignition switch is failing and dropping out spark via the coil, run a 12v feed to the coil straight from the battery main feed. Drive the car and if no more cut outs then trace the 12v from coil to ig switch find the fault.

                          If it keeps happening then maybe DME relay, wiring, fuel pump relay or wiring

                          Bridge each relay one at a time to see what stops the cutting out
                          The relays have all be replaced, so I'm pretty sure its not a relay. That said, it could be a relay being de-energized and re-energized when I turn it off and back on. This would point to the ignition switch wouldn't it?

                          If I run a wire directly from the main power block behind the coolant tank down to the coil, that would leave the coil hot all the time wouldn't it? How would I turn the engine off with a hot coil short of standing on the brakes and letting the clutch out?

                          Will
                          '69 Datsun 2000 Roadster vintage race car (Street driven on a regular basis :taz
                          '59 Alfa Romeo 101 Sprint (HUGE project :uhoh
                          '88 M3

                          Comment


                          • #75
                            Yes as the relays all have been replaced it might be a wiring issue. Each relay has a control side and a load side. If the wiring on the control side gets a high resistance, it could de-energise the relay. I'm not saying its the ignition switch yet. I think as you are getting this fault regularly now, it is time to isolate the circuit causing the problem. Then narrow down the fault in that circuit whether it is a wiring or component issue.

                            Yes the coil will be hot at all times. This is only for testing purposes, so just disconnect the wire once you are satisfied the feed to the coil is either at fault or not. After driving the car just pop the hood and disconnect.

                            If that does not make a difference, then try bridging the load side of the relays one at a time, pins 30 and 87. That takes the control side of the relay out of the equation (86 and 85) . If the fault stops by doing this to one of the relays you can then diagnose that circuit.

                            These are all temporary measures for diagnosis obviously. The cars battery will drain pretty quickly if left on, and risk of burning out a component.

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