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  • #91
    I drove it about 50 miles yesterday and it was fine. Just as it should be. I'm going to give it a week . I have to admit, I'm skeptical that I'd end up with two ECUs that had the same issue, but stranger things have happened.

    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

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    • #92
      I have been watching this thread and I had my car which would start running then die on me. My friend came over to help trouble shoot. It ended up being the ground for the alternator. The bolt and nut came off that attaches to the dip stick. Replaced it and started right up and stayed running. I would have never imagined that would cause the problems I was having.
      Dan

      88 M3
      Black on Black

      San Diego, CA
      USA

      Comment


      • #93
        Originally posted by 99M3Riverside View Post
        I have been watching this thread and I had my car which would start running then die on me. My friend came over to help trouble shoot. It ended up being the ground for the alternator. The bolt and nut came off that attaches to the dip stick. Replaced it and started right up and stayed running. I would have never imagined that would cause the problems I was having.
        I've had that issue as well. The telltale there is the dash lights never go off, aside from the alternator light that never goes on. Eventually the battery goes dead (not charging because no ground to close the circuit.)

        The car still appears to be happy. It was cold this morning, but it started right up, drove to work without an issue.

        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


        • #94
          So, I've managed to drive the car all week without it dying, but it hasn't been quite right. I did a check of the idle CO setting and found that with the TPS plugged in, it ran full rich (zero V), with the pTPS plug bridged, it would go full lean (13V). I thought I might have a vacuum leak (or something) so I pulled the intake off, pulled the IVC off and had a look. It was clean on the inside, so I tested it with 12 v to the center pin, and grounded the other two. One side grounded and the valve moved, the other side did nothing. This leads me to believe I have a zombie ICV. Does this sound plausable? There are no burned resistors in the ECU, and it idles fine.

          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


          • #95
            Originally posted by RAD2LTR View Post
            So, I've managed to drive the car all week without it dying, but it hasn't been quite right. I did a check of the idle CO setting and found that with the TPS plugged in, it ran full rich (zero V), with the pTPS plug bridged, it would go full lean (13V). I thought I might have a vacuum leak (or something) so I pulled the intake off, pulled the IVC off and had a look. It was clean on the inside, so I tested it with 12 v to the center pin, and grounded the other two. One side grounded and the valve moved, the other side did nothing. This leads me to believe I have a zombie ICV. Does this sound plausable? There are no burned resistors in the ECU, and it idles fine.

            Will
            Your TPS switch and ICV are responding as normal for what you have tested. I am not in the testing diagnosis business but understand how these work because I did the research to set up the Haltech Elite properly.
            TPS on the Idle switch closed causes the Idle fuel map to be in effect that is only good for idle. WOT switch causes the WOT fuel map to be in effect. When in between the two, the normal air load map is in effect and takes input for the map cell from the AFM. I do not use this switch but use a rheostat type TPS.
            The ICV is a push pull rotary motor. 12V powers it and the other pins are grounded in PWM to modulate the valve position. The valve wont work properly when simply grounding them by hand. I use the valve with the Haltech.

            Comment


            • #96
              Originally posted by JimK View Post

              Your TPS switch and ICV are responding as normal for what you have tested. I am not in the testing diagnosis business but understand how these work because I did the research to set up the Haltech Elite properly.
              TPS on the Idle switch closed causes the Idle fuel map to be in effect that is only good for idle. WOT switch causes the WOT fuel map to be in effect. When in between the two, the normal air load map is in effect and takes input for the map cell from the AFM. I do not use this switch but use a rheostat type TPS.
              The ICV is a push pull rotary motor. 12V powers it and the other pins are grounded in PWM to modulate the valve position. The valve wont work properly when simply grounding them by hand. I use the valve with the Haltech.
              Its my understanding that if one applies 12V to the center pin on the ICV, then grounds either of the two other pins, the valve will either close, or open. In this case, it opens, but doesn't close. I also verified this on the car, The valve will open, but not close. It also doesn't open all the way, only part way, but won't close at all.

              In setting the idle/CO, I used this method

              1)Check to make sure the throttle switch (TPS) closes just as the throttle butterfly's close (the closer this switch is set, the better the engine will transition between idle and non-idle throttle positions).

              2) Connect the voltmeter between pin 5 (DME oxygen sensor signal on 15 & 20 pin Diagnostic Connector) and ground (pin 19 on a 20 pin or pin 1 on 15 pin) Diagnostic Connector.

              3) Start the engine, while the engine is warming up observes the voltage reading at pin 5 on the Diagnostic Connector.

              4) Once the engine is warm the oxygen sensor signal should read between 5-7 volts average (6 volts +/- 3 volt spec.). If you don't have an averaging volt meter, your volt meter will cycle every second or so between 0 volts and 12 volts the cycling should be 50% duty cycle. The cycling is demonstrating that your fuel injection system is running closed loop. If the oxygen sensor signal is not cycling then you will need to diagnose and repair the DME open loop problem. The problem could be something as simple as the CO adjustment on the Air Flow Meter. (NOTE: If you are too rich, the meter will sit at zero volts (it will also do this if the meter’s battery is dead!). Too lean, it will sit at 12V. As your mixture approaches stoichiometric, the needle will start to cycle, but will stay longer at either 12V or 0V depending on whether you are on the rich or lean side of stoich – TNK).

              5) Shut-off the engine and install the Throttle Switch Bridge on the cable connector for the throttle switch. The Throttle Switch Bridge allows the idle circuit in the DME to operate in open loop mode and sets the idle control valve a nominal position.

              6) Start the engine, check to see that the oxygen sensor signal is reading 5-7 volts (after reset the recording function) or that the voltage is cycling at a 50% duty with a standard volt meter. (the engine will not rev or operate normally with the Throttle Switch Bridge installed)

              7) Adjust the Idle speed screw to 850 rpm's (large brass slot screw recessed in the middle of the 3-4 throttle body) using the record/ averaging function will help accurately set the idle speed as it fluctuates. The minimum and maximum record measurements on the Fluke will help you understand the open-loop idle smoothness. (NOTE – Loosening the screw increases idle speed – TNK)

              8) Shut-off engine, remove the Throttle Switch Bridge and re-connect the throttle switch.

              The reading taken from pins 5 and 19 was either full rich, or full lean, but it wouldn't dither between the two at all. I know it used to because I've done this check/test before every smog check to make sure everything is working correctly. Now, it doesn't. with it bridged, it was pegged lean, and wouldn't shift from full lean. unbridged it was full rich, and no amount of futzing with it would change it. Before I pulled the ICV, I installed my extra afm and ran it without the airbox at idle. I put my hand over the opening, and waited to see if it would enrichen with less airflow, the reading didn't change. It was just stuck at 13V, until the engine died. This lead me to think there was a vacuum leak somewhere so off came the air box and I checked all the hoses, found nothing off, so I looked at the ICV.

              It also looks like the ICVs are NLA both from BMW and Bosch.

              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


              • #97
                Okay, have some more info here. After nearly 4 hrs of ripping (off and on) down highway 1 to Big Sur, the car started to cut and die (eventually completely dying and not wanting to restart) When it died, the fuel pump was running (gotta love a Bosch 044 pump being loud) but as the engine died I could hear the voltage drop at the pump.) Prior to this, off throttle the engine was popping through the exhaust indicating a rich condition. It only started popping a little just before it started cutting. This would suggest a rich condition, likely due to a sudden lean condition. After I pulled over on the side of the road and tried to restart the engine, it would cough and sputter like the AFM was removed, and if I tried to rev the engine it would instantly die. It did this for a good 15 minutes then restarted like nothing had happened. I drove another 5 or so miles and it died again. Same thing. Didn't want to run well, and would eventually die. Finally, it restarted and acted like nothing happened. Based on this it would seem like there is an air valve that opens causing the lean condition. The only thing I can think of is the Evaporative charcoal canister valve randomly opening. This would explain the sudden popping through the exhaust a little before the engine dies. Upon getting home this afternoon (the car was totally fine for the 4 hr trip home) I thought I'd try an experiment by pulling the Evap purge control relay. At idle the moment I pulled the relay it bucked and hacked and sputtered until it died. It acted much like the engine was yesterday . The engine also won't restart with the relay pulled. Its my understanding that one can pull that relay and remove the whole evap assembly without causing any issues, but with my car, this is not the case.

                I know the evap relays are NLA, can I just pull the plug on the valve and call it good? That would effectively keep the valve closed wouldn't it?

                Thanks,
                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


                • #98
                  If the idle control valve opens and doesn't close, the engine would idle at 2000rpm +. It works with a 100hz grounding with varying duty from the dme, not a constant ground from the dme.
                  I wouldn't put up with all the flack from the oem system and dump it for a modern ecu.

                  Comment


                  • RAD2LTR
                    RAD2LTR commented
                    Editing a comment
                    Its not the idle control valve, I think its the charcoal canister valve that is randomly opening when it shouldn't. I'm going to look for a plug to the valve and unplug it to see if that solves anything this afternoon.

                    Will

                    Dumping the OEM ECU would be cool, but I neither have the $, skill, or the time to rewire the whole car as well as program a new ECU.

                  • ColinM
                    ColinM commented
                    Editing a comment
                    An ICV that is stuck in the fully closed position can also prevent the car from starting. (At least on a 325e such was the case.)

                • #99
                  A little update: The car has been great since the weekend before Thanksgiving (It did its cut and die thing at the southern end of Big Sur. It didn't want to stay running, but after I let it sit for a bit it was fine. The fuel pump was running, so an ignition issue) and hasn't missed a beat until this past weekend when I parked to go recycle its old motor oil. I drove across town and it was great, parked and turned it off. Came back out and it would just crank and crank, but not start. (Of course it was dark and I couldn't see anything) I bought some starting fluid and tried it, sure enough it started and ran for a bit, but quit. No fuel. I tried it again and it started like nothing had happened and has been fine, until this morning. I got in to go to work and no start. It cranks fine, but no fuel. After I got home from work this afternoon I got it to run briefly on starting fluid again, but the fuel pump was not running. I checked and swapped the fuses, as well as the relays, and still no go. I highly doubt its a suddenly bad fuel pump between last night when I parked it and this morning when I got in to go to work. Its also likely not either of the new pulse generators for the flywheel. I also tried wiggling the harness at the DME connector while cranking, no go either.

                  Its my understanding that the DME doesn't trigger the fuel pumps until after it sees a signal from the crank sensors. It then goes through the relay and out to the fuel pumps. The wiring and connectors for both pumps are in good shape and tight so I'm pretty sure its not a lose connection. Because it ran for a short period of time, I'd have to guess the dowles in the flywheel are also fine. Swapped relays, no change, so that leaves me with what? Another bad DME? (I don't have any more that work to swap in to check.) Anything else I can check before I pull the DME and send both in to be fixed?

                  Thanks
                  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 appears I have had some shitty luck with new parts this past year. There is power to both fuel pumps, the lift pump runs, and the main pump doesn't run. Reach under with a screwdriver and smack it a few times and it kicks on and runs. I thought 044 pumps were some of the best, most bombproof fuel pumps $ can buy? I checked the connections and both are good, a full 12V cranking.

                    Will

                • I feel your pain. Take a step back and think about it: when it runs, it runs fine. So your ICV, your fuel pumps (once you've replaced the external 044...), relays, DME, distributor, spark plugs, injectors, AFM etc. etc. are working fine there and then. Then suddenly as if struck by lightning the engine dies... You wrote that in the past it would stumble and catch and keep running. However, things got worse and when it died on you, you had to turn the ignition off and restart the car. Sometimes it would start, sometimes not.

                  This behaviour points to the DME suddenly no longer receiving the TDC and/or rpm signal. As soon as the DME doesnt receive either of those signals it no longer fires the coil and switches off the fuel pump too and so the engine dies.
                  In the past the interruption of TDC and/or rpm signals lasted shortly enough that the DME received rpm and tdc signal again before the crank rpm was below the 'minimum cranking speed'. The DME sees this as a start condition hence the DME starting the engine and you experiencing the 'catch and keep running'.
                  The problem worsened over time and the interruption of the rpm and/or TDC signal path into the DME lastet long enough for the crank speed to be below the minimum cranking speed, so the DME didn't fire the coil and injectors like in the past and the engine stopped running. To get it running again you have to cycle the ignition from on to off to on and further to engine start.

                  So what to do?
                  1. You can either fabricate a temporary wiring loom with the proper connectors (TE Connectivity/AMPI junior timer 3 terminal female) connect them to the TDC sensor (thereby disconnecting it from the engine wiring loom) and feed the separate leads to the appropriate terminals INSIDE the DME. Easiest to solder them directly onto the legs that go from connector to circuit board. That way you circumvent the engine loom and the DME connector. Do this for TDC signal first (as bad rpm signal shows in the tach needle twitching if it lasts long enough and you haven't reported noticing that) as chances are greater the problem lies there.
                  If the engine no longer dies, then it's either a bad connection within the DME connector or the appropriate wires in the engine loom.
                  If it still dies repeat the above for the RPM sensor and reconntect the TDC sensor to the engine wiring loom

                  OR
                  2. you can hook up a scope to the appropiate terminals inside the DME and log the signal for TDC and rpm. If either or both signals drop out suddenly the DME doesnt receive the signal(s) and stops firing the coil and switches of the fuel pump. The possible causes as listed above apply.

                  Comment


                  • I put 230 miles on the car with some spirited driving it was fine, until I was down to about 1/2 a tank of fuel. Then the fuel pump got really loud and the idle degraded. Again, I replaced BOTH pumps. It drove fine, but seemed like it was running lean as it was a little fluttery when I put my foot down.

                    I think the cutting issue is all DME, and I managed to find two that had the same issue. I haven't had any issues of that sort with the third one.

                    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


                    • You're not gonna do anything I suggested, are you?

                      Good luck chasing your tail and keep ignoring the fact that whilst you can throw all the parts at it you like the wiring loom remains the same 30 year old loom nonetheless...

                      Comment


                      • Originally posted by hardtailer View Post
                        You're not gonna do anything I suggested, are you?

                        Good luck chasing your tail and keep ignoring the fact that whilst you can throw all the parts at it you like the wiring loom remains the same 30 year old loom nonetheless...
                        Well seeing as how I don't have time to make a new wiring harness, nor do I have a scope, its kinda hard to do anything else. I do plan on sending my other DME off to be fixed. I have just had other financial obligations lately. Just because the wiring loom is only 30 years old doesn't mean there is an issue with it. My other two cars are 50 and 60 years old and they both have the original harnesses in them. The one that drives has never had any electrical issues, and the other one hasn't driven since the early 70s, but seems to be okay ( dropped a battery in it before I started pulling it apart and things appeared to work. )

                        Honestly I'd love to shitcan the whole EFI system and just run carbs, but I can't if I want to pass smog.
                        '69 Datsun 2000 Roadster vintage race car (Street driven on a regular basis :taz
                        '59 Alfa Romeo 101 Sprint (HUGE project :uhoh
                        '88 M3

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