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  • Abrupt Engine Cutoff

    Any pointers as to what to look at/for would be greatly appreciated.

    I have an 89 M3(Original Rebuilt S14) motor has been running great up until a few days ago. The problem doesn't seem to be consistent but it is annoying to say the least.

    What would happen is that during a short stint on the road it would just cut off and die. No sputtering, no signs that it wanted to die it just shut off. It started right back up and I was able to drive it home which was about another 20 miles.

    The next day it started up just fine and everything is running really strong. Stretched her legs out on the highway and then BAM shut off again but this time it would just crank but not start. Thought maybe gas but that was not the case. It finally cranked and got it back home again.

    So today the car would start and would not produce the problem again. Thought it could have been the DME but that was ruled out with another DME I borrowed. Checked the wires and all seem to be in place.

    I am thinking perhaps the Coil? I did mess with it to get a new boot on it but decided that I would buy a new COIL so I left it alone. I have since tightened it.

    Someone else mentioned the relay that controls the DME under the steering column? Apparently when the car died out like that it reset the OBC back to KM. Would that be like a cut off for the fuel/car?

    It doesn't seem like loose wires or burnt wiring. Could the Coil do this? Would it reset the OBC? So far the car is running fine and the issue hasn't happened again. But I need to know what is causing it. Do not want to be stranded.

    Any assistance is greatly appreciated.

  • #2
    I chased a similar issue years ago on my datsun. It was the coil. The next time it dies, check and see if your coil is hot to the touch. It shouldn't be. Warm is ok, hot is not. Since it will restart after sitting for a while, I would put my $ on the coil.

    Lets see if anyone else chimes in. It might be something else. How is the charge on the battery? I had an issue last week where my ground wire on the alternator worked its way out and I was driving on just the battery. I noticed that my idiot lights quit lighting up one morning, didn't think too much about it since I had other dash cluster issues going on (dead speedo) The day it died, it was really slow to start on my way to work, and then when I left to go home, it was very very slow starting. It died 3 miles later. When it died, it reset the OBC. I got another battery, dropped it in, drove home and fixed the alternator issue. My money is still on the coil however.

    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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    • #3
      RAD2LTR - I hoping it is the Coil as well. The charge on the battery is really strong. But I will also have that tested as well and the alternator. When the car run she runs strong but being stranded is never something I want to worry about even though it can happen on any car. Thank you.

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      • #4
        Does the car have an aftermarket alarm with immobilizer fitted?

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        • #5
          I had the same problem with mine and it turned out to be my ECU.
          I pulled my ecu and tested it on another members s14 and his car started just fine with my ECU plugged in.
          So I prematurely dismissed it.
          So I replaced all the flywheel sensors, plugs, plug wires, rotor & cap, coil and the car would still stall randomly...
          Saw a killer deal on eBay for an ECU for $100! and bought it because having a spare for $100 was a no brainer =).
          Plugged her in to test it and my car never stalled again...
          I had a friend of mine test the board and he told me there maybe some circuits on the board that would come apart at certain temps causing the ECU to stop working.

          Hope this helps and Good luck

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          • #6
            Originally posted by xworks View Post
            Does the car have an aftermarket alarm with immobilizer fitted?
            No aftermarket immobilizer

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            • #7
              Originally posted by ///Mavrikno13764 View Post
              I had the same problem with mine and it turned out to be my ECU.
              I pulled my ecu and tested it on another members s14 and his car started just fine with my ECU plugged in.
              So I prematurely dismissed it.
              So I replaced all the flywheel sensors, plugs, plug wires, rotor & cap, coil and the car would still stall randomly...
              Saw a killer deal on eBay for an ECU for $100! and bought it because having a spare for $100 was a no brainer =).
              Plugged her in to test it and my car never stalled again...
              I had a friend of mine test the board and he told me there maybe some circuits on the board that would come apart at certain temps causing the ECU to stop working.

              Hope this helps and Good luck
              Going to replace Coil just because its time. Will look into another ECU per your experience as well. If anyone has a good ECU for sale please PM me.

              Would the Conforti chip cause an issue? Its runs without a hiccup outside of the immediate shutdown. Haven't been able to reproduce today.

              I am left thinking Coil or ECU.

              Thanks for the suggestions and responses.

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              • #8
                it's an electrical issue for sure and one that's depending on something getting warm and losing contact ( PCB inside the DME or its relais )
                how did you rule out the dme? did it happen with through known good one?

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                • #9
                  Well the COIL was not it. Did find some corrosion on the middle pin of the fuel injection connector. It's the middle connector with three prongs under the injector rail.

                  It seems to be dumping fuel at times. When it dies it just dies. After a little while the car starts but dies under load but hums along at idle.

                  Another strange incident occurred was with key in ignition when the motor died the injectors were firing still. You can hear them go off - clicking. If so that would push fuel into the system right?

                  It will drive great for a hit the it starts up again and will continue to so so until you let it rest for an hour and then it runs fine for a little while.

                  Could corrosion on the connector create this intermittent problem? I will clean it out but trying to figure out if the ECU is the real culprit. At $400 for an ECU I would hate to experiment. I read that if I remove the ECU I can't check the soldering points on it since there were problems with design/solder points in the pad ?

                  Sorry intermittent problems drive me insane. Had a BMW mechanic look at it but it doesn't happen at the times I need it to happen to get a true diagnosis.

                  Thanks again for any suggestions. As I mentioned before anyone with a good ECU have a good price on them or should I look at the solder points?

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                  • #10
                    Try the Main Relay.
                    Had an identical problem years ago,,, otherwise perfectly running car would just randomly shut off.
                    3 dealer mechanics couldn't figure it out,,, I found a bad main relay...
                    jimmy p.
                    87 E30 M3 Prodrive British Touring Car
                    88 E30 M3 Zinnoberot - Street
                    88 E30 M3 Lachsilber - Race (#98 SCCA SPU)
                    92 E30 M Technic Cabrio - S14 POWERED!
                    98 318Ti M44, Base - Morea Green
                    04 Ford F350 - V10

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                    • #11
                      Originally posted by jimmy p. View Post
                      3 dealer mechanics couldn't figure it out,,, I found a bad main relay...
                      That was also a common problem with older e12, e21 and e24s. It was a "combo relay" back then and it made life of many a living hell ;-) Including myself. ;-)

                      And slightly different scenario can also happen. The engine sputters and will only keep idle. Play with the gaz pedal and the engine would want to die. It would happen sporadically. In my case it was traced to a bad AFM.

                      Lee


                      [email protected]

                      1969 2002 racecar
                      1989 M3 racecar
                      e39 Touring

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                      • #12
                        Thanks guys. I will try to check the main relay. Is that main relay E30 specific or S14 specific? The AFM will be next. Yeah I can see how it could drive someone BATTY!!! Run then don't run then run again and then decides to sputter and then idle perfectly then dies. UGH!!
                        Last edited by ALINE_M5; 02-14-2013, 05:20 AM.

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                        • #13
                          I believe the Main Relay is same across all E30s.
                          Its just a simple Bosch relay, nothing proprietary or peculiar.
                          I think its a 4 pin,,, going by memory (but my memory is shot...)
                          jimmy p.
                          87 E30 M3 Prodrive British Touring Car
                          88 E30 M3 Zinnoberot - Street
                          88 E30 M3 Lachsilber - Race (#98 SCCA SPU)
                          92 E30 M Technic Cabrio - S14 POWERED!
                          98 318Ti M44, Base - Morea Green
                          04 Ford F350 - V10

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                          • #14
                            Okay just ordered the Main Relay(4 Prong) and the Fuel Injection "Diode" Relay (5 Prong). I hope that it is not the Ignition Control Module?
                            Last edited by ALINE_M5; 02-14-2013, 05:54 AM.

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                            • #15
                              Next time your car dies and won't start, try pulling the plug wire off of the coil, hold it close to the coil contact, have someone else crank the engine, and see if you get a spark jumping from the coil to the wire. This is an easy way to see if the coil is getting power and firing. This won't tell us exactly what is wrong, but can help with the trouble shooting.

                              I had a similar problem on my car years ago. It turned out to be a hairline crack in an inline fuse near the battery. My car has a fuse in the wire bundle running from the battery. If I remember correctly, it is wrapped in with the cable making it hard to find if you don't know it's there. It's built into the wire bundle and is not a plug-in type of fuse. The fuse protects the ignition system and maybe more (all of the too ECU maybe? I'm not sure). Anyway mine had a crack in it that would open up and kill power to the ignition system. The car would still crank but it wouldn't start. When it cooled down, the fuse would bridge and the car would start. This was an UNUSUAL failure. I doubt that it's what is wrong with your car. The main relay and ECU mentioned earlier in this thread are more likely culprits.

                              Good luck,

                              Brad

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