Looks like you've been flailing along quite nicely (flailing = waving arms and throwing parts at the car in the hope that this will fix it. Eventually - if you replace the entire car - it will, and of course the last thing you replace will be the problem component.)
The ignition relay is certainly a failure point - and not horribly expensive to replace if you're going to flail. I'd prefer to check the output of it with a voltmeter before spending the money, but if diagnostics aren't your thing and your wallet is deep.. go for it.
The ignition switch is an unlikely point of failure IMHO.
I also experienced a failure of the Motronic in my old '87. They have a failure that isn't uncommon of the solder joints in them that eventually failing due to heat cycling. It's usually one of the output transistor joints. A used one off a wreck fixed mine, then I disassembled and resoldered ALL the joints in the old Motronic - and tried it in the car. It worked fine after this.
If you loose all spark - it is very unlikely to be plugs, or plug wires, or cap. These might cause loss of spark at one or more plugs - but not all 6. Total loss could be rotor, might be coil - but all of these are simple to check with an inductive timing light (or a simple neon ignition tester) - saving you a whole bunch'a money.. but like I said, if diagnostics aren't your thing - dig deep and often, the dealer's parts department will become your friend.
No question about it: There's not a better Flailer than I, especially when it comes to this Bimmer. I do appreciate your insights and will indeed be testing the ignition relay next.
Thanks k>> I've got a 1987 BMW 535i that has some kind of ignition problem. >>
On my 325, this is known as the crankshaft position sensor and it will effectively remove all incentive for the motor to run. Mine had a broken wire at the potting compound and as long as the wires were still touching it ran but if you hit a bump in the road and the wire moved it would quit.Find this little sucker on yours and throw a meter on the connector, if it shows continuity, look elsewhere. If it doeesn't, replace it and I'll bet the car runs once again...
When I connect a voltmeter to terminal 15 of the ignition coil (and ground), I'm only getting a reading of 6 to 7 volts when cranking the engine. Should I not be getting a fully 12 to 13 volts to the Coil when cranking the engine?
Hey I seem to have the same problem. I finaly found the crankshaft position sensor and unplugged it and it starts up..but my car still wont start if I leave it plugged in...try it out ..it seems at least youre getting some response and help here so im also keeping trak of your page..It seems you have a bit older car so maybe its not the same issue..I think your car actualy does have a cold start injector while mine doesn't...
Hurray! Found the problem. I started fooling around with the Reference and Speed Sensor wires to see if I could see any chafing or other damage. It was not readily apparent, however, just for the hell of it I tried starting the beast and unbelievably she roared to life.
One of those sensors is flaky so I guess I'll replace it. Just got to find out which one it is.
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