87 535i Ignition Problem

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. >>

You have electrons at the battery, jah? Where do they stop exactly?

Even a flat battery will still have ~50,000,000,000,000,000,000,000,000,000 electrons in it, but they won't want to go anywhere!

When my 635 did this is was a bad connection to the Motronic TDC sensor on the bell housing.

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...

Thanks for the advice. I'll inspect that sensor.

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?

Any comments would be appreciated.

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...

Thanks, your feedback is appreciated.

Thanks. That really helps to know that. I'll keep looking and keep posting.

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.

Thanks to everyone who assisted.