635 CSI, no spark.

Mind died about 200 yards from the house. Pushed it to the driveway. Diagnosed as no spark.

Where's the most likely place to start. All the fuses are good.

Crank position sensor wiring. It's real easy for it to get caught in the water pump pulley.

Otherwise check the distributor cap. They are kinda of a pita to change, so they get stretched out beyond normal service life.

A little more esoteric, the solder joints in the dme start failing over time, eventually cutting spark. More of a last resort, but it happens. Another board member had this issue with his m5, I had it with my e28. Re soldering the main board fixed it.

I second the CPS as the most likely cause of sudden loss of spark, but I thought it was on the bell housing (early Motronic M30s had two sensors, but later ones may have had only one - I can't recall).

If it were me, I would do the distributor first, unless I had replaced it in the last five years. It might fix the problem, and even if it doesn't, it would likely save me from being stranded in the next few years. Bleeping front-mount Bosch unit means I would probably need to drain and pull the radiator, but my cars are usually overdue for a coolant change anyway, so . . . .

If I could find another Motronic box cheap on Ebay, I would buy it and try that next, because it's good to have a spare Motronic box around. Every time something else goes out with the ignition, I have a spare, and I can swap the boxes to see if that's the issue.

I would check the impedance on the coil, because it's easy and rules that out.

Then I would try a crank position sensor.

One time, even after I did all that, I still didn't have ignition. Turned out the magnetic pickup sensor cable on the plug wires had given up the ghost.

I have used this guide, usually with success, in addressing early Motronic ignition issues. http://www.hiperformancestore.com/motronic.htm

Jamey_from_Legal wrote: If it were me, I would do the distributor first, unless I had replaced it in the last five years. It might fix the problem, and even if it doesn't, it would likely save me from being stranded in the next few years. Bleeping front-mount Bosch unit means I would probably need to drain and pull the radiator, but my cars are usually overdue for a coolant change anyway, so . . . .

Distributor in this thing is just a rotary switch - there's no sensors in it whatsoever.

The items involved are the crankshaft position sensors (there's two of them, aimed at the flywheel), ECU (DME), coil, and the wiring between them. GRM recently had one where the pin that triggers the crank sensor fell out of the flywheel.

No doubt, there are no sensors in the distributor.

But, I have seen more than one develop conditions that I could not observe by inspection, and kept the car from making spark. And replacing the rotor and cleaning the contacts didn't resolve the issue. The darn things wear out, and your motor won't run.

Is there fuel, or both out?

There is fuel, but no spark.

Here's the deal. The car was driven 200 miles by my 27yo son and died 10 miles from the house. After 30 minutes, it re-fired and made it the last 10 miles, less the 200 yards and died again. We pushed it home.

After a week or so, I found time to troubleshoot it. No spark, but it is getting fuel. That's as far as I have gotten. Now that I've asked the hive, it's been raining and I haven't had a chance to check any of the suggestions.

I'm about to give it to my 16yo and let him fix it. It's not my favorite car and a old BMW should be quite the learning experience. Probably make a pretty good first car as well.

Does it have the onboard computer on the dash (the thing that displays time, temp, mileage, etc.) If it's like my M535i there's a security function built into the OBC, where you can punch in a code to disable operation of the car via a relay that's inline with the main relay.

Anyway, what can happen is that relay can become intermittent, so it opens up randomly and then kills the car. It happened to my car some years ago and drove me nuts until I figured it out. The fix was to simply bypass that relay with a jumper wire, and it's been fine ever since.

There's a more complete description here: http://www.mye28.com/viewtopic.php?t=37809

Dam that is one lucky kid those are getting hard to find.

Wiggle speed and reference conectors at the harness. These tend to crack at the conector and the wires in the cable are small and brake. Ohms on the sensors should be checked as well. Simple in the car test. DME resolder I a two beer job while watching the ball game. I have done many and it can solve all kinds of issues.

All this is predicated on the dizzy being good.

Sell it to me