Ignition Problem- No Spark- '85 325e

[TaylorSp]

I'm trying to get a friends 04/1985 325e running again. It sat for years and after a little work we got it running again, but after a week of sitting it no longer starts. We have tried about everything following the troubleshooting flow charts we can find and cannot seem to find the issue. The car cranks, ICV buzz's, and fuel pump runs, but there is no spark. We tested the coil and 12V at green wire and both were fine, but we went ahead and replaced the coil anyway. We replaced the crank position sensor, and the reference sensor tested ok according to its resistance. We also checked for the raised tab on the flywheel and that seemed to be there. The spark plug wires are new and in great shape. We connected a park plug to the king plug wire and got no spark their either so it is not a distributor issue. We replaced the computer which had no effect.

A post in another forum suggested using a test light on the negative terminal of the coil:

"Take a simple test light and place it on the negative side of the coil, crank engine..

Light flashes= This means the ECM is putting out a timing signal for the spark and injectors. This tells you within seconds if the ECM is receiving timing signals from the crank sensors.

Light NOT Flashing= You have no spark or injector signal.

Check sensors, powers and grounds."

We tried this and the test light was on solid as it is with the green wire. So, the question is if it should be off and flash on, or on and flash off? Should there be solid power from the negatives terminal of the coil?

Thanks a lot in advance!

[DesertBMW]

I had similar problem on my '86, I was not getting spark when tested at the spark plug wires. Then I pulled the wire from the coil and coil produced the spark. It ended up being stripped timing belt.

[TaylorSp]

I see. Ours does not produce spark at the coil, so it probably isn't distributor/camshaft related.

[jlevie]

If there is power to the coil, but no spark when cranking the cause will be a DME that is bad or not running, a lack of timing reference data to the DME, a fault in the wiring between the DME and coil, or a bad coil.

[603Racing]

There are the two sensor connectors that are located on the top of the valve cover at the back of the motor. They are identical and can easily be confused.

Some early eta's had a security feature that worked with the OBC (as do e24's and e28's). There are two wired connectors that go to the OBC Relay Box (little black box) just above the hood release handle behind the knee bolster. The obc can be used to disable the car. If there is a short in the wires in these connectors the car will not start. I forget the specifics of wire colors, exact disabling fuction, etc., but I do know you can jumper two of the wires together to bypass it. I did this on my 84 eta. Here's a link to my recent no-start thread.

http://www.r3vlimited.com/board/showthread.php?t=301272

I had more than a OBC Relay Box issue, but it was definitely part of my problem. My second post in that thread has a link to the OBC fix.