Thanks Richard. This is where I was going next, but I had no idea which wires to resolder. I was just going to look for cold solder joints.

I'll let you know how it works!!!!

Mike
Check Ed Teller's website. Not sure of the address...sorry. I resoldered mine about year ago. It's easy. Take the ECU out. Take it apart. There are 2 printed circuit boards. You need to disconnect them to gain access to the soldered side. There's a big oval flange on one board with three leads on the board. Resolder these three leads. Flow new solder..and refresh. Reassemble. This is a common failure point for these units. My symptom was a very weak spark. Resoldering cured it!

Good luck!
richard

My 535i refused to start this morning. First, I blamed my wife for flooding it, then later I realized that there was no spark.

I'm going to swap the main relay with the known good one on her 528e (still running).

I have 12v on the coil positive.

All ignition parts, plugs, cap, wires, O2 sensor are less than 3 months old.

I remember seeing a post on resoldering the Motronic unit, but it's off the board now. Anything else I can try?

Thanks!

MikeL