BMW Repair: DME wiring Harness, speed sensors, 325is

Question
I have an '88 325is.  It has about 160k miles on it, and i've been doing all of the regular maintenance in the engine and driveline.  It has been running great, but all of a sudden (over night) I started it up in the morning and instead of idling at about 600-800 RPMs it was revving between 1000 and 2000 RPMs by itself, i drove it about 20 miles and turned off for 8 hours (work) then i started it back up and it was revving in the same way.  Then it turned off and wouldn't start after i drove it about .5 miles.  I have checked the computer's engine position and speed sensors and both seem to be in working order.  Basically there is no spark coming out of the coil for the spark plugs (checked that too.)  A BMW mechanic said that it could be a ground in the DME wiring harness.  So any input that you have would be greatly appreciated, maybe a 1988 wire diagram would be helpful? do you know of how i could obtain one?

Answer
Mike,
 The best thing you could own, if you do your own maintanence is a Bentley manual.  I had a Haynes for a while, but it was pretty vague in it's descriptions.  I bought a Bentley, and it solve that problem.  If you plan on keeping the car... it would be a wise investment.  It also has the wiring diagrams too.

 There might be some diagrams on the net that you could run across, but I've never been that lucky.

 I would check all your grounds to the engine, and the wires on the battery.  Sometimes they get loose, and go bad.
 
 Also there's the possibility that your DME is shot, and you just need a replacement.  That would be my first shot, I would have a fellow E30 owner lend his ECU (DME) to you to try it out.  If the car runs... then that's the problem.

 Good luck,
 Josh