Question for any Motronic wizards.

[Keith Turner <kturner@xxxxxxxxxxxxx>]

   I'm having an intermittent problem with my 88 325iC.  The problem is not 
dependent on weather, speed,  amount of time the car has been running, or 
time of day :)  The car can go for a couple months with out seeing the 
problem, and then have it happen a couple times one day, then it won't 
happen again for weeks.  I'll be driving the car and then the engine will 
just shutoff.  I'll wait 10-15 seconds and it will start right up like 
nothing ever happened. There has been one or two instances where the engine 
just "blinked" off, for less than a second and then kept running. There 
have also been a couple instances where the car would not start (from being 
parked), and I had to wait for a couple minutes, then it would start right 
up.  This behavior has been going on for probably a year and a half.
   When the engine cuts off, the tachometer drops to 0 almost instantly, 
even if the clutch is engaged and the engine is still turning.  According 
to the Eleltrical Troubleshooting manual the tach gets its signal from the 
Motronic control unit.  The only signal I see going into the MCU (with 
regards to engine speed) is on pins 47 & 48 which is the engine speed 
sensor.  That seems to tell me that even if the fuel and/or igntion 
sections of the engine had a fault that the tachometer would still work 
(provided the fault wasn't the MCU), can anyone verify this?
  I can tell when the engine is ready to start again by the dash lights. 
 The indicator lights in the instrument cluster will all turn on, just as 
if the key had just been turned to the  run position (from off).  At this 
point the engine starts with no problem. I don't know if this points to 
anything or not.  Maybe its the default startup for the MCU?
 Are there any cases in which the MCU will wait a certain amount of time to 
begin operation again (say after loss of power)?  I'm starting to think the 
problem is in the MCU, and/or wiring to/from the MCU.
 Anyone have any suggestions or information that might help me track this 
down?

Thanks,
Keith
BMW CCA# 162807
88 325iC
77 320i

------------------------------