e28 ignition woes

[K F Martin <kfmartin@xxxxxxxxxxxx>]

hello:

could someone please offer me some troubleshooting advice 
regarding an ignition problem with my '87 535is?  i dont 
seem to be doing very well on my own...just spending too
much time and cash...

i recently installed new cap, rotor and wires, so when the 
car wouldnt start i first checked for spark at the coil.
no spark, but it was getting 12v, so i did the resistance 
test on the coil as per the haynes manual.  i found it to 
be slightly out of spec, so i replaced it, anxious to fix 
the problem and jumping too soon...but the new coil didnt
improve the situation...still no ignition.  

...going down the troubleshooting list, i next checked the 
sensors.  i found the reference sensor to be open between 
connectors 1 and 2, where it should be 1k ohm, so i replaced
it thinking surely i had the problem solved.  unfortunately,
this wasnt the case...the car didnt start.  ive got spark, 
but its extremely weak.

the new sensor meets the resistance check.  the new coil is 
no better than the old for resistance...about 25% high on 
the secondary.  the coil is getting its 12v and a test light
on the negative terminal while cranking shows current being
interrupted; the light flickers.  the battery is fully charged.

i suppose i should go after the motronic unit next, but before 
i tackle that great unknown, i thought id inquire of those who
have possibly been down this road before.  i cant understand 
why it wasnt the sensor...why the motronic unit would fail 
at the same time...and i dont know if those coil resistance 
readings are a big deal.

i would Greatly appreciate any advice on this.  Thank You for 
your time.

kurt.

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