I have a 1988 780 (v6) with the famous intermittent start problem. I have changed both the fuel injector relay and the radio suppression relay with no effect. The car usually starts right up in the morning but once you drive it it has to sit awhile.
I checked the voltage between the negative lead of the distributor and ground while I cranked it today based on and old tip from Myles Cullen to test the ignition amplifier. I got a voltage, which dropped from 12 v to around 8 volts (the battery was getting low from cranking), but I didn't see any pulses at all. Does that mean the amplifier isn't triggering?
I do really know how the amplifier works, but presume that it is triggered by the crankshaft sensor.
I measured the resistance between the terminals of the crankshaft sensor on the bellhousing. Between the center and one side I got 586 ohms. Between the center and the other side I got nothing. Is the sensor bad?
What else should I check?
Thanks.