BMW Repair: 1985 318i Fuel injector problems, 4 cylinder cars, crank angle sensor

Question
I have a 1985 BMW 318i. Refurbished the engine, but someone
put in the battery backwards before getting the car restarted.  

Fuel, Air and Spark are all ok, it will chug with the gas from the
Cold Start Injector, but won't start. My only guess is the Injectors
(new) are not getting correct signal.  

I've been working through the Bentley Service Manual, with a
multi-meter, and have found the injectors' voltage is ok, as well
each is grounded ok, but there doesn't seem to be any pulse at
the injectors.  

All the electrical checks at each of the main electrical
components seem to be ok, which Bentley tells me means I need
to replace the component. I'm wondering if anyone has any
advice on which component to start on or other things to check,
as opposed to trying/buying all new electronic components.  

Thanks for any help or advice you can give. Ben Kremer

Answer
Ben,
 I'm not as familiar with the 4 cylinder cars as with the 6 cylinder cars, but I'll try to help.

 You should have a timing sensor on the Harmonic Balancer, flywheel, or in the distributor.  If this sensor is bad, the computer doesn't know where the engine is, and cant send a signal to the injectors to fire.  I think this sensor is located in the distributor on the 4 cylinder engines, while its usually on the harmonic balancer on the 6-cylinder engines.  Look through the Bentley and see if the mention anything about a timing sensor, Crank Angle sensor or any other timing device.  

 Of coarse, your ECU (Computer) could be shot as well, however this is unlikely.

 There are alot of the 4-cylinder guys on www.bmwe30.net that can probably help you more than I can.

 Hope this helps,
 Josh