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Old 07-29-2009, 11:23 AM
gahawkins gahawkins is offline
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Location: Rochester, NY 14506
Join Date: Jul 2009
Posts: 21
Mein Auto: 1991 M5
Ignition Question

I suspect this question below pertains to many BMW engines, although the sensors and the leads from the sensors differ slightly Model to model. Any philosophical advice appreciated; or suggestions on other forums to post such questions!

My 1991 E34 M5 has a broken "cylinder identification" sensor. This device appears to be a toroidal coil on the #6 ignition wire, which apparently provides an inductively sensed pulse to tell the DME (engine management computer) the cam position - ie are we firing on the exhaust or the compression stroke. The car runs fine, despite this disfunctional part. So my question is: what is the ignition spark doing? Same for the fuel injectors, which are usually timed to the cam shaft position?

For example, is the ignition firing on both the exhaust and compression? Or after starting, does the computer gues a cam position and check whether the engine keeps running of begins to slow? Why would one need the part if the engine seemingly runs so well?

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