Test Crank [Archive] - Bimmerfest - BMW Forums

: Test Crank

07-02-2012, 01:50 PM
A method to test spark is to remove the coil and plug from the cylinder, with the plug attached to the coil ground the plug and test crank to verify spark.

1. How do you test crank a vehicle with a push button starter?
2. How do you test crank a vehicle with a push button starter without physically accessing the starter motor?

07-02-2012, 05:55 PM
I'm not sure if this is a valid test for your BMW. In most modern BMW's if you have good compression, a spark and fuel supply to any cylinder and no sensed resulting combustion you will get a fault code for that cylinder and your ECU will essentially shutdown that cylinder (no spark, no fuel) until the fault code is cleared to prevent further damage. I am not sure how many cycles before the cylinder shuts down but I'm told it will...

07-03-2012, 09:24 AM
I don***8217;t understand your answer. Maybe I should rephrase my question. How do you test for a valid spark? If I get a misfire code for multiple cylinder and I suspect the coil for cylinder 1 is faulty. How do I condemn the plug or coil? Assume the following is true:
1) Coil has valid power voltage and DME signal for ignition.
2) Switching coil and plug to a different cylinder is not an option.
3) Replacing the coil and plug with new parts isn***8217;t cost effective.
4) Resistance value of coil is a few ohms out of specification.

07-03-2012, 12:29 PM
Check out this video: