Nissan Repair: no spark, crank angle sensor, crankshaft sensor

Question
QUESTION: after replacing upper crankshaft sensor due to engine stalling and/or not starting and clearing all fault codes car still will not start. I checked to see if it was getting spark from plug and found no spark. Battery , alternator and starter are getting  power. What is my problem

ANSWER: Terry,

The upper one (sensor) is the cam position sensor.  This fires the injectors.

The lower one (sensor) is the crank sensor and that is the one that fires the plugs.

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QUESTION: But I am not getting a fault code from the computor

Answer
Terry,

The crank angle sensor is the usual suspect.  Now, if it is not the crank angle sensor it is usually the transistorized amplifier on the strut tower.  You are going to have to back probe the circuits to determine where it is not getting power or signal.  These will not throw a code.