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After sitting overnite engine turns over but doesn't fire.

(1997 Infiniti I30)
in Tuscola, IL on June 11, 2012
code reader had knock sensor bad. replaced it and its harness, along with the front crank sensor. fuel is ok but still no fire or spark.
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Popular Answer
of Greg's Orange Auto on June 12, 2012
agree w/miles get a diag and est as to not waste more $
on June 12, 2012
Customer Concern:
The engine will not start. It has no spark but does have fuel injector pulse.

1. At the coils, check for battery voltage at the Red wires while cranking, the Black wires should be less than 0.05 volts while cranking. Pin 3 at the coils (each wire color at the #3 pin are different) using a scope watch for a 3 - 4 volt pulse signal while cranking. Red wire - battery voltage, Black wire is a ground and the White wire is the signal circuit

2. If there is no pulse signal to the power transistors, using a scanner check the POS counts (Position) should be 179 - 181 while cranking. If inconsistent, check the signal plate (flywheel/flex plate) for damaged teeth. If there is an RPM signal and the POS counts are correct, this crankshaft sensor is good.

3. On the front of the engine, mounted on the oil pan is the crankshaft sensor (REF) reference. Check the AC voltage while cranking, should be a clean sine wave that indicates the Top Dead Center (TDC) position of each piston. White and Black wires in a 2 pin connector

4. Check the Camshaft (phase) sensor AC voltage output. This sensor should also be a clean sine wave. This sensor detects cylinder number. This sensor is located in the front cover facing the cam gear. White and Black wires in a 2 pin connector.
Tech Tips:
The engine will start (long crank time) if the crankshaft sensor (REF) is disconnected but if the camshaft sensor is disconnected the engine will not start (if the cam sensor is disconnected while the engine is running it will continue to run)
of Miles Auto Services on June 12, 2012
Camshaft sensor could cause your problem also. Most nissan products set knock sensor faults but that issue does not cause any problems.
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