2004 Nissan Murano loses power and misfires when engine warms up but throws zero codes. Is it old coils or bad o2 sensors?

Spark plugs were replaced and gave the car a boost but when the car has been running for awhile it starts to get sluggish and engine hesitates a bit when accelerating. 

2 Answers

  • 4 weeks ago

    Nope, bad maintenance. Likely one or more plugs are not properly torqued in the cylinder head and are loose and wobbling around. Not a big deal but you lose compression. MAKE DARN sure that you installed the CORRECT spark plugs. Parts dudes have handed customers the wrong plugs in the past and not knowing the difference or comparing old plugs to new plugs, people have installed them and don't realize it until the pistons smash into the new spark plugs that were the wrong depth.

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  • Anonymous
    1 month ago

    Do not guess.  Test.

    You will need a dealer level scanner, an o-scope, a fuel pressure gauge and a multimeter.  Check  O2 sensor operation.  Check misfire counts when the engine is misfiring.  Check coil and injectors  current ramp with a scope.  Check fuel pressure when the engine is warm.  Check injectors and coils resistance when the engine is warm.

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