P0300 Strange Issue

[silentdub]

09 370Z 100K Miles

Getting a P0300, after reviewing the data stream, everything seems normal, no out of range readings. We can reproduce the issue and on the misfire counter, we can reproduce it only at 50% throttle.

We are getting misfires on bank 1 only, bank 2 is fine. When at idle, no misfires, when at WOT, no misfires. When at 50% throttle, we get the stumble and the misfires are physically noticed and counted on the data logger.

There are no codes other than the P0300, no MAF or TB Codes.

I am leaning toward an issue with bank 1 TB but that would just be a guess.

The one thing that is troubling me is a ‘long crank’ when starting especially when cold but the car cranks longer that it should before starting. I have found this issue with ?Nissans to be an issue with the crank sensor in the past but combined with the misfires as noted above, that doesn’t make sense.

Thoughts?

[VStar650CL]

I agree it probably isn't a sensor issue, Halls generally screw up at very low or very high RPM but rarely in the middle. Your hunch about TB1 seems likely. I'd try a good cleaning and then an IAVL to recalibrate the MAF's.

[VStar650CL]

PS - If the car is driven like grandma, you might also want to decarbon the engine along with cleaning out the TB.

[silentdub]

I see the one issue possibly being related to the Throttle Body, but the long crank not so much.

[VStar650CL]

They could both be from the TB if one side is suffocating at drop-throttle. See if giving it some slight pedal eliminates the long crank.