370z delayed intermittent start failure.....

ViciousZ34

So here is the low down for my daily driver 370.....

Please feel free to correct me on anything that I am wrong on in my attempts to resolve this, I welcome the constructive criticism.


Model: 2011 370z touring sport manual, tech nav, roughly 71000k, 2nd owner bought her at 21000k in 2015

Mods: Berk HFC, FI non-res exhaust, Z1 CAI, Z1 rotors, nav bypass for video while in motion, 4th brake light, ARK GT-S springs, and various cosmetic mods. No tuning has been done to her as of yet.

Issues: When intermittent start failure arises.....Upon attempting to start the car while pressing the clutch pedal, ignition rolls through lock>acc>start and either ticks once and fails to start, no turnover, no crank or sometimes starts with extreme hesitation and delay.

When she does run, she runs perfectly and has never stalled on me or died in motion or at a light.

This is intermittent and has been occurring randomly for the last several months with increasing frequency. Sometimes she will fire up perfectly for weeks or even months and then spells of the above mentioned behavior begin. I am in KC and the weather is still warm and stable temps.

Attempted fixes/resolutions:
-No CEL, Key, or any other dash light is active that would not normally be there
-All batteries for key fobs have been replaced
-Behavior is the same either seated in the fobgina holster or not
-Steering lock has been checked, this model has already had the resolution applied at the factory in which case the fuse does not and never did exist, I am also able to roll to acc>start every time (unfortunately she doesn't start every time:/)
-Battery has been replaced with a new cell in the last few months
-Lower clutch switch sensor has been replaced
-Upper clutch switch sensor replaced

Things I have yet to try:
-Crank position sensor (though I would expect whacky behavior while the car was running if this was the issue)
-Coil packs (also would expect misfiring if these were faulty)
-Spark plugs, (again would expect misfiring)
-Fuel injectors, (but when she runs, she runs great)

Like others have stated in various threads that I have read attempting to chase down the issue, I have yet to be completely stranded. With enough attempts I can eventually get her started but I am concerned of the excessive wear and strain this puts on various systems as this was not intended to stand this level of abuse whilst firing her up.

Tomorrow I'll be grabbing a OBD scanner and seeing if shes throwing any error codes but beyond that I am stumped. I really don't want to take her to a dealership, I am extremely connected to the car and absolutely disdain the thought of leaving the Z in someone elses hands ( to this day the Z has never been parked next to another vehicle, if that gives you an idea of how much i don't want to leave her somewhere out of my sight).

Anything the excellent Z pit crew here at the370z.com could enlighten me about would be excellent.