370z delayed intermittent start failure.....
 

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. :confused:

If it cranks at normal speed, then I suspect an electrical problem (ie, clutch switch tests good on bench but fails when installed, wiring, etc). If it cranks sluggishly, I'd look at the battery condition and the battery terminals.

Thanks SouthArk. Looks like I'll be rooting through wiring. I'll update as I progress.

I had the same issue with mine. I (like you) tested the clutch switches and found that both tested OK with a multimeter. However, for the $35, I decided to replace the upper switch and the problem went away IMMEDIATELY. Have not had any issues since replacing 2 years ago.

I would replace the upper and see if the problem remains. If it does, you can eliminate one of the concerns.

Appreciate it! Noted, I am going to replace that.

On another note. Am I correct in assuming that you can not service the starter relay or ignition relay within the IPDM? And if so, I cannot simply buy a replacement IPDM, but must take my Z to the dealership for a replacement? (assuming the upper clutch switch does not resolve the issue)

the saga continues
 

So both clutch switches have been swapped out and still no turnover.:/.....

Going over your thread you’re missing one of the most essential part you haven’t checked that starts the car which is the starter. If no codes have been thrown, then the battery and the starter should be the next focus with slow/no crank symptoms especially when she runs good once started. High amperage drawing starter will eventually kill the battery. Any shop should have proper tester to check for excessive starter draw. Last post you say still no turnover. Jack up the car to get to the starter and tap on it with a hammer with some kind of extension/pry bar and try to start the car. Do it several times to see if it gets it going. It may be the starter or starter cable with high resistance or even something else but you just have to eliminate the basics before you get deep with diagnosis. And sometimes it just better take it to the professional rather than throwing parts at it and hoping for the best. Just because someone had similar issue it doesn’t mean the solution is the same. My 02 cents

Thanks Fryzia23. Unfortunately I simply didn't have the jacks or stands to get under her so all I could do was check switches, fuses and what not. After I exhausted all available options I had her towed to the dealership this afternoon. Should know more soon. I appreciate the input.

Good news bad news.

-Good news, it wasn't the IPDM.

-Bad news, they bent me over for more then $800:icon14:

Live and learn I guess. I immediately went out and grab jack stands and a solid jack, would have easily paid for itself, just didn't want to be that guy wrenching on his car in an apartment complex parking lot. Well, thanks everybody, appreciate it.

So what was the issue?

:iagree:

:confused:

Starter?

I know this thread is a year old but i'm experiencing the same issues as you with the same model year and roughly the same mileage. What was the issue ?

If I can add I would clean the main grounds from battery to chassis and chassis to engine. Make sure stater is bolted on tight. Lastly if your car is a 2011 then I would remove the starter and have the starter itself checked as the solenoid contacts are probably worn by now.