So my Z had a battery changed about 1.5 years ago and it developed a starting issue. Prior to the battery dying, never had an issue.

Description of issue: So hot or cold rain or shine the car rarely/never start on the first attempt, takes multiple attempts to start. The engine turns over until the battery starts to lose some power and eventually starts. ( sometimes it take 5-7 attempts sometimes i get out of work and im stuck in the parking garage for 15 minutes trying to get it to start.)

What has been done:
Changed fuel pump with DW300 pump
Changed all cam and crank sensors with OEM brand sensors
Changed spark plugs
Added fuel gauge to monitor and confirmed that Im getting pressure
Exchanged battery
Cleaned and replaced grounds, even added a few more just incase lol
Changed throttle body
Did relearn/pedal dance
Check power at the injector plug (WAS NOT GETTING A SIGNAL AT THE PLUG UNTIL IT WAS READY TO START)
Checked coil packs for spark
Confirm fuel pump is working properly
Check all fuses and relays to assure no issues there.
Changed VTC solenoids

****About the car. Its a 2006 Nissan 350z DE VQ that has 47,000 miles on it, was automatic when i bought it and did a CD manual 6spd swap. Drove perfect for months, no issues. The battery started failing and I changed it, thats when the problem started. When the car has not been driving overnight it's easier to get it to start. After driving it to work which is about a 35 min drive, the car takes forever to start(recently decided to start driving it again as being stuck in a parking lot is plenty of motivation to fix this)lol.

I have noticed that when the battery loses charge, it is almost always easier to start. Im thinking maybe I have a bad ipdm or a bad ecu. The car gives no check engine light for anything but a o2 sensors(wideband O2 sensor installed). But that was like that before and drive/started fine.

Only mods done to the car are:
Intake plenum spacer
DW300 fuel pump
Manzo test pipes with isr exhaust from test pipes all the way back
k&n drop in filter
Street pro Series clutch and lighten flywheel.

Thats about it, anything you guys can suggest to make starting this car easier would be greatly appreciated!!! Thank you in advance!!! If I forgot to mention anything let me know. Ill be checking in every 2-3 hours daily in hopes that someone has a miracle up their sleeves!!!

 

You've done some extensive work on the car. My 1st question is who tuned it. (If you're running test pipes it's assumed it's tuned). Since the main difference is whether it's been driven recently I'd do a resistance (Ohms) test on the coolant temperature sender both when cold and hot. If it's 0 or infinity change it out. Gl!

 

It got OEM headers and no tune. I have already changed the coolant temp sensors on my first journey to fix this thing lol I did finally get a check engine light for the crank position sensor yesterday. I'm going to test the sensor and the wiring to the crank sensor today. Do you know what the specs are I should be getting?

 

https://www.google.com/search?q=2006...ile-gws-wiz-hp

 

Thanks!

 

Wouldn't hurt to put a vacuum guage on the intake manifold. It should read steady at 20+.

 

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