2003 350z car won't start!!!!
 

I have a 350z with 117k miles. I have been dealing with this problem for over 6 months and the nissan dealership, my tuner shop, nor I can figure this out. So the problem is on warm starts sometimes it will start and other times it will not. Example: If I drive the 350z to 3 places 15 mins from each other and only stop for a few minutes at each place by the 3rd place I will have to let the car sit for an hour in order for it to start. IF I don't let it sit I can crank and crank; it tries to turn over but can't. It also has no problem making a cold morning start the next day. No engine check lights come on and no codes. Everything looks to be running in factory spec when viewed on a OBD scanner. I do have a aftermarket intake and inspected the MAF sensor and it looks to be clean.

Parts I have replaced in the last 6 months:
Crankshaft position sensor
Camshaft sensor bay 1 and 2
Starter
Positive and negative battery cables
Brand new Battery
New Spark plugs
New Coolant sensor
Hi flow cat converters (broke the stock ones)

Also have read articles like:

https://my350z.com/forum/maintenance...-randomly.html

Clutch switch sensor seems to be working fine too.


Thanks for all your help this has been really frustrating

Welcome- it sounds like you've put a lot of research and effort into this. Also, a lot of parts replaced, which I assume are due to codes you've found? What codes have come up in the past? Also, are there any codes currently when your Z is in the NS condition?

In the past I had crank and camshaft sensors throw codes that is it. No codes show when car is unable to start. I bought this car used from a dealership so I don't know what maintenance has been done but car runs and drives great. No rough idle or anything weird.

There is a random computer/NATS issue that affects early models. It has been intermittent for me for the life of the vehicle (will go literally years with no issue, then all of a sudden wont start), and is cured by locking and unlocking via the key FOB (some say flipping the key works also). Best i can tell the problem seems to arise when im around other Nissans.

Mine problem is pretty consist if the car is driven for a hour it won't start. I did flip the key and lock and unlock the door. I was unable to get that to work. Is there a specific order?

Prob not the NATS/computer issue then. This is where knowing the vehicle history, any water damage, alarm/stereo work, etc is helpful to understand where to proceed with the diagnosis.

Also where a dealership/scan tool diagnosis might be your easiest bet to understand what is going on behind the scenes when you are trying to crank during the no-start condition.

Are you getting fuel, spark, compression, etc? A scan tool would be the quick way to verify all the old-school tests that you had to do to trace back an issue. For example, if you can verify you aren't getting spark during the no-start condition (but you are getting fuel and have good compression), then you work back through all the systems that would prevent you from getting a signal to your coil packs. Etc, etc, etc.

Sounds like it's not going to be easy to get the conditions right and be in the right location to perform the diagnosis, but unfortunately that is your only option.