My Z won't crank at times
 

Ok so, I had a problem not so long ago with my starter for the Z. I replaced that new and I even bought a spare key I needed for the car. Everything is fine now, my car will crank on the first try but not all the time. It happens at random even with a new starter, new chip key it still randomly won't crank at times. Ik how to make it crank when this happens like I would take the key completely off and put it on ACC until my whole dashboard turns on the it'll crank. It's not that I'm turning the key way too fast, I even give it time and sometimes it won't crank. I'm wondering if there's something I need to check or is this just a common problem with a 03 Z. It's not like this is a daily thing but sometimes when it happens I just wish it wouldn't and it'll start up on the first try like nothing

I had a similar problem with my 300ZX. First, go to an autoparts store and have them test your battery, starter and alternator. Yes even the starter sometimes parts are defective, the probability increases depending on where you bought it. They will test these for free while they are still on the car. Also check and make sure there isn't corrosion/oxidation on your battery terminals and on the starter cable. Let us know what you find after doing this.

The key has zero to do with cranking, if what you mean by cranking is the engine turning over. The chip for the anti-theft controls the engine actually firing up, not turning over; it will turn over until the battery dies or the starter burns up. So, your car DOES turn over all the time, it is just rarely it won't actually start - correct?

Yes that's correct, it turns over but rarely at times it won't start up

Does it randomly die also?

I am leaning towards cam sensors

No it doesn't die on me, just won't start up rarely.

Still leaning to the cam sensors

I'm leaning to a failing anti-theft system. Common problem on the early years getting up in age and annoying as hell because there doesn't seem to be a one size fits all fix. It's a hit and miss problem.

One other thing - it simply annoys the hell out of me that car guys can say "it doesn't crank" when the engine is actually turning over. But maybe I'm just getting old and cranky....so to speak.....

Same issues...
 

I have a 03 350 also, same problems for a couple months. It's a faulty crank sensor

That should throw a CEL - did it? And are you saying you replaced yours and the problem went away?

my buddy had a bad cam sensor and it never threw a code

Hence my question....and I had a bad cam sensor and it did throw a code. I also don't believe anyone can positively identify a problem/solution such as this one without further information. But I appreciate JEM's 1st post anyway, lol.