Hi guys I am back! It's been 20 years since I first bought my G35 Coupe new from the dealership. I still love my car just like my screen name says. Just that recently it doesn't start occasionally.

It's a Coupe 5AT. It only has around 50k mile on it. I kept many years in my garage. Only drove a few months here and there.

​​​​​​I have done all the oil changes. Did a coolant flush, ATF flush, replaced the thermostat. Battery replaced twice. I see cracks at the belts but will replace it soon.

So my problem is there one time it doesn't start on the first crank. But okay on the second attempt.
Another time I cranked it for 5 seconds and didn't start, I turn it off and started on the 2nd attempt.
Then there's a time I tried to start the car and the whole car black out as if the battery was dead. So I turn it off，prayed for a few second and tried again and it started. I first thought it might be battery related but I check the battery is full when I tried to charge it.

What do you guys think? Starter problem or spark plugs?

Thanks 🙏🏻
ILuvMyG35

 

Could be a crank sensor that is failing intermittently.
my audi did this for years before showing a solid fault.
I am not sure about the g35.

 

It could need a throttle body cleaning.