Hi, I am experiencing a hard startup on my 2007 350z VQ35HR, it is fine when I startup the car in the morning(first startup), no problem at all. But after driving it for 20-30 mins, i shut the engine and come back after an hour, then the hard startup will happen, it will fail to startup few times before it is successful. And when it starts, the RPM will almost drop to 0 before it finally bounces back to 1000. There is no signs of RPM dropping when i drive the car, all normal. Anyone experiencing this too? Remember, it is fine and perfect for the first startup

I only have Amuse exhaust modification.

 

Check engine light on? Sounds like a cam/crankshaft sensor issue.

 

Check EngIne Light Off

 

1000 is high idle FYI. Agree with above - cam position sensor probably or crank sensor possible.

 

But it is fine when on the first start up and the engine don't seem like dying while I am driving the car

 

This may sound stupid but you can always give this a shoot..Well you said Hard.. what do you mean by hard? hard sound? or hard as in tough to start? ...my battery was almost dead..

Easy to start in the morning hard later through the day.

 

Those were my symptoms when my cam position sensor failed. But it DID throw a SES along with the CPS code.

 

It is hard(tough) start like a very old car starting its engine which takes a very long time. Sometimes it will fail then i have to turn the key to off then turn on the engine again. But this doesnt happen on my first cold start.

 

Did you fail to start the car when it's cold? Because mine is fine in the morning when the car is cold. What is SES and CPS code?

Let's say it is the cam/crankshaft sensor is the problem, will that cost me much? and is it hard to replace those sensors? I am not that good with engine knowledge.

 

What about Fuel Pump and bad spark plugs?

 

Service engine soon. Crank/cam position sensor.

Sometimes sensors fail when they get hot. Your first morning start the sensor is cold. Throughout the day the sensor gets warmed up. Contacts/connections inside the sensor could be coming loose once warmed up. Best way to check is with an ohm meter cold and then when hot. You probably have a pending code.

The cam sensors are simple to change on these cars. Crank I'm not sure where its located. Most cars its behind the crank pulley but it can also be near the flywheel.

 

Hard starting when hot is usually a cam sensor on Nissans. 0jiggy0 has the right idea as far as testing the sensor when hot and cold. It could also be the fuel pump, fuel filter, spark plugs... A whole bunch of small stuff. But the fact that it starts fine when cold and runs fine, I'd start @ the CPS.

 

yep like stated above sounds like cam sensor which is easy to replace i'd rather replace a cam sensors that spark plugs lol. crank position sensor is on the passenger side of the trans bell housing at roughly the 2oclock position in line with the flywheels teeth, u can reach up there from the bottom or from up top your choice. +1 with what 0jiggy0 said, ohm when hot, find service manual and see what the specs are, if out of spec then you found your problem. whats the milage on the car?

 

I have tried cleaning the Fuel Pump, it starts ok now but will drop to almost 0 RPM before it starts to bounce back up, if it still happens. I will try check on the CPS. I will report back when this happens again after the CPS is replaced

 

Why not check it before you automatically replace it?

 

Do you pump the gas pedal to start it after its hot

 

Yeah, no sense in just buying parts for the sake of buying parts... Besides, testing it will take about 1/3 the time it takes to swap it.