hi guys and girls I'm new to this forum just want to figure out what's the deal with my G sedan. Ok i drive a 2005 infiniti G35x sedan awd auto trans. the problem im having is the car will crank but not start. Before it stalled out it would jerk and hesitate upon acceleration and try to stall out. i hooked my obd2 scanner to it and it had a weird code name 'manufacturer controller' so i cleared it and it won't start once. before i cleared the code it would start and then stall out now it just cranks.Now i know it takes 3 things to run an engine, air, fuel and spark. i can hear the fuel pump prime when the key is turned to the on position, so i suspect that there's fuel. i have compression, i can fell it by how healthy the cranking is. now i did buy new spark plugs and installed 3 of the six. im gonna finish today, ran out of daylight. but i tried starting it, again just out of curiousity and still nothing. i did use the flood mode technique to start it also because i suspected the spark plugs may have flooded due to the amount of previous start attempts. i changed the MAF sensor, Camshaft Position Sensor and Crankshaft Position Sensor. so im relying on my problem being the other 3 spark plugs i have yet to install. Just want some insight on my theory.

 

 

You can't flood this engine fortunately to that's basically a non-issue.

When you put the key in the ignition and turn the key to ON the car looks for the transponder chip ID on the key, if it's a recognized key the NATS indicator light on the left side of the dash will turn off when the key is in the ON position. If the security system does NOT recognize the key it will stay solid red when you turn the key to ON, it will also temporarily throw out the DTC code P1615 for an unregistered key. On the 5th failed start attempt with an unregistered key NATS will lock down the ability to start the vehicle and the code will switch to P1610 and the starter will no longer engage the motor when you turn the key to START. To clear the NATS lockdown you need to use a registered key and turn the ignition to ON three consecutive times and then the ability to start the vehicle will be restored.

If the ECM does not pass the NATS checks then the engine will CRANK but the injectors will not open and the coil packs will not fire the spark plugs

Once the ECM has a recognized key and there is no NATS interlock the start cycle basically works like this.

Key in ON position, ECM closes fuel pump relay for 1 second to prime the fuel system.

Key in START position, ECM looks for CKP (crank position sensor) and if found:
-ECM closes fuel pump relay
-ECM closes starter relay
-While the engine is cranking ECM uses data from CKP and CMP (cam position sensors) to determine when to open fuel injectors and when to fire coil packs.

It does not spray fuel or fire spark unless it has all the data to do so, therefor engine flooding is HIGHLY unlikely unless the entire rotating assembly timing is out.

By far the most common reason for a cranking but no start condition is NO FUEL IN THE TANK, the gas gauge on the instrument cluster is prone to failure and will display a half tank of fuel when it is actually empty. Put 1 gallon of fresh fuel into the tank to verify you aren't just on empty. This is also accompanied by the vehicle jerking and hesitating while driving and then suddenly stalling as it runs out of fuel.

Unfortunately there is no factory fuel test port on these vehicles, you must buy a sandwich adapter for the passenger side fuel damper to install one if you want to test for fuel pressure (listening for the pump to turn on with the key on ON isn't an accurate way to measure for ACTUAL fuel). I went with the one from Z1 motorsports because it was cheap and had great reviews.
https://www.z1motorsports.com/z1-pro...rt-p-9160.html

To test for spark is very simple, first pull the fuel pump relay in the IPDM and crank the motor a few times to relieve fuel pressure to prevent accidental firing with a spark plug removed. Next remove a single coil pack and spark plug, put the spark plug back into the coil pack, wear leather gloves, hold the coil pack by the TOP of it where the electrical connector plugs in and place the ground strap of the spark plug (the hook part at the end) up near the aluminum intake manifold about 1/4" away while someone else cranks the engine. You should see spark, if you do NOT see spark then you most likely have a CKP or CMP sensor that failed.

Only use OEM or Hitachi (the OEM supplier) brand CKP and CMP sensors, other brand aftermarket sensors are VERY notorious for not working.

 

You probably have an EVAP problem or a leaking injector, when it won't start try turning the key to the ON position, then back off about a half dozen times. Leave the key in the ON position for a couple seconds each time, if it does start consistently with this method your EVAP canister is probably saturated. If it still won't start, run the engine and get it to the point where you cannot restart the engine and then quickly pull all the spark plugs and see if they're wet looking. If they are then you have leaking injectors.

If those two things don't work you might have a CKP or CMP sensor that's only malfunctioning when hot, I would suspect the CKP one and replace it first.

If you smell gas while driving you're leaking fuel and definitely need to find the problem, look for the wet spot it shouldn't be too hard to find.

 

Try adding like 2 gallons of gas to the tank the senders become faulty and give out misreadings of fuel level.
Try adding a starting fluid and see if it fires up to eliminate spark, possibly cam/crank, etc... then you'd be left with a fuel delivery problem
I'd put those other parts back on first too. You're introducing too many variables at once and new parts are sometimes defective as well.

 

What cleric said. Something not working after has been running is usually due to heat causing an issue. It could be a fuel injector, fuel pump, and/or the sensors he mentioned.

 

Car cranks but no start read all forums an found out ecu might be the culprit bought used ecu an still same thing can someone help please

 

You cannot just plug in another ECM and have it work. Needs to be programmed at the dealership for the vehicle.

I suggest you tow the vehicle to Nissan for a diagnostic.