Ok so this pass Sunday I went and did the usual I went and put gas in my car I put premium all the time on my g35. I came back home and parked it and didn’t drive it all day. Monday comes and as I was about to head to the gym my car suddenly starts then idles really low and then it stalls. I did some research and a lot of people who were having the same symptoms as me on the forums and YouTube videos said to just clean the throttle body carefully and the maf sensor. I did both of those things and did all the relearn procedures too. Didn’t work at all I then decided to replace the throttle body. I replaced it and did the relearn correctly and still nothing. So I decided to look into the fuel system. The fuel pump works and it is aftermarket btw. I also checked my fuel pressure and I checked it by disconnecting the line that goes into the fuel rail and I turned the key to the on position and fuel was coming out of the line. So with that being done I’m assuming that the fuel system is good also there is no leaks. I don’t know what else to do. Does anyone else have any advice for me or did anyone experience something like this before???

 

Start with the obvious, plug in an OBD2 scanner and check for hidden codes, pull and inspect the spark plugs.

 

Have you checked for stored codes? Just because you don't have a CEL doesn't mean there isn't a code. I'd check before throwing any more parts at it.

 

I Do not have a CEL I checked before anything. But I did have a code before all of this for a bad catalytic converter. I was thinking maybe the cat is too clogged up making the air ratio increase but then again I don’t think a bad cat would cause the car to act how it is. The car starts up idles low and stalls after. If it was a bad cat I believe that it would just run like garbage.

 

It could be the crankshaft/camshaft sensors, my car acted like that when they went bad.

 

My car had those problems as well but fixed them now.

when I went to hollow out my cats, my car ran like **** after, not throwing any codes until later it threw a P0011 or P0021. When I say ran like ****, I basically mean that the car had a low idle start, little power, slow and slow as Hell (SERIOUSLY, it was SLOW that it was embarrassing. During this time, it progressively got worse to the point that full throttle would literally be the only way for me to drive the speed limit and not even that helped…), the car would pop randomly like I had a tune.

One day while I was driving the car, I was pulling out of my house on a hot start then the car idled 200 rpm, so I drove like a damn snail back to my house where the car died out from the low idle, Couldn’t break 7-10 Mph and could barely start, later the problem would be troubleshooted towards it not being a solenoid or any oil problem but a CrankShaft Position Sensor. Not sure why it threw a code for something different other than the Real thing, it basically gave my car a protection tune to go slower so I don’t break the car. I never had a problem with these but while you are at it, I heard the CamShaft Position Sensor could also cause these problems (Source: Other forums). Very important note: USE HITACHI OR OEM!!! Our cars are picky when it comes to these. They’re also fairly easy to change, one (Crankshaft Position Sensor) is right beneath the transmission, literally 3-5 minutes to change or look at (From jacking up the car as that takes about 2 mins), it’s right beneath the bell housing of the transmission (So damn easy to get to). The Camshaft ones are a bit tricky and are right behind the top end of the engine.



Not mine but someone else’s taken off of a g35/g37 forum

Some suggest to take off the plenum so it could be way easier which I didn’t do because I’m lazy but it is sooo hard to reach back there.

Do a little troubleshooting around there though. The only time I’ve ever had those problems was when I had the worst case scenario which was my crankshaft position sensor telling me that my flexplate is screwed. But still check those sensors just in case as it could be a bad sensor.

I do suggest waiting for more suggestions as I also believe this might not fix your problem, there are other problems out there that also include your symptoms so just give it a few for others to chime in…