My g37 has been having problems for about the last 2 months. I was getting random misfire codes and also fuel smell after driving the car.

so I talked to my tuner and we started replacing small things first. So far I’ve replaced my fuel pump, cleaned injectors, spark plugs, MAP sensor, also added a ground kit thinking it was electrical at first, I cleaned throttle bodies, tested maf sensors, inspected intakes for leaks, and also did a tune.

My tuner flushed my fuel lines and rails and said it almost looked like there was silicon inside the lines. That helped ALOT but still have a bit of stuttering during acceleration and lower RPMs. Initially when I had the problem my car made 218whp which is horrible but after fixing those things it made 260whp.

any ideas what it could be? Also plan on replacing my VTC gaskets on both sides of the timing cover, spark plug tube seals, upper to lower manifold gasket and valve cover gaskets.

any ideas would be greatly appreciated.

 

I am having a similar problem, although not as in depth as yours. In severity of your problem, I couldn't tell much further as you've changed what I would have done. The only other part I would do next as part of the whole area of fuel / ignition, would be coilpacks.

The issue for mine, if you don't mind me exchanging ideas, is my car in neutral and park will sputter and lean out randomly. My fix will be to soon get new plugs and injectors. Along with this issue, my car will also make a grinding noise whenever it shutsoff. Does not matter when, any ideas??

 

hey! Sorry to hear you’re having similar issues. So actually, I replaced my valve cover gaskets and spark plug tube seals because there was oil on the threads of each spark plug. Let the car sit for 2 days and the last 3 days it’s been driving perfectly. Also going to get the VTC cover gaskets replaced because the driver side is leaking. But I would definitely clean the injectors and even the fuel lines and rails. You should also replace the valve cover gaskets and spark plug seals. Fairly easy to do with a decent amount of knowledge. Definitely watch some YouTube videos on it. Let me know if that resolves your issue!!