Hi guys, I am posting after about a week of studying the forums here and not finding a single person having the same problem. Here's the situation. We have a 2006 G35 with the revup engine. We were experiencing overheating issues and after it sat for a while (over a year) we finally replaced the thermostat. The car was running and we were doing the coolant bleed. During this the car was idling better than it has in quite a while it was not overheating and we thought we had found our hallelujah! well mid coolant bleed the car backfired, revved itself down and then shut off and has not turned back on since.

List of things we have tried/done:
checked all connections from replacing thermostat (we did and two mechanics checked behind us)
added fuel
changed the spark plugs
replaced the VVT solenoid (P0075)
new battery (that had to be charged because of trying to start it so many times)
cleaned fuel pump and reset it
cleaned off 02 sensors
checked all connections
replaced the crankshaft sensor

we ran the code reader we got codes P0075 and P0462.
Code p0075 will not clear no matter what we do. we have checked the connections and replaced the solenoid in bank 1 (passenger side) this has not changed the reading of the code. it is still present.
Code P0462 clears when we clear it and hasnt come back after cleaning the fuel pump.

we have tried starting fluid in the intake. we have tried push starting it. we tried the key thing and that hasnt seemed to make a difference either. We used the exact same key that it was running off of prior.
We can hear the fuel pump priming. we can tell the engine is getting fuel. its getting air. and aside from replacing the coil packs just to see if it works. we checked fuses. replaced some of them. I really dont want to just throw any more parts at this car. What should we be looking for? or checking?

we are lost. Please help!!

 

Check for compression. I just went through pretty much the same thing you did. Checked compression and there was none. Timing chain took a dump on me and had to tow it home some 700 miles away. Jump forward to now, looking for a JDM to purchase and install. Good luck to you.

 

If you have fuel, spark, and air then the engine should run. U have physically checked to see if the injectors are spraying? U have checked to see if the spark plugs are firing?

If u have those and it still wont start, then its either timing or really bad compression. Since it died instantly, I would rule out bad compression.