Hey guys! New here. I'm having the biggest issues with my G35. 03 G35 coupe,if that matters. I blew the 1st motor as it was junk anyways,and put in a new one with a timing chain kit,along with other things for future maintanance. Ever since the new motor,its been acting weird. It keeps giving me P0021 & P0011 for cam sensors. My uncle had a FX35 at his shop with a head gasket issue,so he gave me the 2 sensors to try on mine and it fixed the misfire issue for a few miles but now its back,and it keeps coming back. Its been like that for months,since febuary,i just clear the code and its fine but it comes back about 50 miles later with a random misfire code as well. The car now has the VDC and SLIP light on now,but i think thats from the clockspring since i moved it in and out during a steering shaft replacement. Anyways,i was driving it home today and the light came back on,and it sounds like driving normally it backfires as soon as i let off the gas at any speed or RPM. I'm not sure what to do anymore,i don't want to spend the money on cam sensors if its not what it is,if anyone can put some input i'd appreciate it!

 

did you undo the harnesses from the ignition coils at all in your engine work?

it is very easy to mix up the wires for cylinder 4 and cylinder 6 harnesses. Thats my only experience I can offer when it comes to misfires, since you said the cam sensors have already been replaced. check all wiring for damage too i guess, gl

 

Was this a junkyard motor you installed?? How many miles on it?
First off, check your oil. Its common for the DE's to throw those codes when oil level is low, as the VTC sprockets are apparently the first to starve from lubrication when the oil level is low.
P0011 and P0021 are related to the VVT, so if oil level is ok I'd clean/replace the VVT solenoids (top of cylinder head, near timing cover). I'd double check the timing too. Did you use OEM or aftermarket for the timing kit?

 

Maybe something with your timing chain, those tensioners/pressure points are prone to slipping, i would think it would cause a bigger problem though just a shot in the dark