2005 g35 vq 3.5, i installed new head gaskets, all new gaskets and a water pump,spark plugs, car starts up and sounds rough and check engine light flashes, gives 3 codes
P0300 random misfire
P0462 Fuel level sensor A circuit low input
P0021 intake camshaft position timing-over advanced bank 2
if my timing chain is off a little will that be the reason for the random misfire? im trying to see if they are related, im pretty sure im going to have to take it back apart and check the chain marks, i know the bottom key was off to the right of the marking, but the top cams seemed to line up.

 

Those indicators on the chain to the sprockets will line up EXACTLY if it's installed right, you will usually have to make a degree or two adjustment on cams/crank to get everything lined up perfectly but it MUST line up PERFECTLY as shown in this picture.






However you should check to make sure you didn't mix up the coil pack harness wires first.

Coil1 - yellow/red stripe
Coil3 - Blue/red strip
Coil5 - Purple/white stripe

Coil2 - Green-red strip
Coil4 - Grey
Coil5 - Grey/red stripe

Every coil the other wire is white/blue stripe so ignore that one and just pay attention to the other wire, make sure they're all plugged into the correct cylinder it's VERY easy to get two of them mixed up.

The fuel level sensor low input is unrelated, that's just the level switch in the pump starting to fail, probably just needs to be cleaned. You can take the pump out and where the level arm makes contact on the board use a #2 pencil and scrub away the corrosion. Use the side of the pencil lead and those contacts will clean up perfectly in seconds. Some folks use a q-tip and rubbing alcohol, some use a very fine sandpaper, I've always had the best luck using a #2 pencil with stuff like that. Just wipe the graphite off when you're done.

There are TWO level switches, one on each half of the tank, one side has the entire pump assembly, the other side has just a level switch, clean them both.

Here's a pic of the fuel level switch, I circled the park that needs to be cleaned, if you look there's a "darker colored stripe" across those metal contact strips, that's the corrosion that needs to be removed, that's where the arm makes contact. If any of those little metal arms are worn through then the entire unit needs to be replaced. I personally don't like using alcohol because it doesn't get rid of the corrosion (I mean it's submerged in gasoline and THAT doesn't remove the corrosion so why would alcohol...), I don't like sandpaper because you can remove a lot of metal quickly plus it leaves the surface too rough. A #2 pencil is just the right blend of physically scrubbing the contact without causing damage, I've used it on ALL manner of electronic contact points over 3 decades from old NES cartridges to dishwashers to fuel level switches.

 

Well G35DRIVER glitched out and the servers went down for a few minutes so I'll edit my previous post and fix the stuff that didn't get put in correctly...

 

thank you for the reply, i am taring it back down right now, im at the cam sprockets, when i put on new head gaskets i didnt go by the markings so i am now. heading back out to unbolt the sprocket.

 

Just make sure you start at top dead center cylinder 1, the dot on the sprockets will end up in the middle of the colored link on the chains.

 

yeap after the 3rd time breaking this engine down, this time all three chains are lined up exactly on every mark, tomorrow i will put it all back together and see.

 

Verify the wire color on those coil packs, it's VERY easy to get them mixed up.

 

im still putting back together right now, i noticed i put the injector cable in back wards, would that also cause the random misfire, ty