if its not that, its carbon built up. New coils, plugs, clean the pistions with some high-quality cleaner shit ( NN to be conservative ) , injector cleaner, 94 octance. romp around for a bit

this is always a good idea also

Only way to get 94 octane is to throw in an octane booster? that im assuming is fine?

it has nkg plat plugs, very new, i'll recheck the coils when i take off the intake. and i'll clean the pistions when i check the plugs and coils.

and i've sea foamed the car twice, it's very clean, but imma try that terra cleaner tht you suggested, i've heard wonders about it.

Gl

Do a follow up post also

Yeah i'll post some pics and stuff when i'm done what i'm doing.

as for now,

Current Sunday to do List:

Check Plugs/Coils/Pistons
Check Fuel Dampers (via stethoscope)
Check Engine (via stethoscope)
Check Intake Manifold heat shield.
(All fails, new vid with gf holding noise and me underneath car)


This post was edited by Bl00dy on May 31 2013 12:52pm

ive also heard good things about this bg44k shit but i dont have any personal experience with it.

http://www.bgprod.com/products/fuelair.html

Doesn't sound like motor noise at all to me.

Sounds like a loose heat shield, or exhaust hanger, or something bolted to the motor vibrating, as Tears said.

I'd check the heat shield surrounding the catalytic converter. Those are usually the first to go.

it could also be that far back around your cat, i forgot they have heat shields also

i'm not totally familar with maxima's but like everyone else is saying check heat shield. Also might check motor mounts or idler pulley, although both of these are typically more noticable.

does it have an overhead cam? if so depending on the setup of the vehicle it might be time for a timing belt change there could be just enough slack in it that at certain rpms it is causing valve rattle.
also seen someone mention something about 17 degress with the timing.

there are several different things people are saying are issues, including fuel strainer in tank,mass airflow (MAF) sensor, knock sensor. seems its a few things maybe lol.

also seen this is a post:

Read page 9-4 of owner's manual. It says to expect pinging under loads for greatest fuel benefit..Nissan wouldn't make these things up. Other high compression engines like the viper, corvette, ferrari..just to name a few..also experience pinging under load. If your engine is ping free, it means that it's running rich.

is this ur gf's car the same one that had the battery cable issue or different one?

EDIT: also i see alot of people saying fuel. something to think about is alot of the newer gas nowadays seems to drop in octane quick so u might want to try a fuel booster to see if it helps any, also i wouldn't let it sit around with a full tank of gas in it if u normally do that. If i remeber to when I see my brother i'll ask him what he thinks. he is a mechanic.

ANOTHER EDIT: also have u tried it with the ac on and off to see if it still does it.

This post was edited by toadboy on Jun 1 2013 02:05am

It has a timing chain, when i rip the car apart, i'll see if the chain has anything to do with it, (not likely though) gfs new car, new battery, cables were fine.
Ac doesn't have an effect in the noise, on or off still rattles
Fuel seems least likely, but i'll try anything to stop this rattle.

MAF, would pop an ECU code 9 times outta 10, if MAF was bad you could also noticed a fuel/air ratio decline (leading towards power loss)
Knock sensor is a possibility.
Fuel strainer imo is a long shot.