Since I had my motor replaced, I've been focused on a tapping noise when accelerating. It kind of sounds like very light pinging/knock but faster... yes I use 93 octane. There is no performance hit so I don't think it's knock... it actually pulls quite nicely compared to my old engine. I'm thinking it is valve noise but was wondering if anyone else notices this. Is this just the valves opening and closing amplified through our "sound tube?" I heard it on my first engine as well but wanted to see if some of you would turn the radio down and check for me. Thanks!

 

I noticed this as well...so much so iv been thinking about bringing the car in to get checked out for the first stages of rod knock...is rod knock a common problem with this car? It seems that i have seen more threads about it than id like to see.

 

I went ahead and gave this a looksee (or a hear-see?). I didn't notice any tapping sounds when accelerating at low speed or at cruising speeds, nor at accelerations past 5k rpm in "manual" mode.

I'm running 91 octane, but did put a 5oz bottle of Lucas injector cleaner in the tank about two fills ago.

What I do notice is a abnormally high idle rpms upon initial startup in the mornings or when returning to my car at the end of the day after work (at least 8-9 hours not driving), usually around 1400-1700 rpm. After a while, it will work itself to a normal 600-700rpm. I'm not sure if this is normal, if I noticed this only recently, or if it was the effect of installing that powered sub (which is likely). Either way, it's not so much of a bother I suppose I'll probably investigate more thoroughly when I start installing my new header unit.

 

As far as the high idle on start up, it is normal. All my Nissans from cars to trucks have done it. And here is the list of what I or somebody in my family has had and all of them do it.

1990 300ZX (Mine)

1989 Maxima (Mine)
2003 Maxima (Mine)
2007 Maxima (Mine)
2012 Maxima (Mine)

2004 Altima (parents)
2008 Altima (parents)

1999.5 Pathfinder (Mine)
2004 Xterra (sister-in-law)

 

I figured it was normal but got a bit paranoid after installing that sub. Thanks, ajmbeatle!

 

I do not hear any kind of tapping during acceleration, just the normal "growl". Perhaps you could record the sound?

 

I cant hear the tapping in the car while driving...but if i open the hood and push down the gass while in park i can hear it....i did take a video of it but he tapping noise really wasnt audiable in it...im guessing cause itbwas taken on a tablet and not a camera

It could be really loud injectors but i dont think it is. i was rocking 550cc injectors on one of my turbo motors and didnt hear tapping like this...these maxima injectors cant be any more then 350cc so they wouldnt be any louder....better not be rod knock or im gonna be pissed

 

Have the dealer check for #1 main bearing NTB12-071

http://x.nissanhelp.com/forums/Knowledgebase.html?catid=627

You can also read my thread dealing with my engine issues and pictures...

engine knock/head gaskets w/pics
http://forums.maxima.org/7th-generat...ts-w-pics.html

My engine knock was during warm idle (lower oil pressure) and was b/c of a improperly sized main bearing.

Thanks for checking for me! My noise is upon accelerating and is very subtle. I'm going to try 5W-40 and see if it helps any.

Get your engine checked for the main bearing issue and don't accept "It's a normal engine sound for this car."

 

I also agree that your idle is normal. I routinely have it start at about 1700 rpms and slowly go down. Seems a little high, but it's always done it... both motors.