Hey sorry i dont mean to crash this post but i have a 5AT and I dunno if its a engine knock but at idle i hear the car sputter a little but the RPM doesn dip. The sound is from the Exhaust tho and it sounds like trapped air that escapes? When i rev in P you can hear the popping when the rpms descend below 1k? Is this the same thing as being described in this thread?

 

you guys are worried about knock in a naturally aspirated car that makes appropriate hp for it's size? wow.

 

Make sure the oil is clean and full, and that you have the correct gas.
Run a fuel injector cleaner thru once to see if it cures your issues.
C.

 

err.. if it is indeed "knock" that is being referred to.. and not just a knocking sound.. i would be worried about it in any car of any type of any hp of any size.. detonation can only be bad.

 

i am very aware that detonation is bad. i just don't think that a 3.5l pushing 280hp is as prone to detonation as some of the smaller more high strung engines out there.

 

okay, so youre saying that the knocking sound they are hearing probably isn't detonation. that's fair.

 

I have a 5AT and I get the same sound that was described- like a pop coming from the exhaust once in a while. I can also feel it slightly through my seat when this happens. I've asked about it before and people have said it's normal and everyone has experienced it with VQ35's. As for the idle, mine is very low as well, stays around 600.

 

i seem to have something like that happen every now and then... not sure what i should do to help the car (if anything)? nothing i can do about the fuel, but ill try to double check the oil level......

 

correct. no engine should knock (detonate) at idle. if an engine is going to knock, it's going to do it when it's under a high load, definitely not idle.

i'd look at a slightly low idle or maybe just valvetrain noise.

wrx's make some god awful noises at idle in cold climates, and they're all perfectly normal.

 

ive been having a lot of engine knocking as well.. sorry to bring up the thread but i wanted to know if u guys had any new ideas.. it is just like what other ppl are saying.. at idle my car makes some weird puttering sounds.. and my RPM does go up and down tho.. like a little bit.. it is loud enough to be noticable from the outside. My car also idles at a very low rpm.. it is at like 1 line before the very last line.. like 100 or so RPM? Is there anything serious I should be considering? Its been doing this for a very long time but nothing bad has happened yet.. aside from looking kinda stupid when the cars idling at night..

 

I get the impression that people are talking about all sorts of different noises here.

1. Engine knock: not normal
2. "popping" sound from the exhaust after revving: normal (IMHO, sounds cool)

 

Thats it! Its a popping sound on my car. I think its normal.

 

Damn I was behind my car the other day and heard this strange sputtering sound..... then I realized, my car has exhaust pipes....

All cars "sputter" a little at idle, with an aftermarket exhaust, such as the Injen I have, the car sounds like a sputtering machine. Then it sounds good when you get on it, but Knocking at idle = someone massively screwed with your timing. My boys Z28 blew a knock sensor out about 3 months ago, when he put it back in, the reason was... bad knock... at 4800 RPMS. Retune, and bingo alls good again (hopefully thus far). He also is quite considerably above the "stock" hp of a z28, but thats another story. If your hearing true engine knock at any less than half throttle and about 1/3-1/2 the way up your tach, then you need to get to infiniti for a new engine pronto.