Another "Weird Noise" Thread
 

I apologize in advance if this has been answered already but my search journey came back with nothing.

Anyway,
Symptoms:

1. Sounds kind of like a high-pitched coffee grinder
2. Occurs around 30mph when accelerating
3. Goes away if I let off the gas but will come back when I start accelerating again. Also goes away once I speed up past ~32mph
4. Occurs when going in reverse (obviously not at 30mph, just reverse in general)

During my drive home from work I'm gonna see if the sound occurs when the car's in a specific gear or if it's just throughout. I'll also try taking a video of the sound and posting it up here.

But until then, any initial thoughts?

Any vibrations felt through the wheel or seat?

Sounds like pinging to me (autoignition). What grade of fuel are you using? Although my 2010 hasnt ever done this when using 87 octane, anything is possible.

You havent had spark plugs replaced anytime recently have you?

Maybe im confused...coffee grinder as in the beans rattling around or the motor turning?

If it sounds like an electric motor turning, it is likely radiator fans, although they probably have something wrong if you can hear them at 30mph.

No vibrations

Always 93 octane. Spark plugs haven't been replaced. Coffee grinder as in the beans rattling around.

Grab a video?

Yup....thinking that may help to see what the noise may be.

So...in D...hold brake and hit the accel pedal briefly. See if you hear the sound. As in...ease into accel pedal and go to floor and see if you hear the noise. Dont worry...it is an approved test by nissan to check the torque converter stall speed. You wont hurt the car but shouldnt hold it longer than 5 seconds.

Loading the engine will tell you if it is pinging and its much easier to hear if the car isn't moving.

Yup, tried this out and I hear the sound. Didn't even have to press the accelerator to the floor. I got about a quarter of the way and the sound occurred.

I will go out to the parking lot during my break to see if I can get a quick video.

heat shield?

I tried to take a video from inside the car but you can't hear anything. So I took the video from outside the car.

Here's the video: https://sendvid.com/ln00xajp

I apologize for this wind for the first 20 seconds of the video. You can really hear the sound after the wind dies down though.

I will rule out my heat shield seems a little low for the clinking of a heat shield, Almost sound exhaust related. What is everyone else thinkin?

When I was searching the forums couple weeks back I did come across a thread where someone mentioned the heat shield was making a rattling noise. I didn't think that was related to the noise I'm having while accelerating.

Where is the heat shield and can that actually cause a rattling noise from acceleration?

Just did a search for "heat shield noise" and found this thread

Weird grinding noise on cold start

The noise is pretty identical. Is it safe to assume I'm having the same problem?

does it do it in N(eutral) with the parking break on? if so and you aren't dropped on eibachs then you could grab some heat resistant gloves and from a cold start see if the noise rattles and feel around. try all the heat shields and check if one stops the noise with holding it down. That would be my next step.

Does not do it in Neutral or Park but does it in Reverse and Drive. I realized that the sound is not associated with the speed like I originally stated in the first post. Rather it's associated with the RPMs. The sound only occurs between 1300-1500 RPMs, regardless of the speed at which I'm driving (or not driving in the case of the test CorollaULEV suggested.)

I tried out a couple different things to come to this conclusion. With all of these I slowly pressed on the gas pedal while idling and steadily increased RPMs.

• With the car in P ---> nothing
• With the car in R and my foot on the brake ---> sound started at about 1300 RPMs and stopped after I went past 1500 RPMs
• With the car in N ---> nothing
• With the car in D and my foot on the brake ---> sound started at about 1300 RPMs and stopped after I went past 1500 RPMs

I then took the car for a drive and accelerated very gradually, keeping my RPMs under 2000. I hit 20mph at 1300 RPMs where the sound started and accelerated to about 45mph. I reached 40mph at 1500 RPMs before the sound finally stopped.

Not sure if any of this means anything but I thought it may help. This weekend I'll try going underneath the car and locating the sound. Where is the heat shield supposed to be?

Just went underneath the car this afternoon and found that the 2 out of the 4 heat shield flanges have come loose and that is what's causing the noise. I also searched around more and found this thread

Broken Front Exhaust Rust Heat Shield Flange

I see that there's a service bulletin on this issue which says to use hose clamps to fix the issue. I've also read that a lot of people are just removing these heat shields completely. I'm leaning towards the latter myself. How would I go about removing them? Do I need to drop the exhaust and take off parts to slide these off? Can I just use a dremmel and cut the flanges?

Drexel, big pliers, carefully with a saw.
The dealership removed mine when I complained about the rattle.

This will be getting bookmarked asap as it is great info! This is the type of thing that would drive me up the wall until i found it!

it happens on bimmers all the time, i remember countless times hearing the same complaint and telling the owners, gimme five minutes lol

they make a much more rattling, bass tone than what op described tho

Yea thats why I ruled mine out at first, not to mention they usually rattle in N as well, not as much but should still rattle.

Nice! Glad to know that you found what the issue was.

yep, same rpm range that it would happen also