Hey Guys,

Apologies in advance if this is not in the right sub forum.

I've recently started to hear an odd sound which seems to be coming from the engine. It started about a week ago. My wife said it sounds like gravel. I think that's an extreme way of putting it. To me it sounds a little like knocking and a little like playing cards flapping against a bicycle wheel's spokes.

It happens when the car is "cold". And I really only hear it when I throttle. But once I've driven for a good 10 minutes, nada.

The G has about 39k miles on it and its about 4.75 years old.

Any suggestions on what this might be?

Has anyone experienced this before?

 

Could it be transmission? 6mt or 5at car? Does it do it in neutral too or just when you're starting to move?

 

Sorry, Don't know why I left out those points.

Its a 6mt. No I don't hear it in neutral. And its not just when starting to move either. Probably around 20 to 30 miles per hour. And then I give it some good gas. Its like a flapping sounds. And only when the car is "cold". I don't hear it after about a good 15 to 20 mins of operation.

 

How loud is it? Can you hear it when the radio is on or does it have to be off to hear it?

Sorry to say but if you're not super specific, its hard to tell. Theres a lot of noises that come out of this car. Sometimes its something stupid and minor like loose interior parts. Hell, my keyhole is loose.

 

I can hear it over the radio at normal radio levels. The more I think about it the more it sounds like an engine knock. It really only happens when I give the car gas. If I'm at cruising speeds I don't really hear it. Also when accelerating I hear it, but not when shifting (as I'm not throttling then), so I would tend to believe its not transmission related. But again, I'm not the expert.

Are there any problems with this engine at around 40k mile? Its recently gotten slightly colder here. Not sure if that's contributing.

Thanks for all the help guys, and if I'm not giving the proper information about the noise/experience, please help me drill down with the right questions.

 

no idea what the cause is, but im pretty sure i have the same problem.....with mine it ONLY happens if i turn on the car and give it some gas, it'll do it once then never do it again until i park, go to class or wherever then start it up again...mine is an 04 AT

ohh and mine only has 26k miles

 

Ok, does it sound like tiny pebbles are jumping around in a sheet metal box? That could be pinging or knock.

 

Thanks Evo, yeah you could that this is the kind of noise its making.

Also saw this guys post here recently. My conditions sounds a lot like his.

https://g35driver.com/forums/engine-drivetrain-forced-induction/190639-strange-rattling-sound-throttle.html

 

detonation...something wrong with your fuel mixture...I always put super 93+ octane in the car since new never had problems....could ruin your motor if not checked out...

 

you still got some time on your powertrain warranty

 

You might have your dealer tell you that this is normal and they won't do anything about it. There are a few people on the board that have had dealers tell them this. Do searches for pinging, knock, and detonation and you may come up with those threads.

Is your engine modified? Any reflashes or timing adjusted?

 

Sadly its bone stock.

Thanks guys. Unless the feul vendors are switching out 93 with the lower grade stuff then the only gas that goes in the G is 93.

Guess I might take it to the dealer and see what they say. Thanks for all the advice. Oh and btw, anyone know how long the powertrain warranty lasts? (too lazy to look it up right now).

 

Let us know what the dealer says.

For myself to know and for the OP also, what are other ways to read A/F besides on a dyno? I'm no expert either, but I recall something about running lean could cause detonation.

 

I have the same sound but it only show up when idle, i discovered later it was the Intake System Rattle and it only happens when the car is stopped, while moving its normal no sound at all, fixed the intake issue again the same sound showed up and i don`t think its related to the intake system this time, the sound can be heared very well on the passenger side, just put ur ear near the right fender and u can hear a metal shaking, oh BTW i got A/F Ratio gauge too it flickers between 14.5-15.0 at idle.