Okay I'm going to try and explain this to the best of my ability ,i start the car from cold start and beging to drive slowly until I hit Operating temperature. During this process a noise comes from under the car when I hit about 2,000 - 2500 RPMs and stops at 3,000.... It kind of sounds like a raspy kind of noise kinda like a ricers exhaust sound lol... Best way I can explain it .... Once I drive and hit operating temperature it stops and goes away
I don't know what this could be , help please

 

Possibly a crack or something in a piece of exhaust tubing that closes up when the exhaust gets hot. I may have just made that up though.

 

Exhaust is noisy when cold for all cars. There may be a small leak in the pipe so when the engine warms up the noise is too little to be heard inside the car. But I would not worry about it now. When you hear a constant noise all the time, that's when to take it to the shop because it's much easier to troubleshoot when you hear the noise ALL THE TIME.

 

I thnk its ur flex pipe, I had the same issue

 

Yeah it's so annoying , and if I'm just steady driving like 2100 RPMs , it just holds that note and kinda sounds like a grinding (goes away once it hits OT)

 

does it make the noise when your in park or just while driving?

 

no not in park, drive only, only when i hit about 2,000rpms and goes away at 3,000 rpms and goes away when the car hits operating temp. and driving.

 

I got the opposite problem as you. When im in park i hear an annoying rattle but when i rev it a little no rattle and no rattle when im driving.

 

Something could be loose under the car and vibrates when it is colder and/or at low revs. When the engine gets warm the gap that is causing vibration may close. Maybe crawl around under the car and wiggle some exhaust pieces, heat shields, etc. when they are cold and see if you can detect anything that could be loose.

 

If it's only happening in drive it could be transmission related. I'm not an expert but I believe transmission fluid expands slightly when it's heated up so you might be a little low and once you get up to operating temperature it expands enough to allow your transmission to work properly. 2k-3k RPM seems about right for the transmission to attempt a shift under normal acceleration and it could be slipping slightly because of a lack of fluid pressure.

These are all guesses though so hopefully somebody smarter can chime in.

I would check my fluid level regardless though since if that is the problem it could cause serious damage over time

 

This sounds like my problem, and it is the heat shield for the catalytic converter. At 1300RPM, and also 2400-2600RPM, my car makes a noise like the muffler is going bad. I had a shop do the large clamp thing around the shield (driver side for me) and it helped but did not completely cure. Some spot welds came loose on the driver side cat heat shield - I could move it some from under the car. The passenger side one does not budge if I try to move it side-to-side.

If that's your problem I don't know if there's a real fix.

This noise only happens under load - not in park at the same RPMs. If you are going up a slight incline and you happen to have the gas such that the RPM range is what I described above, that is when you really notice it.

Shop I had it into says people are more and more bringing in G35's complaining about this issue.

Edit: oh, yours goes away when at operating temp. Must be something different then.

 

Wheel wells, skirts, anything that has a round plastic puch rivet.

 

Wheel wells, skirts, anything that has a round plastic push rivet.

 

If it happens only once after you start your car and drive my guess is it's the ABS self test. Does the noise only happen once for a short time and then disappear? I describe the sound as driving over a grate and if you have your foot on the brake pedal when the noise happens you will feel it vibrating. First time it happened to me I freaked the F out thinking my car was about to explode.

 

This sounds like the same issue I am having. Could you just take the heat shield off?