Noise when accellerating

[mylesw]

Hi there. I'm new to the forums, but thought this might be the best place to ask about this. I have a 1997 I-30 Infiniti that I love. The car has about 95,000 miles on it, and is in relatively good condition. It's been pretty much trouble free ever since I bought it.

About 2 years ago, I noticed a noise when I put my foot down to accellerate. I normally play my stereo loud in the car, so I don't hear it much. But over the past 6 months, its getting louder. Not still too bad, but I would like to get the problem resolved as I have to some longer road trips coming up.

The noise only ever occurs when I press the accellerator pedal. There is no sign of it when the car is moving without me pressing the accellerator. The noise appears to be coming from the engine (as best I can tell) and kinda sounds like it has something to do with the fueling system. I have no leaks at all, and I don't seem to be using any more fuel that normal. It also doesn't appear to be happening within certain speed levels. In other words, if I am traveling at 30mph or at 80mph, the noise is no different. Again, I never hear any noise when I'm not pressing down on the accellerator pedal.

The noise sounds almost like an electrical whine, and not a mechanical sound if that makes any sense.

Does anyone have any ideas on what could be causing this? I don't want to take it into a repair shop without some idea of what might be behind this as I'm not exactly sure I trust repair shops to give me an honest opinion.

Any thoughts? And thanks in advance for any advice.

Regards,Myles

[Beancooker]

Have you replaced the serpentine belt? That could be the problem. Also, is it a whine, or maybe like a whistling sound? Is there any certain RPM that it does this at, or is it through the entire range of RPM's?

[mylesw]

I haven't replaced the serpentine belt. I have routinely put the car through its normal maintenance pattern per the Nissan recommendations, so I'm not sure at what point that normally comes up in a car like mine.

The noise is more like a whistling sound than a whine sound. Of course I suspected that much of this could be coming through my audio head unit, but with the audio turned off it still sounds like an electrical whine than something mechnical. But its very hard to explain. What I can do is to record it and put a WAV file up here something so people could hear it. That might a good idea, and I'll go ahead and do this.

As for RPMs it doesn't seem to make much difference at either what RPMs or speed the car is traveling at once the car reaches about 2,000 rpm. I do notice that it takes a couple of minutes before I hear it when I start the car cold. But after the car has warmed up, it becomes audible. The more I drive the car, the louder it seems to be.

Myles

Modified by mylesw at 12:30 PM 3/4/2007
Modified by mylesw at 12:31 PM 3/4/2007

[mylesw]

OK, I have recorded the noise. Thank god I'm an audio engineer...

Take a listen to this MP3 file. I've amplified the section when the noise comes in. I can best describe it as a 'whistling sound' that accompanies accelleration. Hopefully you will be able to hear it ok.

Also I noticed that it doesn't appear to occur when the engine is running lower than 2,000 rpm if that is of any help.

http://files.techsol.org/other/i30carnoise.mp3

Myles
Modified by mylesw at 1:29 PM 3/4/2007

[Beancooker]

I'm like 99% sure it's your intake plenum.

Check out THIS THREAD

[mylesw]

That's really interesting. It does seem that I have a lot in common with all others who posted on that.

So is this something that can be fixed? What would you suggest to remove the noise?

Myles