I have a 2000 4Runner and I have a strange noise coming from the rear of the car.
It only happens between 5 and 30 mph, it is a high pitched noise (a chirp) that gets louder as I put slight pressure on the gas pedal. If I accelerate faster, I do not hear it. And at highway speeds (over 50) I can not hear it.
Sometimes when the car is warmed up and I have been driving for a while the noise is not there. Mostly when it is cold and I pull out of my driveway in the morning. (the first 10 miles)
It is not a brake squeel, as I know the low pad alarm noise is different.

I wonder if an exhaust or a catalytic converter leak could make this noise. (It is also different from a wind noise )
It does not happen when I am not moving, only driving with slight pressure on the accelerator. (also when I let off) a little.

I hope that some of you out there have experienced this, or know about this problem?

Thanks much for this website, it's great.

Nick )