Noise on deceleration, and one hard shift

[andante147]

I just bought an '03 GTP with 125K. I plan to get more complete service records from a dealer in another suburb. In the mean time, I'm not sure if these symptoms are related ..

NOISE -
I haven't been at highway speeds yet for any length of time, but in all of my suburban driving if I've accelerated to 40 or 50 mph, as soon as I let off the gas there's a definite noise...it's a "wooooo" sound - (pardon my musician's observation, but it's about a G above middle C, and varies a bit with speed)... or you could compare it to the higher sound semi tires make on an interstate, or a bit like a shop vac running.

It's totally consistent, and stops the second I tap the accelerator.

ABS/TC Lights? - I wondered if this was a bad wheel hub/hubs because these lights are on - but suspect not because there's no noise during acceleration.

Supercharger? - I assume it's not the supercharger functioning normally - why would it make sound when I'm not touching the gas?

Tires? - it has fairly new tires, but the noise is so specific to the application of the gas pedal that it seems unlikely.

So I wondered about a transmission issue... something like a torque converter hanging up in some way?

HARD SHIFT - I had just ONE very noticeable hard downshift in traffic yesterday - it just jerked from 2 to 1 (I think) Only once so far.

I've been reading about trans coolers and shift kits, and might install as preventive maintenance, but I'm also curious if this noise is trans related.

Thanks - sorry so long...

[andante147]

Forget the noise, on today's drive to work I had one hard shift into 1st and one into reverse. So - crap - my 5-day old purchase has a transmission problem. Plus the ABS and Trac Ctrl lights are on. (I really didn't *want* an ACCORD or CAMRY!!)

So - I'll try to focus on one thing at a time ...

Is there any value in getting a flush/fluid change at this point before I take it for repairs to see if it gets better?

What's the cheapest and most accurate way to address trans problems without just jumping into a rebuild? Or is a rebuild always the best route?

Thanks!

[grandprix85]

If I was in your situation I would get the car scanned for any transmission codes. If there is any transmission codes then I would see what the transmission shop says about them

[Lawngoose]

Your wheel hub bearings are bad, mine makes that same woooo noise.. and they are tied into your ABS system.

Here is a link to a how-to ... Wheel Bearing Hub Assembly Replacement Guide - General Motors Pontiac Grand Prix GTP - Pictures & Instructions

I shall be replacing mine too.

[andante147]

A very belated thanks! I'm not sure if I'll do the noisy side and wait until I have trouble with the other, but we'll see.

I wonder if any brand at Rock Auto is Korean? The National and Timken are cheaper than what I can find locally. Both have 1 yr warranty... any idea on quality on either?

RockAuto Parts Catalog

Thanks