Thread: Slight thump noise on braking & acceleration near firewall

Recently, my '97 Grand Prix Le with 144K miles started making a very slight thumping/knocking sound in the engine compartment near the driver's side firewall. The noise occurred occasionally when braking and accelerating. Yesterday, the brake light came on and stayed on until turning the car off for an hour and then restarting. I checked the brake fluid level and it was fine. Today, I drove to the store and the car ran as well as ever, but when I came out and started the car, the engine wouldn't idle enough to put it in gear without stalling. After turning off the engine and trying to restart, it just turned over without starting for quite some time. On a subsequent retry, the engine fired up and ran like new. This is the first problem I have had with this car since buying it new. It has been a great car and the reason I have kept it this long.

I wanted to run this problem past my fellow Grand Prix owners to see if anyone has experienced this problem or if anyone has any ideas which might point me in the right direction for fixing it. Could these symptoms be related or is the car just tired and on its last legs. Any help you can offer will be very much appreciated. Thank you in advance.

Check the condition of the trans. and motor mounts. If you see any fluid leaking from the mount it's done and needs to be changed.

Maybe try cleaning the MAF with approved MAF cleaner (don't use brake or carb cleaner on it). Just spray the tiny wires inside the MAF and let it dry. Don't scrub/touch them with anything or they will likely break and then you're out $150 for a new MAF.

At 144K I see no reason why it would be on its last legs. Heck, my 00 GPGT has over 200K on the motor and 300K on the body and still looks/runs good.

For the brake light coming on check your emergency brake. Often if it gets pushed down a bit or the sensor gets misaligned it will light up the light.

Thanks for the reply and your suggestions. Since posting my request for help, the car has run like new. I did check the motor and trans mounts and they are in good shape. Must have been gremlims or my car reminding me who's boss. Anyway, thanks again.