Tapping from under dash @ 2000rpm+

[zinger_usa]

Hello!

Just curious if anyone else has experienced or heard of this and if so what the solution is. Sometimes I get this tapping noise (sounds like a fingernail tapping on the bottom of a full can of food) that comes from somewhere under the center part of the dashboard. It seems closer to the firewall than the front of the center console. It starts at about 2000 rpm's and continues up thru at least 4000 rpm's. It speed increases with the rpm's. It also only manifests itself when I am actually on the gas, so if i am at 4000 rpm's and let off the noise stops instantly. It will do this whether I am sitting idle or driving, and doesn't matter what gear I am in. I have never been in behind that part of the dash, most I have done is replaced the stock radio with an aftermarket one. I have also had the instrument cluster out a couple times, and this involved dropping the steering column. Today and a few days ago it was very prominent and the weather was around 35-40 degrees F. Any insight you can give me on this would be most appreciated. Thanks!

Jared (Dover NH)

1991 240SX HatchbackAutomatic Transmissionapprox 200,000 miles

[NISTECH]

it sounds to me like something connected to the engine is hitting the firewall and causeing a vibration at those specific rpms. Check to see if any brakets or any thing are rubbing against the firewall also check any of the hoses like the brake booster hose or brake lines. try shifting things up there and rechecking till you isolate it to the source of the noise.