Bowman97

I am a new mustang owner a'97 4.6l GT 5speed all stock. The exhaust has been cut off after the mufflers and that is apparently the only modification I am aware of (it's loud). When I get on it she starts rattling in the higher rpm. I run Chevron Supreme gas but that hasn't made a difference. Does anyone have the same challenge ? - Bowman97

mustnglvr

I would check your plugs

Darkcrime

Supreme? You need to run regular in that car. Stock stang takes 87.

Bowman97

Thanks for the answer! But wouldn't a higher octane remedy the pre-detonation?

Tapeuup

use name brand gas and not zippymart, cowboy etc. I had the same problem, started using Exxon and always from the same station.. no more pinging. Also stated in the owners manual.

JPGT_00

That is name brand right?

Tapeuup

Thanks for the eyeopener JP, kinda read over that.

Tapeuup

ditto, and when did it start rattling?

Bowman97

Since I bought it 3 weeks ago.

I'll check on the plugs.

GreyStang

Yes higher octane fuel is a remedy for detonation. Are you sure your hearing detonation?? Does it sound kinda like marbles rattling inside a metal can?