Spark knock or exhaust leak?

Asked by Feb 20, 2016 at 02:20 AM about the 2004 Ford Mustang Coupe

Question type: Maintenance & Repair

My car makes a rattle sound when accelerating but
I already tried higher octane gas and changed egr
valve. When I turn it on I here like a doing going
from the manifolds. But it does t last long. What
could it be?

1 Answer

293,885

If the higher octane hasn't helped, it could be an exhaust shield around the catalytic convertor that has rusted loose and rattling. You can clamp it down, tack weld it back in place or remove it. Don't let a muffler shop sell you a new convertor if that is the issue.

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