View Full Version : 99f250 superduty xlt 5.4 4wd 5speed

April 13th, 2019, 07:34 AM
Iím at a loss with this very intense slapping/flapping noise underneath the dash / engine bay after 35 mph and it gets louder as you drive faster. Iím hoping itís something inside the dash and not the engine piston slap or valve train . It does have bad exhaust manifold hardware/ a few broken studs but this isnít that type of knocking. If anyone has an idea what this is , piston hitting a spark plug, piston slap or anything is appropriate the advice. Iím not lucky enough to have it actually just be in the dash vents or what not but it really sounds like itís in the dash

April 15th, 2019, 09:35 AM
Have you manually worked the throttle cable from under the hood? You should be able to hear better from under the hood with it in the driveway.