Hey guys,

5.4L w/ 81000 has developed a shutter. When driving if I accel up to around 45mph, then let off the gas for a few seconds, then lightly press on the gas again the engine kind of shutters. Nothing violent but very noticable. It continues until you press on the accelerator harder or it seems to go away on its own around 55mph. Replaced air filter and fuel filter. No difference. Doesn't matter if tranny is in overdrive or not. No ses light and no pending codes when using my downloader. I have seen similar write ups and usually leads towards an ignition problem. I am planning on changing plugs tomorrow, but don't want to throw 8 coil packs at it yet. If the plugs don't fix it I might wait until it gets bad enough to throw a code. Not sure how to isolate it to a cylinder without a trouble code. Any advice is much appreciated.

 

If it is constantly at the same speeds, it could be torque converter shudder. If so, a transmission flush may be in order. Go to your local parts house and buy a bottle of anti-shudder for the transmisspon fluid. Trans Medic makes a good product. Try this first.