Coughing 460
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Joined: Feb 2005
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Coughing 460
Our parents has a E-350 with a EFI 460. The 460 has a rolling RPM idle and has a random cylinder miss fires under part throttle. However, at more than part throttle to full throttle, the engine runs great. My brothers replace the distributor with a brand new reman one. replaced the the spark plugs and wires, replaced the fuel filter, checked for vacuum leaks, and I checked the fuel presser, which was within Ford spec. Since this 460 is a 1994 model year, the OBD I system doesn't pinpoint what, or where the problem is. We're down to thinking maybe it's a bad DuraSpark ignition module, or a bad ECM. We just want to stop throwing expensive parts on a 25 year old motorhome that's five to ten years away from retirement. If anyone who works on EFI 460s can tell us what's wrong with ours, please let me know, thanks.
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Joined: Apr 2004
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Rolling RPM idle could be a sloppy timing chain. Hard to do on a 460 but if you can pull the cap, watch the rotor when you rotate the motor by hand. Reverse the rotation and see how far the crank goes before the rotor moves. If it's more than 5 degrees it could be the idle wandering all over as the chain allows the cam "float" a bit.
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