Strange Drive Vibration
Fleet Mechanic
Joined: Nov 2015
Posts: 1,838
Likes: 187
From: NoVA
ForScan Lite on my iPhone does not pick up any misfires or injector faults. SnapOn scanner at my regular shop doesn't pick up any faults either. Truck idles normal. I get the shuddering/vibrations only when accelerating.
Cross-Country
Joined: Feb 2026
Posts: 51
Likes: 20
Just to throw another possible cause in here, i chased a vibration for quite a while before accidentally fixing it when i upgraded to a manual transfer case. Apparently a TC bearing was bad and causing a vibration at light throttle on the freeway.
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Trailering
Joined: Sep 2025
Posts: 15
Likes: 3
UPDATE
Think I have nailed down the issue. 97% sure it is poor coils and ignition causing this. This weekend going through each cylinder while engine was running I unplugged 1 coil at a time to pinpoint 1 running rough. I found 2 coils where the wire harness connector was loose! I secured them and it was instantly better. However, after I drove it a while it came back.
what I’ve found is that when the engine is colder it runs good. As it warms up, ignition gets poor and starts getting the misfire and shudder back. It only starts happening after engine is fully warmed up and running a while. So, I’m changing all plugs and coils with Motorcraft and will see what happens.
what I’ve found is that when the engine is colder it runs good. As it warms up, ignition gets poor and starts getting the misfire and shudder back. It only starts happening after engine is fully warmed up and running a while. So, I’m changing all plugs and coils with Motorcraft and will see what happens.
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Trailering
Joined: Sep 2025
Posts: 15
Likes: 3
Resolved!
It was definitely a rough running misfiring engine. Replaced all plugs and coils. Then still had an issue. Found a previous owner had replaced one of the wiring connectors from engine harness to coil and that wiring splice was causing issues. Been good for a while tank of gas now. And runnning smooth and strong.
More Turbo
Joined: May 2015
Posts: 633
Likes: 142
From: Staten Island, NY
It was definitely a rough running misfiring engine. Replaced all plugs and coils. Then still had an issue. Found a previous owner had replaced one of the wiring connectors from engine harness to coil and that wiring splice was causing issues. Been good for a while tank of gas now. And runnning smooth and strong.
MMNC (SS)(Ret)
Joined: Mar 2004
Posts: 11,606
Likes: 149
From: SE Georgia
immediately though misfire on reading initial post. glad you found it.
if it pops up again, verify your cowl seal isn't split and draining water onto the driver COPs. My V-10 had an issue with that. #6 & #8 would flood and ground out after a rain. Until i did the cowl fix mentioned in the Tech section and made sure the COP boot was securely fastened and lubed. Just a FYI for the future.
if it pops up again, verify your cowl seal isn't split and draining water onto the driver COPs. My V-10 had an issue with that. #6 & #8 would flood and ground out after a rain. Until i did the cowl fix mentioned in the Tech section and made sure the COP boot was securely fastened and lubed. Just a FYI for the future.
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