munnson89

Hello and thanks in advance for any help.
I have a 1996 F-150 4.9 Automatic 4x4 regular cab. Approximately 97k original miles. I am having an issue that I can't quite seem to pinpoint. Once truck is in overdrive and I am just maintaining speed I get a strong vibration through the gas pedal and it remains until I coast or accelerate. Don't feel it in the seat or the steering wheel just very strongly through the accelerator pedal (much like driving on the rumble strips on the side of the road) I do get the vibration for very short periods of time in lower gears but not like I do in overdrive cruising at 55mph. I have read many of the forums and researched the E4OD torque converter shudder but I am not 100% convinced that is what I have going on. If I maintain pedal pressure and lightly tap the brakes while cruising at 55mph the rpms raise and the vibration goes away and then returns once the rpms lower. This tends to point to torque converter. But, if I stop, put the truck in drive, hold the brake down, and rev the engine while in gear with brakes on I get the same vibration as I hit I would say 12-1800 rpm (don't know exact as I don't have a tach) so this seems to point to the vibration being dependent on engine RPM. This is what has me second guessing the torque converter. If anyone has any input for me that would be greatly appreciated. Thank you.

Steve83

It's most likely a combination of problems, including:
- broken engine mounts (VERY common)
- misfiring (check plug gaps, wire resistance, cap/rotor condition)
- accelerator cable fouled against the dipstick tube (TSB in this caption)


https://www.supermotors.net/registry/media/724166 (for phone apps)

Do you know that the truck has an E4OD? Read this caption & fill in your signature here with all the truck's details:


https://www.supermotors.net/registry/media/72354

munnson89

Thanks for the input. I think you may very well be correct with the motor mounts. I checked the passenger side first and it is very rusty and the rubber is quite deteriorated looking. When I start the truck the engine rocks quite a bit back and forth and the motor mount lifts quite a bit. In gear holding brakes in reverse passenger side lifts quite a bit and rocks to drivers side. In drive the passenger side of the engine pushes down quite a bit. I know the 6 makes a good amount of torque so not sure how much movement those mounts should have if any. Also how terrible of a job is the mount replacement? Thanks again. Also checked plugs and they are very white so looks like they are burning very hot which I believe means the truck is running lean. Pulled codes and I have three for 02 sensors and the 0171 and 0174 codes.

Steve83

There are many ways to change the mounts; some easier - some harder; some righter - some wronger... This shows an easy wrong way:


(phone app link)

The links in that caption show another way.

Don't pick a word or part name out of a code definition. Read & understand the COMPLETE definition, and diagnose accordingly. This caption contains my list of definitions, compiled from Ford's lists:


(phone app link)