92' f150 shake rattle and roll

[widegauge]

I know that this isn't the forum for newer trucks but I am callin on all mec. out there to help me out. I have a 92' ford f150 4x4 w/5.8 A4od. here is the prob. I was setting at a stop light and I noticed that the truck was shaking a little. and then under acceleration away from the light it got worse....a lot worse. when it shifted into 2nd gear it went crazy. shaking all over the place....but if I let out of the gas it calmed down. it only did it under acceleration. but the motor isn't making any noises or missing or anything like that. it idles fine and sounds fine. but under the hood you can see that the motor is shaking a little bit when in park and running. it almost feels like it is the harmonic balancer is bad but it doesn't do it at the same RPM all the time....weird huh. well what do you got?

[widegauge]

sorry it is a 5.8 w/E4OD

[flyboy2610]

My first thought is a broken motor mount.

[Galaxie64]

Same here. motor mount.

[460 crew]

3rd that

[widegauge]

checked the motor mounts and the tranny mount....fine . a friend told me that, that was a sign of the tranny getting ready to crap the bed. so I put some lucas tranny treatment in it...............and nothing still does it. I am going to see if I can pull a code or two off of the trucks computer and see where that will take me.

[kid]

Code Scan the engine in KOEO and then KOER modes while in the KOER mode run the cylinder balance test. It will check all cylinders for equal power(imbalance) that you cannot even feel or hear. The code scan will also tell you if the E4OD knows anything about internal slippage or hydraulic bleed off problems.

A broken motor mount will not cause vibration. Lock the parking brakes block the rear wheels and open the hood. Fire up and drop the engine in gear and then look under the hood back edge at the top of the engine. If the mount is broke the engine will rise up on the driver's side. DO NOT POWERBRAKE for more than 5 seconds or you will buy a new tranny. :twisted: I can't say that enough.

[foghorn]

I have seen harmonic balancers go bad and spin so that they will go crazy at differnt rpm's. If it was me i would start there.
steve

[kid]

The only two times I have seen a Harmonic balancer go bad was the rubber failed after many years or a race engine that could snap rev. Typically on small block high rpm motors. At least on gas motors. Everytime we turned the governor up on a DT466 10 ton Dumptruck we would slip the balancer but that was from the hydraulic, fuel, air and external oil pumps dragging on the balancer.

[splavin90]

it's the motor mounts

[widegauge]

well guys and dolls, I figured it out, thanks for all the advice but I started the engine and started wiggling the spark plug wires and the #2 wire was touching the egr tube and was cross arking and killing the current to the #2 cylinder. burnt a hole in the wire, so I changed the wires and put a wire loom on this set and problem solved.......thanks again everyone.

[spartman]

I was gonna suggest getting a can of carb cleaner and spraying down you throttle body blades.

I know on the earlier trucks they would build up a layer of gunk there and cause running issues.