When I am driving down the road I have noticed that the truck seems to vibrate quite a bit when I have the gas pedal pushed and then gets smooth when I release the gas pedal. I thought it might be the tire balance but it seems to be dependent on the gas pedal being pushed. Does anybody know what might be causing this? Thanks.

 

The truck is a 1999 F150 4x4 ex.cab, 5.4 V8.

 

It COULD possibly be the Transmission...Is it almost like a chatter? To properly diagnose it, you'd have to describe it more...

 

transmission, driveshaft, rear end, clutch fan, dirty injectors, dirty maf, clogged egr...

 

You describe the trouble perfectly. I have the same problem with my 114K miles 97 F-150 and I am too cheap to pay someone to fix it. No trouble code, worse at low speeds, worse when hot.
I checked the throtle position sensor with a VOM but no bad spots. It better not be the transmission. I baby my 97. If you hear of a fix, let me know.
Thanks

1997 F-150 4x4 ATX 4.6L

 

I have a 2000 F150 XLT. About a week ago my truck started shaking when driving on the highway. It would happen in the first ½ hour of driving. It would really shake like it was coming from the tires or the front end. I put the shifter into neutral to see if I could tell if it was the engine or not. When in neutral and I stepped on the accelerator the engine seemed smooth.

The shaking would go away after about 10 minutes. But would happen both in the morning and on the way home from work.

After about a week I just happened to walk in back to lock my tailgate and I could smell brakes. I reached down and touched my rear hub and burnt both finger.

I have 4 wheel disk brakes with shoes on the rear for the emergency brakes. When I jacked up my truck and took the rear wheel off I found that the top level that is connected to the emergency brake cable was corroded and the shoes were not returning all the way.

I cleaned the level and the truck rides smooth. I would have never guessed the problem if I had not walked in back and smelled the brakes. I though for sure I had a front-end problem the way the steering wheel was shaking.

This may not be your problem but you might want to check it out. You never know!

Good luck, I hope this helps.

 

The viberation seems to be gas peddle position and torque sensitive. Once the engine starts to viberate such as climbing a hill or increasing speed while pressing down more than normal on the gas peddle, you can stop the vibration by pressing harder or releasing off the peddle some.

The viberation seems to be coming from the engine and passes turn the transmission right down to the road as if you are driving over a series of groves cut into the pavement.

My add-on vacuum guage shows no unusual reading.

The condition seems to be getting worse with time, so I expect it to be easier to find as time goes on. Since I drive mostly at highway speeds, I have not had it checked yet.

 

I have this same exact issue with my 2000 Expedition (5.4L)-- just as Calinkus described it. It seems also as if you can almost feel the vibration in the gas pedal itself. And the noise that is generated is inconsistent.

I notice the problem the most when going up a hill. If I left off the gas a little or push down a little, the vibration and noise will go away.

 

I had the same exact problem returning from a trip to Florida a few weeks ago. Push on the gas, the floor vibrated. Let off the gas, engine ran smooth as silk. It almost seemed like I had a U-joint going bad. It was worse going up hills or under a load like acceleration from a standing stop. I asked my local Ford dealer and he said it sounded like transmission shudder. He offered to replace the fluid and filter and said that usually fixes it. I replaced the fluid and filter myself and the problem went away. I have the 4r70w transmission. I drained the converter and the pan and replaced the filter. I filled it with Pennzoil semi-synthetic Mercon V fluid. Mercon V is labeled on the trans dip-stick.

It was not an expensive thing to do and I needed to replace the fluid anyway so I figured what have I got to lose ? I probably ran about 35-40k miles since I last replaced the fluid and filter.

Good luck.

 

Ronhop,

Thanks for that info. I was wondering if it could be transmission related (just hoping that it wouldn't be something serious). I guess I'll have to go out and change my transmission fluid and see what happens.


Thanks again!

 

Well, I changed my transmission fluid, and I still had the same problem. So, I took my Expedition into the Ford dealership and went on a ride with their transmission specialist.

He told me that with the 4R70W transmission, a fluid change with Mercon will take care of the vibration. He said the actual problem is clutch chatter in the torque converter. With the 4R100 transmission (what I have), however, a fluid change won't take care of the problem. So, they replaced the torque converter and said they fixed the problem.

I pick up the Expedition and drive it off. And the same throttle-position sensitive vibration was still there!!! Damn Ford dealership sucks!

So, I took it back in a couple of weeks later and went on another drive with an "engine" specialist. This guy confirmed that there was nothing wrong with the engine itself, so he was wondering if it could be the transfer case. Well, after checking things out, the cause of the problem was the transfer case!

I don't know what they fixed yet because my work order is still open for a couple of other things, but I'll let you know when I get the full explanation.

 

When I was looking for a Mustang to buy, I noticed this problem with the first two mustangs I drove. They both were 5.0's w/ manual tranny. One was a 93, the other a 94. They were both at the 100K mile mark. After that, I strayed away from them. Everyone I talked to said they never experienced it before.

If someone has an input to what this might be, please reply. I still would like to have a one as a toy, but too scared I might run into big, costly problems. I know this is on the wrong site, but maybe the problem is related to the f150's.

 

Well, there was an apparent problem with the transfer case clutch, so they replaced it (part number XL1Z-7C108-AA) and something else (possibly a seal--"SE-R/T" part number F7AZ-19554-EA).

Everything's good now, and there's no more vibration.