- 1997 f150 4.6l 4x4 off road edition-

Back again with more questions and issues. Now I have an issue where if I get on the gas from a dead stop any more than quarter throttle I feel a pretty heavy thumpthumpthumpthump until I let off the gas. It feels like something is lightly binding they way it acts. From the way it feels it seems like a mount could be busted somewhere allowing it to move and bind up. My transmission mount is brand new, and I haven't checked my engine mounts yet.

If I ease onto the gas to like 3 mph then get on the gas its perfectly fine. Its more prominent when I am on a decently steep hill trying to take off, especially with my 16 foot landscape trailer for work (being that I have to get on the gas kinda hard to even start moving). It doesn't seem like it ever effects anything when I do it on purpose to make it happen, and what I mean is I don't lose power or no noise occurs, just the repetitive thumping. I'm worried about some kinda spline in the rear t case or transmission slipping, so I try to avoid it unless I'm showing somebody or trying to take off up a hill.

Anybody have any clue what could be causing this to happen or stuff i should look at? I don't really know where to start other than checking my mounts.

Thanks for your time and help in advance!

 

I would've said a misfire but you reported no loss in power.
When I had a misfire, it would only do it on hard acceleration, or going up hills, etc. Ended up being my ignition coil, which was a simple fix.
I'm not an engine whisperer so I really can't say for sure.
Does it do the thumping if you rev it in park/neutral?

 

No its nothing with spark, it only does it in drive and under the above circumstances

 

Wheel hop? My truck does it really bad, but it is LOUD

 

Lube your driveshaft slip yoke and replace the ujoints.

 

My joint on the yoke side is new and I already have a new one for the other side going in this weekend. And do u mean the slip joint? Cause i only have a slipjoint on the front driveshaft, and it does need lube its popping when braking so I took it out. My rear driveshaft is a solid shaft no carriers or slipjoints

 

It rides like a Cadillac usually, and I can drive it comfortably without this problem happening. It only happens from a stop to a decent amount of throttle right away. Wouldn't wheel hop be consistent?

 

Bump need help

 

Could it be bands slipping under load in tranny?

 

If you can't figure out what it is right away, it'll help to figure out where it is. You say your front driveshaft is out? That's good, put the rear on jackstands and start the truck. See if you can duplicate the noise. If that doesn't work, walk beside it while somebody hits the throttle and try to localize it that way.