Bucking at around 45 mph??

[dcZ71]

I can't seem to figure out what is wrong. I get a bucking at around 45-50 mph when apply light throttle input. I can feel it in the steering wheel and the passenger can notice it too. Especially if a lug it on a hill and give it a little gas. I have to like floor it to get it smooth again.

Seems to run fine at all other speeds and accelerates smooth.


Anyone have ideas??

 

[Butch]

Check your U-Joints had one do that around 35 once before slinging a cap

 

[dcZ71]

Its not like a constant vibration or bucking its only when i apply a little gas at that speed, Is that what yours did?

how do you check, jack it up and spin the driveshaft??

 

[Butch]

Its not like a constant vibration or bucking its only when i apply a little gas at that speed, Is that what yours did?

how do you check, jack it up and spin the driveshaft??

It only did it from 35-40 under moderate acceleration in my old '91, only did it for a few days before it through a cap and dented the bed.

Just get under your truck and check your bolts on the u-Joint, if there the originals it might not be a bad idea to go ahead and replace them with some that have grease fittings

 

[Red97]

Try watching your tach. It could be the torque converter locking and unlocking. just a thought.

 

[dcZ71]

I know what you mean but this is not like that, it really starts bucking as if it had a misfire. its especially bad on inclines, if i just leave the cruise on it will buck with the slightest incline. I have to get over 60 to be ok.

 

[GWKP]

mine does the same thing! mine does it wen it goes into overdrive(45-55mph) and i meet a incline so i just give a lil gas to keep constant speed an it seems to "buck" (like there is slack somewhere) pretty hard sometimes but after that certain speed range its just fine, ive never figured it out so anyone please chime in for ts96 and myself

 

[dcZ71]

Yes dude exactly, and its so damn annoying cause I like to cruise at 50 in a 45 zone. Damn vortecs..

 

[GWKP]

man im tellin u ha... but there could be endless amounts of things that could cause it! im beginning to think it would be more transmission related like posted earlier with the TC locking an unlocking.. i had access to a tech 2 scanner so i hooked it up and monitored the data display and misfire graphic as i was driving and it started bucking but no cylinders had a misfire?? so ill look into transmission TSBs cuz trust me i no how annoying it is

 

[dcZ71]

Yeah i was thinking that too. I have no codes as well.

Ive replaced intake gaskets, cap/rotor, plugs, wires, pvc valve, cleaned maf, new cats... and nothin