Getting A Shake

[Cody_350]

okay so lately my trucks been acting weird. I have a 1999 Chevy Suburban K2500 with a 5.7 350. when I'm accelerating too quickly I guess, it shakes. this is what's been happening, I don't know how it started. I usually run the gears when I'm driving because I like going fast lol, well now if I'm in 2nd gear and hit 55-60 mph it'll start shaking if I'm applying gas, if I let off it doesn't shake at all but if I give it gas again it'll start to shake. then I have to let it slow down to about 50 or let it hit 3rd gear and it'll act normal again unless I jump up to 75mph. what is this? I bought U Joints today thinking maybe it was that but I'm not sure, has anyone else had this problem? I only have a cheap programmer on my truck but I don't think that's it. sound like a transmission problem? I have a small amount of play in my Differentials as well but I'm sure that's not it.

 

[df2x4]

By "run the gears" what do you mean exactly? If you're manually shifting an automatic there is literally no reason to do that unless you've actually installed a manual valve body. You're not going to go any faster and you'll probably wear it out quicker. Programmer could be the cause, especially if you're running a different octane than what it's calling for. If I were you I'd go back to the factory tune and see if it makes a difference. Programmers aren't really going to give you any power or speed anyway. If you want a real difference, pay a real tuning company like Black Bear to build you a custom tune. If going back to the factory tune doesn't fix it, I'd be looking at your ignition system and transmission.

 

[Cody_350]

when I say "run the gears" I mean just running up to 3rd quick and letting overdrive kick in, it's always in Overdrive though. the programmer was bought to increase gas mileage which went up by 2, I've only kept it in the economy tune and it worked fine for 4 month and now I'm experiencing the problem so...

 

[Rusty Nail]

Check transmission fluid.