I bought a 2003 V6 5 speed Silverado with 50,000 miles a few months ago and have been very dissatisfied with its poor highway performance. I do have oversized 265/65 tires (which I believe is stock size on ls models anyways) but I don't see how this could make THAT much of a difference. I do have a hard tonneau which I would think could almost make up for that... Acceleration is almost non-existent in 5th gear, around 8 seconds full throtle to accelerate 65 to 70. Accelerating 45 to 50 in 5th is much more bearable to the point where I almost only use overdrive in the city. It almost seems like there is no torque between 1800-2100rpm's. I did borrow a scanner to check codes and nothing came up. I got a v6 for gas mileage and now its seems like I would have probably been much better off with a v8. I'm averaging only about 15mpg on the highway and about 18 in the city. Well I'm hoping someone has some ideas to what this could be. I hope this isn't just a normal thing. Because I don't know how much longer I can stand this truck.

 

5th gear is not made for accelleration, just for saving milage when cruising. You will actually lose milage by staying in 5th and trying to accellerate. At 45-50 I would stay in 4th. These trucks have alot of power, but I think you are trying to get power from too low rpm. The power band is probably from 2300 up, so that would explain the problem you are having. If you want power, get the rpms up.

 

How many miles does it have? It may also help a little bit to do a tune up on it if the mileage getting on up there.

 

v-6's in ext cabs are real turds...I drove on today and it sucked

 

I know 5th is not for acceleration but you at least have to be able to adjust your speed on the highway which I can't really do. I have to be in 4th to do that and 3rd to even try to pass. My main question is it normal that I have some torque between 1500-1800rps and then I hardly have any until at least 2100.

 

mine is not a speed demon by any means but nay is it a turd either!

It sounds like you need to have a tune up and mabey check out some of the mods that have been done to the 6 packs.

as far as the shifting goes,down shift to get her in the higher RPMs. I too have experience the"*******" at highway speed but With an automatic I can force it in to a down shift and that seems to remedy the problem. Don't give up just yet!