Greetings all, I just bought a Silverado so thought I'd join a forum for it.

It's a 2002 1500, Z71, 4.8L, 69K miles. I'm very happy with it except for a couple things.

It doesn't seem to have much power. On a gentle incline it won't maintain highway speed (55-60) without unlocking the TC. On anything more than a gentle incline it takes quite a bit of throttle and a downshift to 3rd to maintain highway speed. Pulling a boat (17' I/O, not a very big one) sometimes I can only do 45 in 2nd on inclines. I'm not talking about large hills here, just the normal ups and downs on freeway ramps.

Second problem is power. EPA rating is 15/18 but in 4 tanks I've gotten 14-14.5. I would have preferred the 5.3L but consoled myself with the thought that the 4.8 should have better gas mileage. Well, it's a wimp and it gets bad mileage to boot. I didn't expect this truck to sip gas but I think it should do better than it is.

My wife has an '04 Suburban, 5.3L and a lead foot. This Sub got 17 mpg around town on the one tank I checked, and has much more power than my pickup does. anyone else keep detailed track of their mileage, and want to share what they get? Also whether you're satisfied with the power your truck has? I've seen claims in the archive of over 20 mpg.

I haven't done anything to it yet but will do plugs, air filter, and check tire pressure soon.

thanks for any replies, looking forward to being a member.

--steve

 

my 06 5.3 gets 16 highway and 13 city. It has 5000 miles on it so far. It has plenty of power except when pulling a trailer. It will keep the speed but shifts down and lets her rip when I have the cruise set

 

You've fallen prey about gas mileage. The reason Your wifes' 5.3 gets better mileage is that the engine has more power requiring less accelerator to move it to a comperable speed. Less accelerator equals less fuel used. It gets much worse when towing because the lack of power requires You to push the throttle to what is a wide open position and it comsumes fuel at a phenominal rate at WOT. I don't know what it weighs or what Your rear gearing is, but They work together. It's just underpowered, I can't say it any simpler. Do the basics, Up the tire pressure to 45 psi, Change all fluids to synthetics ( Mobil 1 ), Get a free flowing air filter and put a free flowing exhaust on it. That's about all you can do cheaply. The tires may be suspect. If it's got an aggressive Tread pattern ( off roar type ) then look into a milder M/S type tread. I know a fellow Who did this and went from 13 MPG to 19 MPG with no other changes. Good Luck and thanks for listening.

 

That sucks for mielage for that little engine, not much better than my 6.0 (12.9 anywere I go, any thing I do) and a lot less power.

 

That's what I've heard from friends that have the 6.0L engines. My '99 5.7L Vortec in a 4x4 suburban averages about 17 mpg on the highway. I really don't know why the 6.0's don't get better mileage. Try doing some of the "basics " I posted earlier. Never know - might work.

 

my '06 crew 4x4 gets normally 15.8 to a max of 18.4. it is a 5.3.

 

Hey, I'm not sure what's different between your 02 and my new 06 but my sticker mileage is 16/21 mpg. I feel that during the week I'm getting about 20-22mpg but as soon as the weekend comes and the throttle gets heavy from blasting around for fun, the mileage drops to probably 14mpg. Every time I calculate it I'm getting around 17 on average. I haven't had any problem with power, however all I've hauled is a few loads to the dump. I have installed a cool air intake from S&B which has made a noticeable power increase. I haven't noticed a big difference in mileage with this upgrade but I am about to install a Gibson cat back exhaust. After that mod I will more accurately calculate the mileage and record the HP/TQ gains over stock.

 

IF you are going by the computer. Mine is off by a half a mile to high. I get around 20 on the road and 15 in town.

 

Yeah, I have a 2006 4.8L 4x4 and I got 18 mpg last tank. 8200 miles on the motor. I also pull a 17' fiberglass boat (~2200lbs). When I tow, I use tow/haul and leave it in 3rd.. no overdrive. I have plenty of power when doing this. I don't expect great mpg when towing. If I tow to the ramp and back one time during a tank (50 miles round trip) my mileage only drops to about 15. I don't lead foot it to work and back.

Also, check your rearend gearing. You should have the 3.73 rearend, but if it got swapped at some point before you owned it, that would explain your issue. The 4.8L is rated for 285 hp and 295 ft-lb torque. The 5.3L is rated at 295hp and 330 ft-lb torque. That's not a huge difference. But yeah, the mpg thing is a wash between the 2.

 

BY chance do you have larger wheels/tires? Going up a bit in size will hurt performance & economy.