2003 Silverado 4.8 performance question...

I just purchased this truck with 400 miles on it. It's an extended cab, standard box, 4x4 with a 373:1 rear end. I couldn't stand how quite the truck was so, I went to the muffler shop and had them install a Flowmaster 40 Series muffler. I did not add dual exhaust. They just cut out the old muffler and installed the flowmaster. Now, I have only had the truck for a week when I did this. My truck seems to be slow from a dead stop (ie. won't even turn over the tires). If I get on it at 25MPH, the truck moves.

A friend of mine has a 99 Silverado, 4.8, 4X4, Reg cab, Short box with 33" tires on it. I race him from a stop light and he kicked my butt off the line and I caught him with no problem.

Anybody have any ideas if I need to reprogram the computer since I changed the exhaust? Did I hurt my performance?

I didn't buy this truck to race it (I have a Mustang for that) I am just disappointed in the power off the line.

Thanks,
Dan

yeah i have the same problem in my 99 ext cab.it has the 5.3 in it though. off the line i got nothing, it wont even spin a tire!!
i took it to a shop and got a single in dual out flowmaster with turndowns but i got nothing. whats wrong? is this normal? what can i do to correct this?
any help would be appreciated!!!!

My friend has a 2001 Silverado ext cab 5.3 and that thing runs like a raped ape! I can't believe that people will read my post but, won't respond.

Dan

I just got a 2k3 Silverado 1500, ext cab, Z71 with the 4.8L currently stock and I couldn't get the tires to squak off the line from a stand still unless I cheated. My dad has a 2k1 1500 with the 5.3, identical everything else and I can usually get that to give me a little bit of noise if I try. When I asked one of the mechanics from the dealership that I bought the truck from when I was deciding between the 4.8 and 5.3 ($$$) he had told me that there was only a 15hp difference between the two engines but the amount of torque that the 5.3 had was greater than the 4.8 so from what it seems if you want to get it to make some noise you'll have to do some performance enhancers.

I just got a 2k3 Silverado 1500, ext cab, Z71 with the 4.8L currently stock and I couldn't get the tires to squak off the line from a stand still unless I cheated. My dad has a 2k1 1500 with the 5.3, identical everything else and I can usually get that to give me a little bit of noise if I try. When I asked one of the mechanics from the dealership that I bought the truck from when I was deciding between the 4.8 and 5.3 ($$$) he had told me that there was only a 15hp difference between the two engines but the amount of torque that the 5.3 had was greater than the 4.8 so from what it seems if you want to get it to make some noise you'll have to do some performance enhancers.
:iceslolan something must be wrong with your z-71. my base 2003 4x4 silverado 4.8 will bark the tires at 30mph when i floor the gas.It has 3.73 gears and heavy duty suspension pkg. and trailering pkg. thor48

Hmm, I can tell it comes close to squak'in but it doesn't, I do have the bigger tires on it (can't remember which package that came with) so who knows, I'm probably going to do a few mods to get the HP up but then I'm planning on eventually Lifting it and throwing on bigger tires so who knows what it'll be able to do eventually, I'm not too worried about it, I can keep up with some of my buddie's cars and whoop all their trucks so I'm currently satisfied :biggrin:

weird if i mash the pedal on my 04 4.8 from a dead stop it will chirp for a bit and if i dump the clutch at 3k it will smoke through 2 almost three gears the difference...... I have a manual transmission. I really want one of those volant ram air filter boxes
but to answer the question try starting your auto trannie in first because by default auto boxes like starting in a higher gear (for best gas mileage)

i dunno...i got a 2002 extended cab silverado..and if turn my traction control off i can spin the tires smoke the shit out of my tires....lol...but then again i have done a few performance mods....i put flomaster exhaust, k & n cold air intake, hypertech programmer and a beautiful set of edelbrock header....im gonna go dyno my truck soon to find out what the rear wheel hp is....but it spins em off the line....
josh

i dunno...i got a 2002 extended cab silverado..and if turn my traction control off i can spin the tires smoke the shit out of my tires....lol...but then again i have done a few performance mods, and i have a 5.3....i put flomaster exhaust, k & n cold air intake, hypertech programmer and a beautiful set of edelbrock header....im gonna go dyno my truck soon to find out what the rear wheel hp is....but it spins em off the line....
josh

I have a 2000 model Standard cab, short bed with a 5.3, and it did not spin tires at all when I first got it, after some time on the engine, about 30k, it will light them up if I want to.

I want a higher stall converter, I think that will help. :icon16:

What kind of rear end do you have? If your friend has the factory diff w/out limited slip he is going to screech the tires way easyer than if you have the factory limited slip. I have a 99 5.3 with 33's and if you hold the brake and give it quarter throttle then let off the brake and flore it it jumps off the line...you should try that. I was sick of the 33's bogging my truck so i put 4.56's and an Auburn locker in the back. WOW what a difference. I can burn out till my tires pop. I have yet to take it on the quarter mile, i know i would give those rice burners a run for thier money. The Hypertech, intake, and exhaust helped alot. When i stiffend the tranny with the chip it made it so i could chirp second gear with an automatic. Before looking at getting engine mods you should consider 4.11 cause who needs to go 150 on the freeway anyways; and plus your truck has a top speed limiter.

i have a 2000 gmc sierra with a list of stuff done to it and with 3:73 i cant spin the tires at all, it sorta dogs until like 1700 rpm then take off like a raped ape!!! i also have the factory locker. not sure i had the extra money i would like to put 3:85 or 3:90 gears in just for the extra off the line jump

if your going to go through the trouble of putting gears in go with 4.11s. I just ran a 7.5 second 0-60 with my truck. I have a k&n intake flowmaster exhaust and a hypertech chip. The 4.56s are equivilent to 4.11s on my truck because i have 33 inch tires. I still get 13 -15 mpg.

I have a 2003 Z71 5.3 and I have had no problems spining the tires or getting good jumps off the line. I put a 40 series flowmaster, AEM Brute Force cold ait intake, Mass air flow sensor, Bosch platinum 4 spark plugs on it and that thing has no hesitation or lack of power at any time. I wouldn't been able to do it stock , but my 5.3 has beaten my friends HEMI several times when we line them up. I saw the best results form the intake and the Mass air flow sensor, but believe it or not the plugs made a big diffrence and it is a cheaper route to go fo a quick 7hp at the wheels.

I have a 2003 Z71 5.3 and I have had no problems spining the tires or getting good jumps off the line. I put a 40 series flowmaster, AEM Brute Force cold ait intake, Mass air flow sensor, Bosch platinum 4 spark plugs on it and that thing has no hesitation or lack of power at any time. I wouldn't been able to do it stock , but my 5.3 has beaten my friends HEMI several times when we line them up. I saw the best results form the intake and the Mass air flow sensor, but believe it or not the plugs made a big diffrence and it is a cheaper route to go fo a quick 7hp at the wheels.


What rear end do you have and is it extended cab. because i am waiting for the day the hemi happens to stop next to me a light!!!

I have a 2003 Z71 5.3 and I have had no problems spining the tires or getting good jumps off the line. I put a 40 series flowmaster, AEM Brute Force cold ait intake, Mass air flow sensor, Bosch platinum 4 spark plugs on it and that thing has no hesitation or lack of power at any time. I wouldn't been able to do it stock , but my 5.3 has beaten my friends HEMI several times when we line them up. I saw the best results form the intake and the Mass air flow sensor, but believe it or not the plugs made a big diffrence and it is a cheaper route to go fo a quick 7hp at the wheels.


What rear end do you have and is it extended cab? i have a k&n intake and a masss air flow sensor (which i didn't see a difference with) too. those hemis are supose to run somewhere around 15 and im not sure if my truck will run a 15. i guess i'll wait for the day the hemi happens to stop next to me a light!!!

[QUOTE=gtlegacy]if your going to go through the trouble of putting gears in go with 4.11s. I just ran a 7.5 second 0-60 with my truck. I have a k&n intake flowmaster exhaust and a hypertech chip. The 4.56s are equivilent to 4.11s on my truck because i have 33 inch tires. I still get 13 -15 mpg.[/QUOT

i'm not to fimilar with how the gears affect gas millage or anything really. i just know that my buddy has the same truck as me only he has 410's and he gets 15 on the highway. and i would like better gas milage then that and i dont really want to sacrafice my top end either. so i figured 385 or 390 would be in the middle and give me more power off the line where i need it and not affect my gas to much. it seem that you know more then me could you maybe help explain what you know. thanks

I can't keep my 4.8 from spinning. I guess that has something to do with the mods and no weight on the rear end. :) I currently have 3.42 in my truck, but if I were to go any higher it would be the 4.10s. Most of my friends that were running the 3.73 gears and stepped up to the 4.10s average a loss of about 2-3mpg. My best time of a 15.2 was with a terrible 0-60 due to traction issues. This was before the stall, so I went ahead and ordered some cheap rims and drag radials. :biggrin: That should do the trick for the traction issues. I also plan on ordering the cal trac bars in the near future.Now, when I feather it off the line and then go wide open, I catch second pretty aggresively, and get a real firm 2-3 shift. I would suggest a shift kit and corvette servos to anyone looking to liven up there shifts.

. I would suggest a shift kit and corvette servos to anyone looking to liven up there shifts.

you would suggest both to run at the same time. i was thinking about getting the corvette servo. but i am going to see how the chip is from Westers garage. it looks like it is going to work with some of my mods already. does anyone know anything about westers garage chip.

Any aftermarket chip or tuner will all pretty much do the same thing. If you're really serious about performance, I would suggest either ls1edit, a nelsons performance tune, or the predator programmer. Most of these deal with the main trouble of our stock tunes, which is torque management. As far as using the programmers for shift firmness, they all just raise the tranny fluid pressure, so if you did the servo or the shift kit, you would need to undo any firmness you set with the program or it would surely kill the tranny.

Any aftermarket chip or tuner will all pretty much do the same thing. If you're really serious about performance, I would suggest either ls1edit, a nelsons performance tune, or the predator programmer. Most of these deal with the main trouble of our stock tunes, which is torque management. As far as using the programmers for shift firmness, they all just raise the tranny fluid pressure, so if you did the servo or the shift kit, you would need to undo any firmness you set with the program or it would surely kill the tranny.
torque management if i get rid of that doesnt it hurt my drivetrain? i have a hypertech power programmer and i has seemed to do pretty good. but i was looking for something that would help out better then that.

torque management if i get rid of that doesnt it hurt my drivetrain? i have a hypertech power programmer and i has seemed to do pretty good. but i was looking for something that would help out better then that.

Torque Management is a way for GM to control accessive abuse to our vehicals. When you stall it up, spin the tires, and even on the shifts the computer pulls timing to ease the torque on the drive train. For stock trucks it only effects it slightly. I have noticed the more hp you create the bigger the problem becomes. You cant get rid of it in you computer, but you can pritty much trick it into never coming on. I would only sugguest this after the servos and shift kit, though, because with the firm shifts, you shouldn't have anything to worry about.

so it really only retards timing in the shiifting process. i think i have noticed that. because i have a hpp3 with the shift firmness on and i have my truck running up to 6000 rpms and some times it slams in to the next grears and other times it does what i call a butter shift. so maybe that would be my torgue mangement working?

Most likely that is what you're feeling.

my tires light up off the line,mods worth 3000, friends kick ass,only spent bout 1200 run mid 13 at track all day i think yall be happy with a k&n hypertech and a gear swap about700$ definately smoke tires without cheatin

"The Ladies Man", nice truck.

I don't see how you guys could be having trouble spinning 285 hp with .373 gears, lol! My 1992 350 with .342 gears and 265 Wrangler TD tires will spin from a dead stop without holding the breaks!

Anyways, I think the .373 gear is the best all around gear there is. It should get you out of the hole really fast, and still not give up much on top end. A .410 will break your kneck out of the whole, but run out of steam at 80 mph. And thats the same with a .390 gear. They do great untill 60 mph, but start giving up from then on. I've always wnated a .373 gear for my truck. My .342 does good from a dead stop, but I can feel it giving up from liek 35 mph-55mph, but from then on it really starts coming on. Your .373 gear should be good out of the hole, best in the 30 mph-60 mph, and good every where else. And plus you probably are getting close to 20 mpg with it too!

My father owns a 02 silverado ext cab swb 2wd w/ a 4.8 the only mods that have been done are exhaust (flowmaster delta force muffler) & a spectre cone air filter. each and every time he stands on it it turns crossways and smoke rolls off the tires. i do not know why, but its pretty fun.