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2005 Silverado 1500 5.3L V8 Z71 slow acceleration problem

This is a discussion on 2005 Silverado 1500 5.3L V8 Z71 slow acceleration problem within the Performance forums, part of the General Discussion category; Ok so for starters the truck is a 2005 Silverado 1500 w/ Z71 and Flexfuel 5.3L V8 under the hood. ...

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    2005 Silverado 1500 5.3L V8 Z71 slow acceleration problem


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    Ok so for starters the truck is a 2005 Silverado 1500 w/ Z71 and Flexfuel 5.3L V8 under the hood. Has around 140k miles on it. Pretty much as stock as they came. Also I keep it in 2WD unless I possibly need 4WD and then put it in Auto 4WD, or if I know I need 4WD I put it in which ever range I need it in.

    The truck drives great, but lately I've noticed a slight increase in fuel mileage (like 1.5 MPGs better).

    However, I've also noticed that on take off it kind of acts like a stock 4.8L, meaning it takes forever for the RPMs to get up there for it to do anything. It acts like this until it's maybe up to 35-40 MPH and then it gets to going. Now this is taking off from a dead stop, pedal to the floor. I have noticed though that if I let off about half way after getting up to like 10 MPH, it acts like it's getting better performance and all that.

    It doesn't really bother me that much that this is happening because I don't race the truck, but I do want to know what could be causing this to happen. I haven't done any work on the engine or anything like that yet, but I have used some injector cleaning stuff you put in the fuel tank and let it run though (I did notice a little bit of difference after that but only for a couple days), cleaned the injectors with sea foam, and have cleaned the throttle body and checked the air filter.

    I don't have any codes going off other than a knock sensor code from having to go through a 2 mile long road river (what I call a road that has water flooding over it more than 6 inches) and apparently got water on top of the engine into the bores for the sensors. But this problem was occurring before I had to do that.

    One thing I think it could be is the electronic controlled throttle body as with my older 2001 that was run by cable, I never had this issue. I would say it could be relaying slowly, but if I'm already up to speed and hit the gas it's an instant gain. Same with sitting and idling and hitting the gas, only happens with I'm first starting to accelerate.

    So I think I've possibly given enough information to ask this question. What could be making this problem occur?

    If anymore info is needed I will give as fast as I can.

  2. #2
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    Re: 2005 Silverado 1500 5.3L V8 Z71 slow acceleration problem

    First, stop using the auto 4wd.
    At 140k have you ever done a basic tune up? That could help.

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    Re: 2005 Silverado 1500 5.3L V8 Z71 slow acceleration problem

    With early 4.8/5.3/6.0 motors, there was an issue with carbon buildup in the throttle body, they had to be cleaned at least annually.

    If yours does not have the cable, not sure if that is still an issue, pull the air tube and open the butterfly in the Throttle body and take a peek.

    Tune up is paramount, plugs/wires by 140K, air filter and fuel filter as well. If those haven't been changed, do it.

    Auto 4wd has it places, on dry pavement, I keep it in 2WD mode always.
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    Re: 2005 Silverado 1500 5.3L V8 Z71 slow acceleration problem

    Dirtyhick42-
    When I said I use Auto 4wd, i meant like maybe once every other month, as it's usually either full on 2wd or full on 4wd.

    Joe-
    I have kept up with cleaning the throttle body with deep creep and a rag so it's clean through there, as a matter of fact yesterday was my day for cleaning it and cleaned it before posting this.

    Both-
    On the tune-up, air filter is clean, spark plugs look fine and haven't checked the fuel filter. Didn't even think about the fuel filter actually..


    Did notice today headed to town that if I take up full throttle its around 30 that is starts picking up not 35-40 like I said before. Also, I tried half throttle take off to see if there was any difference with the sluggishness - if you wanna call it that - and it was like a wild child taking off, but if you go onto full throttle it acts like it's bogged down for a second and then picks back up.
    Last edited by chevcamo; 07-08-2011 at 02:16 PM.

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    Not Really Bob
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    Re: 2005 Silverado 1500 5.3L V8 Z71 slow acceleration problem

    Sounds like the truck's PCM is doing the job GM programmed it to do. When you go WOT at a low speed/low rpm, Abuse Mode is enabled and the computer pulls a lot of timing to prevent stress on the drivetrain. Then once your moving, torque management pulls a crap load of timing during the shifts for the same reason. Get a custom tune and you'll be roasting tires from a dead stop, maybe.
    99 Silverado ECSB 4X4, LQ4, Patriot Stg. 2 243's w/ 59cc chambers, TR224-112, Pacesetter LT's, Nelson tune, FLT Lvl 5.5, PI 3400, UD pulley, 160* t-stat, E-fans, 6'' Fabtech lift, 3'' body lift, 37'' XTerrains, 4.56's, 4'' shackle flip 13.3 @ 99mph on 37's or 13.0 @ 101mph on 31's

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    Re: 2005 Silverado 1500 5.3L V8 Z71 slow acceleration problem

    The problem is that since you don't have a specific code it could be so many things... When the plugs were changed last were they the correct gap? Were they over tighten thus causing the gap to be effected? Your fuel filter is in the pump so you can't change that unless you change the pump. You can check for vacum leaks, MAF could be clean, a hole in the exhaust. There are just so many things that can effect power.

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    Re: 2005 Silverado 1500 5.3L V8 Z71 slow acceleration problem

    im haven the same prob with mine. i think it may be the knock sensor that is doing it i can undo my ground from the battery for about 10 min and reset every thing and it runs half way desent again but then when it throws the knock sensor code up again its back to the same problem

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    Re: 2005 Silverado 1500 5.3L V8 Z71 slow acceleration problem

    2005 don't have fuel filters. Unless your going to drop the tank.
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    Re: 2005 Silverado 1500 5.3L V8 Z71 slow acceleration problem

    I am without a doubt 7 million percent sure your problem is the knock sensors.. I've read that When they are grounded out by water that it tricks the engine into believing you obviously have an engine knock retards the timing and kills all performance to protect and preserve the engine. Look up my older posts when I first joined (I joined and my first post was this exact problem with the same kknock sensor code p0332). It took me 3 weeks of driving for the water to evaporate off the sensors and the code to dissappear. The minute I crunk the engine up and realized I had no check engine light, I punched it and chirped the tires and it took offf!!!!
    This is a thread I had on the chevrolet forum and was toying with the idea of a custom tune, programmer, or chip (I got a blackbear 93 tune and WOWOWW) also trying to figure out why my truck was accelerating so slow. Just read it. I never posted back but the knock sensor code went away and its runnin smooove again

    Anyway sorry so long but just dont want you buying un-needed parts.. read this and good luck http://chevroletforum.com/forum/silv...p-43052/page2/

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    Re: 2005 Silverado 1500 5.3L V8 Z71 slow acceleration problem

    Also, Our trucks also have an "abuse mode" so thats the reason when you come off the throttle it feels like it gains some power.. when you stab the gas to the floor your pcm tells your truck to ease up (gm did this garbage to ensure a longer lasting drivetrain and less warranty work) send it to justin at blackbear performance and have him remove the torque management and all that garbage and it will be a new truck.. Trust me I just got my pcm 2 days ago. My gas mileage is better and it screams when I punch it now to.

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    Re: 2005 Silverado 1500 5.3L V8 Z71 slow acceleration problem

    Alright guys, sorry I'm just now replying. Thanks for all the replies by the way.

    I'd love to send my pcm to Justin, have every since I first got the truck. Just haven't had a chance to since I'm in the truck driving everyday and don't have a backup truck. When I get a chance to, might in the morning at school since my main instructor won't be there, take my intake off and see if it's still wet around my knock sensor. Also gonna go across the building to the welding shop and get one of my exhaust brackets welded back on the pipe that I noticed broke this morning. While I'm over there I'm gonna check to see if there's any leaks or holes throughout the pipes.

    After I do all that and if the code is still showing and still running like it is, I'm gonna get my uncle to order a sensor since he gets a 15% discount on all the parts through his shop account.

    Stingertrey- which option did you get from Justin? I know the last time I looked, he had the Scan cable option and the tradition tune option.

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    Re: 2005 Silverado 1500 5.3L V8 Z71 slow acceleration problem

    Quote Originally Posted by Stingertrey View Post
    Also, Our trucks also have an "abuse mode" so thats the reason when you come off the throttle it feels like it gains some power.. when you stab the gas to the floor your pcm tells your truck to ease up (gm did this garbage to ensure a longer lasting drivetrain and less warranty work) send it to justin at blackbear performance and have him remove the torque management and all that garbage and it will be a new truck.. Trust me I just got my pcm 2 days ago. My gas mileage is better and it screams when I punch it now to.
    How can you tell your mileage is better with only 2 days of driving?


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    Re: 2005 Silverado 1500 5.3L V8 Z71 slow acceleration problem

    I avg'd 18.7 mpg on the way to work this nothing runnin a tick above 70, before when I would reach 70 gas mileage started to go out the window.. Running 55 im over 20-

    Chevcamo-If you decide to do the job I have a set of fel-pro intake gaskets brand new and ill ship them to you cheaper than your uncle can buy them if u want. I also just got a standard mail order tune since my truck isnt far from stock. I have plabs to add lt headers and a cam.. Then I will pay the difference and get the scan cable tune to dial it in. Also the check engine lightt and that code will clear itself when the water evapoorates. If I were taking the time to take the intake off and look I would go ahead and replace them both along with intake gaskets just so its outta sight outta mind ya know

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    Re: 2005 Silverado 1500 5.3L V8 Z71 slow acceleration problem

    I want my sig as big as yours black20.. How!?

    Blackbear 93 Tune - Magnaflow Dumped - Volant cold air intake

 

 

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