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  1. #1

    Default 03 z71 issues help asap please

    ok i have a 2003 z71 silverado its got the 5.3l in it with 4l603 transmission.
    ive been having issues for quite sometime now with it losing rpms and dying at ide speeds.
    such as when im comming to a stop light or sign or go to park in a parking lot.
    the tach will drop and the truck will fall on its nose an dye.

    ive done as suggested by mecahanics and the chevy house
    cleaned throttle body and MAF and the air intake filter.
    changed plugs and plug wires changed the fuel filter.

    and this problem still occurs ive heard it could be the drive by wire throttle body.
    or could be a leak in the intake gasket
    now ive priced a gasket and its about 70$ and i have a chiltons book.
    but is there a way i could test for this without a smoke machiene or ?

    could someone help with some issues here?

  2. #2


    Welcome to the club!! Is your check engine light on? If it is have the trouble code read and that may lead to your issue. If its not on then I would think that it would not be your intake gasket as a manifold absolute pressure (map) sensor should trigger the CEL because of inconsistant readings. Good luck and we hope to see some pics of your truck!!

    2011 Silverado CrewCab 5.3L*Ram Air Look Cowl Induction Reflexxion Hood*6" Pro Comp Lift*Flowmaster Dual exhaust*Perfect Launch Rear Diff. Cover*Led Smoke Taillights*L.E.D.Smoke 3rd Brakelight*60" L.E.D. Tailgate Bar*Rearview Mirror Reverse Camera and Sensors*Smoke Headlight Covers*Front Bumper Grill Insert*Deezee Black Alum. Diamond Rail covers*20" Ultra Motorsports Rims wrapped with 35.5"B.F. Goodrich Tires*Inchannel Raingaurds*CAI*Bullydog GT Tuner*Alpine Amp*Boss 6x9's*Boston Acoustic Subs*Terrantula Tweeters*Custom Sub box*Red Led Interior Accents*5% Ultimacool duo tint rear window and doors, 20% front doors*Custom Vinyl Graphics*Demolded*Debadged*Painted drums and calipers*
    Future Mods Include: Custom Interior Hydrographics, Electronic Rollup Toneau Cover, 4.56 Gears, Painted rear bumper

  3. #3


    check engine lite has been on since ive got the truck and only codes it shows are the o2 sensors.
    it has headers all people ive spoken to about that says theh eaders are prob why check engine lite is on.

    thats the only code it has ever showed

    hehe my truck is ugly has to many issues for pics kinda embarrased of it

  4. #4


    Fuel pump?? old 03 silverado had a fuel pump go out at 120k and when i took it out to replace it,it already had a junkyard fuel pump in it...

    2009 Chevrolet Silverado 1500 LT Z71 Crew Cab "All-Star Edition"

    Line-X'd Bed
    Line-X'd Custom Brush Guard(Heavy Duty)
    5.3L Flex Fuel
    275/65R18 Toyo Open Country AT2's
    2" Rough Country Leveling Kit(want to get the 2.5 RC kit)
    EGR In-Channel Vent Visors
    Exterior PLUS Package
    Interior PLUS Package
    K&N Drop-In Air Filter
    Cat-Back Dual Exhaust
    Black Bowties
    Diablo Sport Predator(AFM Disabled)
    Towing Mirrors
    Next Planned Mods
    Blacked out Tail Lights
    Aftermarket Rims

  5. #5


    i seem to be getting 58lbs to the fuel rail from the pump

  6. #6


    I would guess the its not getting enough fuel at idle... Maybe MAF sensor, fuel filter or fuel pump.
    I'm sure others will chime in.

    And yes headers will cause lean codes to trigger on bank1 and 2... Mine did hense my purchase of the trinity and custom tune from diablew tune.
    2009 Chevy Silverado 2500HDLT 6.0L w/ Towing Package, Dick Cepek GM8 Rims, Dick Cepek FC II 33X11.50R17,RKSport Ram-Air Hood(Functional), Lazer Lite Aluminum Tonneau Cover, Road Armor Stealth Bumper, PIAA Lighting, Diablo Trinity Tuner, Diablew Custom Tune, BullyDog Cold Air Intake, American Racing Headers w/highflow cats, Corsa Performance Sport Exhaust, Custom Striping, Black Bowties front and rear, Fuel Grille Inserts, Recon Headlights, Readylift Shocks, Readylift Upper Contol Arms, 2" Blocks in the Rear..

    Future Plans: HD Tie Rods, Under hood upgrades, Crower Camshaft and possibly electric fans.

  7. #7


    I had the same stalling issue with an 03 yukon xl. When I bought it, it would bog down and stall at lights. turned out to be a bad battery and alt
    Last edited by Pikey; 10-12-2012 at 11:52 PM.

    1995 Silverado 4x4
    6" BDS Suspension Lift-3" Body Lift-Add A Leaf in rear -Trailmaster SSV Shocks-Duel Steering Stabilizer Kit -AirAid Cold air intake-
    4.56 Gears with Detroit Auburn Locker-Pro-Comp Traction Bars with duel shocks-Aluminum Skid Plate Kit-38.5" x 16.5" Mickey Thompson Baja Claws-Constant Dropping fuel gauge

    2005 Yukon XL Jet Power Programmer, Bilstein Shocks, Bilstein rear springs, Helwig Anti-sway bars, EGR Window Visors, EGR Hood Shield, Denali Headlights, Headlight harness upgrade, GE NightHawk Bulbs, White Night Rear lighting system, Russell Braided SS brake lines, PowerStop Brake pads, PowerStop cross drilled and Slotted Rotors,
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

  8. #8


    ive replaced the fuel filter checked hte pressure of the fuel pump appears ive got 58lbs to the rail.

  9. #9


    Quote Originally Posted by CD82 View Post
    ive replaced the fuel filter checked hte pressure of the fuel pump appears ive got 58lbs to the rail.
    I understand that, as you posted that information in a previous post. I was just stating that I had a 03 truck that did the exact same thing. It turned out to be the battery. If you know that you have bad 02 sensors then you need to fix that or the computer will give the wrong commands for fuel, spark advance and spark retard. The bad O2 sensors can destroy your MPG also. If you have duel exhaust and the sensors are not installed then you need to install o2 replicators.

  10. #10


    my mpg is great actiualy 15 mpg in town i think that is decent

    i will get the alt and battery checked the battery seems to hold a very good charge
    from what the guage says in the dash but i have them chekced to make sure

    battery is less than a year of it it turns out to be that then i can get it replaced.

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