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Thread: HELP! Constant rough idle.. 2003 6.0L

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  1. #1
    Join Date
    Oct 2007
    Location
    Canton, Ohio
    Posts
    24

    HELP! Constant rough idle.. 2003 6.0L

    The trucks got 113k on it, i've replaced the plugs (AC irid plugs), Wires (crane 25ohm firewire), knock sensors, intake gasket, and cleaned the throttle body.. I cleaned MAF with QC electric cleaner also..

    The idle stays perfectly still as far as rpms go but you feel it missing the entire time.. like someone is lightly shaking the truck the entire time its at idle. WHAT GIVES! its driving me insane and i don't have a scanner, no one around me has a scanner for these year trucks..

    Do the plugs suck? Do i have bad coil(S)... Someone said something about EGR.. ANYTHING SOMETHING!!! lol.. it makes the truck seem like such a peice of $hit when anyone is in it.

    Also the throttle is so touchy that hitting bumps the throttle spikes easily and its a mess.. Throttle seems way to touchy, then if you do floor it the thing sounds like its bogged down.. If you hit the gas 50% or so it pulls ten times harder than full throttle.

    Thanks! I'm hoping to hear some options for tomorrow so while i've got the day off i can start looking over it.
    2003 Silverado 2500 6.0L/New 4L80E HD2 Kit, Bilsteins, Reg Cab LB 2WD.

    1994 S10 - McCoy/Hitech Built forged/cryo 4 bolt ty bottom end, CAMS,inc vortec heads full rollers etc, PT60 Turbo, bar & plate A2A, meth inj, Custom MPFI intake and plenum #65 lowz inj, LSX TB, MS2 PCB 3.0 EFI, 4.3L 43K,8.5 posi & disc 3.42, C5 vette brakes

    1994 Jeep Yj, fresh frame off build, 4.0L banks header, B&M short throw, BDS & BILSTEIN susp., waggy D44's w/flat top knuckles, PM's crossover, 1ton hydroboost, PSC powersteering pump, GM 2500 front disc setup, GM front 1500 Disc on rear, 4.56's & ARB's, 35 MTR's

  2. #2
    Join Date
    Mar 2003
    Location
    San Marcos Texas
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    4,393
    See if you can borrow someone's MAF and try it. I bet yours is bad.
    2006 Superior Blue Trailblazer SS AWD, Stock as a rock

    Sold: 2002 GMC Sportside Denali front end with a 2002 LS1, FLT level 5, Yank 2600, Trick Turbo, T76, Nelson intercooler, 60LB injectors, Warbro fuel pump, Eaton locker, Magnaflow, 3.42, Nelson Performance Tuning (speed density).

    Sold: 1981 GMC LB RC 1500 2002 4.8L 4L60E 12 bolt 3.73 Richmond Lock Right AC PS Nelson Performance tuning

  3. #3
    Join Date
    Oct 2007
    Location
    Canton, Ohio
    Posts
    24
    you think its the MAF, what if i disconnect the MAF does these computers fail over to speed desity and that would let me see if it idles smooth
    2003 Silverado 2500 6.0L/New 4L80E HD2 Kit, Bilsteins, Reg Cab LB 2WD.

    1994 S10 - McCoy/Hitech Built forged/cryo 4 bolt ty bottom end, CAMS,inc vortec heads full rollers etc, PT60 Turbo, bar & plate A2A, meth inj, Custom MPFI intake and plenum #65 lowz inj, LSX TB, MS2 PCB 3.0 EFI, 4.3L 43K,8.5 posi & disc 3.42, C5 vette brakes

    1994 Jeep Yj, fresh frame off build, 4.0L banks header, B&M short throw, BDS & BILSTEIN susp., waggy D44's w/flat top knuckles, PM's crossover, 1ton hydroboost, PSC powersteering pump, GM 2500 front disc setup, GM front 1500 Disc on rear, 4.56's & ARB's, 35 MTR's

  4. #4
    Join Date
    Aug 2007
    Location
    Castro Valley, CA
    Posts
    235
    fuel filter... just a guess... but if you go WOT, and it bogs down, could be the full filter being clogged... to if it's idling rough, might not be getting enough fuel..
    2004 4.8l 6 speed manual 2wd
    Looks: 22" foose rims with Fierce tires, SS front bumper, SS Front Grill, 2/3 lowering kit.
    Performance: Volant Intake, 3" exaust with Spintech muffler, Pacesetter LT's with Y pipe, TR cam 220/220 .551 112 lsa, T56 Tranny with the Keisler short Shift kit and LS7 Clutch, Quicktime Scatter Shield, ASP Underdrive pulley kit, Dyno tune by Rick at Synergy Motorsports
    Soon to Come:Eaton locker, Electric Fans..Does it ever End?

  5. #5
    Join Date
    Mar 2003
    Location
    San Marcos Texas
    Posts
    4,393
    Quote Originally Posted by turbochevy View Post
    you think its the MAF, what if i disconnect the MAF does these computers fail over to speed desity and that would let me see if it idles smooth
    I've never tried it on one, but it might run differently enough to tell if that is the problem or not. It wouldn't hurt to try it. It will set two codes, MAF and IAT.
    2006 Superior Blue Trailblazer SS AWD, Stock as a rock

    Sold: 2002 GMC Sportside Denali front end with a 2002 LS1, FLT level 5, Yank 2600, Trick Turbo, T76, Nelson intercooler, 60LB injectors, Warbro fuel pump, Eaton locker, Magnaflow, 3.42, Nelson Performance Tuning (speed density).

    Sold: 1981 GMC LB RC 1500 2002 4.8L 4L60E 12 bolt 3.73 Richmond Lock Right AC PS Nelson Performance tuning

  6. #6
    Join Date
    Dec 2003
    Location
    Newark, Tx.
    Posts
    1,303
    Have you done a compression check or leak down test. That wont really explain the bogging, but it can the rough idle.
    '92 GMC reg. cab, step side. 7.32@ 92.3. SOLD
    http://videos.streetfire.net/video/d...d700c6401f.htm
    New project: '00 S-10 ext. cab, ZQ8, 370, T-56, daily driver.

  7. #7
    Join Date
    Oct 2007
    Location
    Canton, Ohio
    Posts
    24
    Ya i should do a compression check,.. but i really don't want to know .. Not ready to screw with the internals etc.. still dumping money in other projects and trying to pay off the truck.

    Fuel filter is a really good one.. I'll look and see if i can find somewhere open thanksgiving to pick one up and throw it on.

    Is everyones throttle deadly sensitive or is that somehow related to the rough idle etc..

    I've got a ported throttle body from green6.0 that i'm waiting to put on until i think i've got this idle thing worked out...

    Thanks again everyone
    2003 Silverado 2500 6.0L/New 4L80E HD2 Kit, Bilsteins, Reg Cab LB 2WD.

    1994 S10 - McCoy/Hitech Built forged/cryo 4 bolt ty bottom end, CAMS,inc vortec heads full rollers etc, PT60 Turbo, bar & plate A2A, meth inj, Custom MPFI intake and plenum #65 lowz inj, LSX TB, MS2 PCB 3.0 EFI, 4.3L 43K,8.5 posi & disc 3.42, C5 vette brakes

    1994 Jeep Yj, fresh frame off build, 4.0L banks header, B&M short throw, BDS & BILSTEIN susp., waggy D44's w/flat top knuckles, PM's crossover, 1ton hydroboost, PSC powersteering pump, GM 2500 front disc setup, GM front 1500 Disc on rear, 4.56's & ARB's, 35 MTR's

  8. #8
    Join Date
    Oct 2007
    Location
    Canton, Ohio
    Posts
    24
    How often do you guys change your fuel filters and how long can you go before you notice its messed up? And does walmart sell them lol.. looking like wally world is going to be the only turkey day option for a filter.
    2003 Silverado 2500 6.0L/New 4L80E HD2 Kit, Bilsteins, Reg Cab LB 2WD.

    1994 S10 - McCoy/Hitech Built forged/cryo 4 bolt ty bottom end, CAMS,inc vortec heads full rollers etc, PT60 Turbo, bar & plate A2A, meth inj, Custom MPFI intake and plenum #65 lowz inj, LSX TB, MS2 PCB 3.0 EFI, 4.3L 43K,8.5 posi & disc 3.42, C5 vette brakes

    1994 Jeep Yj, fresh frame off build, 4.0L banks header, B&M short throw, BDS & BILSTEIN susp., waggy D44's w/flat top knuckles, PM's crossover, 1ton hydroboost, PSC powersteering pump, GM 2500 front disc setup, GM front 1500 Disc on rear, 4.56's & ARB's, 35 MTR's

  9. #9
    ff_jeff Guest
    if you need a stock MAF I have one.

  10. #10
    Join Date
    Oct 2007
    Location
    Canton, Ohio
    Posts
    24
    I might need one, how many miles are on yours? My trucks got 113k on it so i'd like to find one low miles or something. what are you thinking for a price.. shoot me a PM if you want. Going to go steal the MAF off another 6L i've got sitting in the shop thats a 03 with 40k on it and see if its helps..i'll let you know.
    2003 Silverado 2500 6.0L/New 4L80E HD2 Kit, Bilsteins, Reg Cab LB 2WD.

    1994 S10 - McCoy/Hitech Built forged/cryo 4 bolt ty bottom end, CAMS,inc vortec heads full rollers etc, PT60 Turbo, bar & plate A2A, meth inj, Custom MPFI intake and plenum #65 lowz inj, LSX TB, MS2 PCB 3.0 EFI, 4.3L 43K,8.5 posi & disc 3.42, C5 vette brakes

    1994 Jeep Yj, fresh frame off build, 4.0L banks header, B&M short throw, BDS & BILSTEIN susp., waggy D44's w/flat top knuckles, PM's crossover, 1ton hydroboost, PSC powersteering pump, GM 2500 front disc setup, GM front 1500 Disc on rear, 4.56's & ARB's, 35 MTR's

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