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  1. #1

    Default misfire question...

    just another lovely misfire question for you guys...

    Ive been dealing with misfires for over 2 years now, they just never stop, but anyway ive had a steady (random misfire) at idle for over a year now, and it is easily detectable to the human ear and quick "bump" in the truck when it happens obviously.... only thing is it never throws a code! itll misfire all day while idling and never throw a code? can anyone offer insight as to why my engine does not throw a code when having these misfires? it has thrown codes before for misifiring when i needed to replace my distributor and such, but not for this...
    2000 Chevrolet Silverado

    Powertrain:
    4.3L V6, 4L60E, 2WD, Single Cab
    Performance:
    Airaid CAI
    Poweraid TB Spacer
    Flowmaster 10-series exhaust (dumped)
    BLACKBEAR TUNED!!!
    Edge CS insight monitor
    4.10 gears
    Limited-slip differential
    LS-1 Dual Electric fans
    Corvette tranny servo swap

    Audio:
    Head Unit: Alpine
    Speakers: Alpine SPR-60C 6.5" component set, 4X6 Infinity Kappas
    Subs: 2-12" Kicker CVT's
    Amps: Alpine-M1000 (subs), Alpine MRX-F65 (Speakers)


    Tires/Wheels:
    305/70R16 NITTO Terra Grapplers
    16" PROCOMP 7089's
    Suspension:
    2" leveling kit
    3" Fabtech Spindle Lift Kit
    Front/Rear-Bilstein 5100 shocks

    Lighting:
    FRONT
    35W HID Low Beams
    RECON LED smoked roof cab lights
    REAR
    HELLA LED taillights and 3rd brakelight
    HELLA FF-75 Aux. Reverse Lamps
    RIGID dually D2, flush mount, wide beam
    Accessories:
    Hawk HPS Brake pads
    Russell braided steel brake lines
    Powerstop-red powdercoated brake calipers
    Powerslot Cryo brake rotors
    EGR in-channel window visors

  2. #2
    Sr. Apprentice
    Join Date
    Nov 2013
    Location
    Alliance,Ohio
    Posts
    64

    Default

    My first guess would be burnt out cluster bulb! But as with mis-fires like you I have been dealing with the same issue for about the same amount of time and without the drawnout troubleshooting process it could be numerous things. Have you had it on a scanner lately?
    1998 1500 w/t short bed 4.3

  3. #3

    Default

    Quote Originally Posted by fugitive View Post
    My first guess would be burnt out cluster bulb! But as with mis-fires like you I have been dealing with the same issue for about the same amount of time and without the drawnout troubleshooting process it could be numerous things. Have you had it on a scanner lately?
    no its not a burnt cluster bulb, that works just fine, I actually have an Edge CS insight monitor and can read and clear DTC's on the fly, prior I would check with my hypertech programmer, even while its misfiring and everything it never throws a code, last time i had it checked was when Justin at blackbear performance told me it was probably due to my CMP retard being off -12 degrees or something, which i did take to a reputable shop that claims they fixed that, though it never made a difference, since then ive really just given up and dealt with it for now

  4. #4
    Sr. Apprentice
    Join Date
    Nov 2013
    Location
    Alliance,Ohio
    Posts
    64

    Default

    One thing that is kinda outside the box you could try is check to make sure the vent holes on the bottom of your distributor are'nt blocked preventing the ozone gasses from escaping that are created during the numerous arcing cycles of the rotor to the cap those gasses are what cause the discolor/oxidation on the contacts. It's worth a shot. Good luck I know it didn't help mine when I removed the screens but it may help yours I'm still fighting mine but the light keeps returning I have been leaning toward a lean fuel condition underload?

  5. #5

    Default

    Are you sure that it is a mis-fire and not a rough idle? I am pretty sure that a mis-fire would throw a code. I think over time I have gotten to know you and I am sure that you have already done some of the things I am going to suggest. I would check your IAC. maybe pull it out and clean the tip off. My 95 had a rough idle with no codes, I finally tested the iac and found it to be at the highend of the recommended spec. I changed it and the idle smoothed out almost instantly. Also, you may want to pull the egr valve and give it a good cleaning (if equipped, my 03 and 05 do not have them.) it will cost you $4 for the gasket. Also, I am sure that you have done it, but clean the MAF and throttle body well. My 02 developed a unstable idle, I ran some sea foam thru the brake booster vac line, let it sit for 20 minutes and started it up. The idle smoothed out. I am just making suggestions here. I really think that a mis-fire would be throwing a code. I am thinking it is a rough idle caused by something else.

    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, http://www.gmtruckclub.com/forum/sho...5-GMC-Yukon-XL
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

  6. #6

    Default

    Quote Originally Posted by Pikey View Post
    Are you sure that it is a mis-fire and not a rough idle? I am pretty sure that a mis-fire would throw a code. I think over time I have gotten to know you and I am sure that you have already done some of the things I am going to suggest. I would check your IAC. maybe pull it out and clean the tip off. My 95 had a rough idle with no codes, I finally tested the iac and found it to be at the highend of the recommended spec. I changed it and the idle smoothed out almost instantly. Also, you may want to pull the egr valve and give it a good cleaning (if equipped, my 03 and 05 do not have them.) it will cost you $4 for the gasket. Also, I am sure that you have done it, but clean the MAF and throttle body well. My 02 developed a unstable idle, I ran some sea foam thru the brake booster vac line, let it sit for 20 minutes and started it up. The idle smoothed out. I am just making suggestions here. I really think that a mis-fire would be throwing a code. I am thinking it is a rough idle caused by something else.
    done everything you said except the IAC and EGR, i should check those (on my third distributor lol) but i know its a misfire, because when i was sitting there with Justin doing my retune, he had his laptop hooked up and was showing me at idle that i was having multiple random misfires thats when he suggested the CMP retard. I know it is misfiring for sure....

    but in the end isnt a "rough idle" caused by misfiring???

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