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  1. #1

    Default I know what it isn't

    Still having acceleration problems and rough start. Idle is a little rough. New fuel phinp, filter, clean K & N, new electric components. I think I will change all the oxygen sensors, Anyone have O2 sensor problems? I also still have gurgle sound behind dash when i accelerate. Seperate issue prob.

  2. #2


    You might have old/worn out/lazy O2 sensors, but if the problem is there when the engine is started cold (after sitting all night) it isn't the O2 sensors.

    When the engine is cold, the O2 sensors are not used, The sensors need to be hot and the exhaust gases need to be hot before the O2 sensors work properly.

    And if the sensors were bad when the engine gets up to operating temps, the PCM would throw codes and light the Check Engine Light.

    Does "new electric components" mean spark related things.

    Vehicle info would help me here.

    '09 Avalanche LTZ - Black
    '05 Envoy XL (sold)

  3. #3


    97 jimmy. New spark plugs, wires, ignition coil, dist. rotor and cap. New battery. Original sensors, 220000 MI

  4. #4


    If that was my old Envoy, I would say the throttle body was dirty. If you had a carburetor, I would say the carb was dirty. I don't know about the throttle body on your truck, it has fuel injection as part of the throttle body, maybe the injector is dirty or worn.

  5. #5


    Just cleaned my throttle body. My next idea was also the injectors. I do use Lucas injector cleaner every oil change.

  6. #6


    Check the fuel pressure with a gauge.. Even though its new they can be low on pressure and defective. I went through this with a 99 jimmy I had. Mine required 65 psi to start and 55 to run..put a pump in and same problem. put a gauge on it and the pressure was 48 psi.. returned it for another and waalaaa.. purred like a kitten. you can rent the gauges basically for free from advanced or autozone.
    They are a pain to pull out of the tank. but Ive done it 5 times so I had it down to about a half hour R&R.

    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

  7. #7


    Overdue for a cleaning
    Attached Thumbnails Attached Thumbnails uploadfromtaptalk1394156923880.jpg   uploadfromtaptalk1394157040642.jpg  

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  9. #8


    Thats not helping any. Good find.. let us know if that was the issue.

  10. #9
    Jr. Engineer
    Join Date
    Oct 2013
    weedsport, NY


    That much crud on the bottom of the TBI unit? I'm thinking the EGR valve is stuck open with some crud! Jimmy I had was the same way! Carbon would hold the valve open just a little and the truck run like crap!

  11. #10


    I think i will take the cheap fuel pump back and try an OEM or an american made. Then, get into the recirc. Valve. Haven't heard that problem before thanks i will be replacing that.

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