cut off stock muffler 1500 miles later very ruff

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by gbal4, Apr 20, 2007.

  1. gbal4

    gbal4 New Member

    I cut off my stock muffler and 1500 miles later truck has a very rough idle almost like I put in bad gas but that is not the case what could be the cause of this??
    I have a 2000 silverado ext 283 V8 just turn 100,000 miles :eek:
  2. unplugged

    unplugged Epic Member 5+ Years 1000 Posts

    Less is not always mo' better

    I would guess that the PCM (powertrain control module) can't compensate for the decreased back pressure. Are you getting any OBDII codes? I believe your 2000 Silverado uses a multistage EGR valve that works in part by monitoring the exhaust back pressure. It could be the source of the problem. You might also want to try reseting the PCM by disconnecting the battery to clear the memory and have it re-scan the trucks new operating characteristics.

    Wells Mfg has an article about the new digital EGR valves

    In the 1990’s, electronic (digital) EGR valves
    began to replace vacuum-actuated EGR valves
    because they can respond much faster to changes
    in operating conditions and work independent
    of intake vacuum. Several different types
    are used:
    • Single-stage (A single solenoid is used to open
    the exhaust passageway valve). The computer
    monitors various sensor inputs to determine
    when EGR is needed, then cycles the EGR valve
    solenoid on and off to control the amount of
    exhaust gas recirculation.
    • Multi-stage (Used on various late-model
    General Motors applications, this type has two
    or three solenoids that open separate exhaust
    passageway valves. See Figure B.) With this
    setup, the computer uses a step strategy to
    increase EGR in stages. If only a little EGR is
    needed, one solenoid is energized. As more EGR
    is needed, the second and third solenoids are
    energized. On the three-solenoid applications,
    up to seven different combinations may be used
    to control EGR flow.
  3. gbal4

    gbal4 New Member

    I`m not getting any codes at least I don`t think I am how do I find this out??
  4. unplugged

    unplugged Epic Member 5+ Years 1000 Posts

    Is your check engine or service engine soon light on? Many parts stores like AutoZone will loan you a code reader if you don't have one.

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