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96 Vortec stumble/miss after changing intake gasket UPDATE PROBLEM SOLVED

Discussion in '1992-Present Chevy & GMC models' started by MOABDADC22, Feb 27, 2003.

  1. MOABDADC22

    MOABDADC22 1/2 ton status

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    I posted this in the garage too, but figured maybe you guys/gals could help.

    I just got done changing the intake gasket /forums/images/graemlins/angryfire.gif /forums/images/graemlins/angryfire.gif on my 96 Tahoe (5.7 Vortech.) Now it has a very noticible miss. The "Check Engine" light flashes on/off at a steady rate.

    All hoses/wires are in the correct spot. I have sprayed the intake with carb cleaner to check for a leak with none found.

    I did get the distributor 180 degrees off on the first attempt (DUH....) but pulled it and put it in the correct spot. I am pretty sure that the base timing is set right at 0 degrees. Is this correct?? I guess I could go fire it up and turn the distributor a little and see if that cures it. If it does.......how do I clear the trouble codes??

    Any help would be greatly appreciated. /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif
     
  2. MOABDADC22

    MOABDADC22 1/2 ton status

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    Re: 96 Vortec stumble/miss after changing intake gasket HELP

    I forgot to add that the engine runs pefectly smooth for about the first 2-3 seconds after I start it, then it develops the miss.

    It ran like a top before I changed the gasket.
     
  3. heavy4x4

    heavy4x4 1/2 ton status

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    Re: 96 Vortec stumble/miss after changing intake gasket HELP

    With the engine running - grab some of your spark plug wires and move them around (not disconnect them, just move them around) - see if that does anything. You may have some wires laying on eachother and the charge going through one wire get's crossed with/taken by another wire. /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif Worth a try. Also, re-check the placement of the sparkplug wires on the cap. If two of them are mixed up, you'll get miss-fire like you described. I know you said you have them right - but just check again *trust me* /forums/images/graemlins/smirk.gif
     
  4. MOABDADC22

    MOABDADC22 1/2 ton status

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    Re: 96 Vortec stumble/miss after changing intake gasket HELP

    OK, I scanned the codes with an OBDII and got P0102 (Mass Air Flow sensor Circuit Low Frequency) and P0304 (Misfire on #4 cylinder). soooooo....I am thinking that the # 4 intake gasket area did not seal/seat good enough and that is causing the MAF to detect air leaking in and then causing the #4 to misfire??

    Am I way off base or what??? I will probably buy another gasket and start over. (At least now I know that I can change the gasket in under three hours) /forums/images/graemlins/thumb.gif

    Thanks for the replies /forums/images/graemlins/deal.gif /forums/images/graemlins/deal.gif.......keep them coming since I will read them again in the morning. /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif
     
  5. ntaj*ep

    ntaj*ep 1/2 ton status

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    Re: 96 Vortec stumble/miss after changing intake gasket HELP

    I'm starting off here ignorant to your skill level so bear with me. The Vortec engines use a SPFI(sequental port fuel injection) system which is diffrent than other GM style systems in that your injectors are firing with the firing order. The other systems fire a bank of injectors at a time not just one. Anyhow your codes tell me a few things. I would start off with the basic(easiest) stuff first. Make sure your ign. wires and injector wires are all connected to the correct cylinder. I think your good here, but check it anyway. One word of advice, do not use carb cleaner on a running feedback fuel injected motor, use intake air fuel injection safe stuff. /forums/images/graemlins/thumb.gif
    With the style of gasket the Vortecs use I'm not surprised you couldn't get a change, however I don't know how bad the miss is either /forums/images/graemlins/eek.gif. The torque on the intake bolts if I'm not mistaken is like 15-20 ft-lbs. Not alot to get them tight, so keep this in mind as well. When/if you remove the intake again look for hair line cracks in the plastic (just to let you know your doing a good job, and found it) /forums/images/graemlins/thumb.gif
    Hope any or all of that helps you. /forums/images/graemlins/thumb.gif
     
  6. finnd

    finnd Registered Member

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    Re: 96 Vortec stumble/miss after changing intake gasket HELP

    verify all the fuel injectors are hooked up correctly and working. You may get a gassy smell if one is dumping. Check the plug for that cylinder as well to see if it is getting really fouled.
     
  7. MOABDADC22

    MOABDADC22 1/2 ton status

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    Re: 96 Vortec stumble/miss after changing intake gasket HELP

    Ok, I was right....the intake gasket was not sealing on the #4. I think the gasket slipped down and out of alignment when I lowered the intake. All fixed now.

    How do I clear the trouble codes now and get the check engine light off?
     
  8. 90K5

    90K5 1/2 ton status

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    Re: 96 Vortec stumble/miss after changing intake gasket HELP

    disconnect the battery
     
  9. 89K1500Chevy

    89K1500Chevy 1/2 ton status

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    Re: 96 Vortec stumble/miss after changing intake gasket HELP

    Its an OB2 com so youll have to go hook it up to a scaner to clear the troble codes if it were OB1 then yes the battery trick could work but its different with OB2
     

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