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Missfire Help ~ 2007 Chevy Silverado

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by dantheman1, Jul 28, 2013.

  1. dantheman1

    dantheman1 New Member

    Newb Here! 07 NBS silverado, Ive got a miss on number 2 (p302 code). What Ive done so far: changed the plugs, wires, all the coils, checked all the injectors they have a strong pulse, cleaned MAF sensor. I really don't know where else to go from here cause now the 'stabilitrak needs to be serviced' light comes on to. The dealer told me if I fix the 'miss' it will probably correct the stabilitrak error (sense the tcm and pcm work together he said). If I disconnect the battery and reset the computer the check engine light goes off and I may not see it come on again for another month. Then out of the blue it just comes on again. Question is, could my computer be going bad? Would an O2 sensor cause the miss? Really don't think theres any vacuum leaks.
     
  2. ChevyBoy2009

    ChevyBoy2009 Rockstar 4 Years 500 Posts

    Welcome to GMTC!...make sure all connections are tight and are not dirty...when my neighbor changed his plugs and wires he had accidently switched 2 wires around and ran it that way for a couple months...got terrible mpg and was chugging...took me 2 secs to figure his issue out :great:...also are you running an oiled filter?...if so check your MAF sensor,could be alittle gunky!
     
  3. j cat

    j cat Rockstar 4 Years 1000 Posts

    the plug wires should be checked for proper resistance. compare the old to new. the plugs should be ac delco iridium. also check the fuel pressure. make sure you keep fuel level above 1/4 tank at all times.
     
  4. ChevyBoy2009

    ChevyBoy2009 Rockstar 4 Years 500 Posts

    OEM Ac Delco is the way to go...dont use any other plug than that!...check gap on them also
     
  5. dantheman1

    dantheman1 New Member

    Everything I put back in was OEM stuff..plugs an all. I have not checked fuel pressure. As far as connections can somebody tell exactly which ones and where they are located to check? The dealer checked my plugs and he said all that was good an I know they are to. Well when the engine is cold as soon as you push the gas there is a little hesitation. If the injectors are good..its gotta be fuel pressure. Keep the info coming!!!
     
  6. ChevyBoy2009

    ChevyBoy2009 Rockstar 4 Years 500 Posts

    Have you checked and cleaned your MAF sensor?...these newer vehicles can be very picky...whats your mpg now?
     
  7. RayVoy

    RayVoy Well-Known Member 2 Years 1000 Posts

    You should have been on here a few days earlier, unless you picked up those parts for cheap, you spent a lot of money without a fix. Keep the coils for spares.

    After changing everything you still have a mis-fire. Have you had the mis-fire code re-read? Is it still cylinder #2?

    Things that cause mis-fires: spark (plugs, coils and connections), vacuum leaks (intake manifold, throttle body, hoses), compression.
     
  8. forum1015

    forum1015 New Member

    Do not discount vacuum leaks around the intake manifold. Dexcool reacts badly with the gasket material degrading the seal from manifold to head. If all else fails, pull intake and replace gasket with upgraded Felpro's. Around $75. I got wise after my 2nd experience with this problem. Also, it might be a good idea to replace the knock sensors while your in there.
     

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