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GM 4.3 TBI question

Discussion in 'Early CJ5 and CJ6 Tech' started by w3srl, Nov 26, 2006.

  1. Nov 26, 2006
    w3srl

    w3srl All-around swell dude Staff Member

    Port Orange, FL
    Joined:
    Nov 6, 2002
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    4,275
    Not completey Jeep-related, but I know a lot of guys run the 4.3 in their rigs.

    Does anybody know what would cause a late-model 4.3 with TBI to keep gunking up the EGR valve? I have a '94 GMC Jimmy at work that spends more time in the shop than on the road because it keeps plugging up the EGR circuit with carbon. The computer doesn't throw any codes until it starts running really crappy, and it's time to pull the EGR valve off and clean/replace it again. I'm to the point of having to do this about every two weeks.

    Idears fellas?
     
    w3srl, Nov 26, 2006
    #1
  2. Nov 26, 2006
    CJ-X

    CJ-X Member

    Ohio
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    Aug 6, 2006
    Messages:
    816
    It is your exhaust gases, so incomplete combustion? Running too rich? And I guess that lots of problems could cause that. I would think that any good GM tech would blurt some possible answers right out. If they can't tell you, you might want to stop going there.
     
    CJ-X, Nov 26, 2006
    #2
  3. Nov 26, 2006
    camionetta

    camionetta Assistant Junior Member

    Tempe, AZ
    Joined:
    Apr 26, 2006
    Messages:
    26
    I have no idea if this helps, but GM issued recall bulletin No. 96067A in 1997 with the title Linear EGR System Sticking Open/Closed. I think this covered at least some 4.3L enginesand I believe they upgraded the memory chip to fix this. On the other hand, this may be all nonsense.

    Kevin
     
    camionetta, Nov 26, 2006
    #3
  4. Nov 27, 2006
    jpflat2a

    jpflat2a what's that noise?

    Hermosa, SD
    Joined:
    Jul 30, 2003
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    8,524
    from a mechanical aspect, I would suspect the engine is using/burning oil, causing the excessive carbon buildup.
    does it use excessive amount of oil ?
     
    jpflat2a, Nov 27, 2006
    #4
  5. Nov 27, 2006
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
    Joined:
    Sep 23, 2002
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    12,529
    X2. I'd suggest a thorough evaluation including a compression and leak down check to establish basic engine condition before going much further. If basic engine is in poor condition the rest is tail-chasing. Nickmil
     
    nickmil, Nov 27, 2006
    #5
  6. Nov 27, 2006
    w3srl

    w3srl All-around swell dude Staff Member

    Port Orange, FL
    Joined:
    Nov 6, 2002
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    4,275
    Sorry guys, it has about 80k on the ticker and it doesn't use a drop of earl in between changes. My fleet mgt. program has the earl/lube/filter done on most of our stable at 180 days or 3k miles.

    The thing that really has my boxers in a wad is that the stealership that serviced this thing has been resetting the computer and putting an EGR valve in it like clockwork for almost 8 years. This was a police vehicle before being handed down to the fire guys, and it is really beat. (To say that our cops aren't very particular on maintenance is being VERY charitible.) :rofl:

    To add insult to injury, it's replacement was cut out of the line-item budget this year. I've got to keep this POS Jimmy running for another year and about 10k miles. At this rate that is 4 more EGR valves, give or take $350 bux...
     
    w3srl, Nov 27, 2006
    #6
  7. Nov 27, 2006
    coby61

    coby61 Stupidiotic Member

    Prunedale CA
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    Mar 10, 2004
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    388
    Has the temp sensor for the TBI been changed? This would not trip any codes but will cause a slight rich condition which over time could plug the EGR and not foul the plugs. My .02
     
    coby61, Nov 27, 2006
    #7
  8. Nov 27, 2006
    w3srl

    w3srl All-around swell dude Staff Member

    Port Orange, FL
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    Hmmm, gonna have to check the records and see if it has been changed. Thanks Coby!

    BTW- The paper maintenance file on this POS looks like a metro phonebook... :rofl: It was all on paper prior to 2001. :mad:
     
    w3srl, Nov 27, 2006
    #8
  9. Dec 15, 2006
    Jack Frost

    Jack Frost Member

    Mineral, VA
    Joined:
    Nov 28, 2006
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    114
    i know this thread is basically dead, but what about the oxygen sensor?
     
    Jack Frost, Dec 15, 2006
    #9
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