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89 K5 Help !! Rough Idle and sluggish

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by rocko, Nov 7, 2001.

  1. rocko

    rocko 1/2 ton status

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    My 89 is idling real rough... in park it's fine.. once i put it in Drive and cruise at low speeds 10-40mph it's real rough.. then when I stop at a stop light.. it sounds like it want's to die. Then when I accelerate off the line it's rough until I get up to speed.
    Any idea's? I checked the plug wires and plugs, changed the fuel filter about 1 month ago.. filled the truck up with Super unleaded... nothing helping so far..
    I find this detail strange.. My "service engine soon" light used to come on after 20 minutes of driving.. since this happened it doesn't come on anymore... weird?
    Any suggestions would be greatly appreciated.. I need my truck to commute back and forth to Fort Hood every day... and I have a few day's off coming to get married and fix it. [​IMG]. thanks in advance.

    I haven't failed, I've found 10,000 ways that don't work. www.rocko.rockcrawler.com
     
  2. Rebel88

    Rebel88 1/2 ton status

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    i just fixed this on my 88...i thought it was the O2 sensor so i changed that and it still happened...next i read the codes and it was the egr valve sticking that made it run like [censored] and trip the service engine soon light...try bridging the a and b gaps in the computer hookup thats what i did

    Later

    Have you driven OVER a Ford lately?
     
  3. rocko

    rocko 1/2 ton status

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    Thanks.. I'll give it a try.. I have already replaced the O2 sensor.. but that was a while ago...

    I haven't failed, I've found 10,000 ways that don't work. www.rocko.rockcrawler.com
     
  4. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    It might be worth it to check the EGR valve and make sure the injector spray patterns are correct.

    It also could be an 02 sensor like Rebel said.



    <font color=blue> NEVER FORGET, NEVER FORGIVE, NEVER SURRENDER<font color=blue>
     
  5. CaptCrunch

    CaptCrunch 1/2 ton status

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    My first checks would be injector spray patterns and to see what the resistance is on the injectors. Very easy to do w/ any cheap multimeter.

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
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  6. Dunc03

    Dunc03 1/2 ton status

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    My 86 did the same thing for a while, and it was the egr sticking. My mechanice cleaned out the valve and it stopped doing it. You might even look into getting a egr block off plate. You put it in place of the egr and plug the vacuum hose with somthing like a golf tee or screw. All the egr does is reburn exhaust at above idle rpm, it a pollution reduction item. Affectively all it does is reduce horsepower and cause problems. I blocked it off on mine and it runs better. Try it and see. You can get the block off plates from Summit, or after yours is unstuck just unhook the vacuum line running to it and plug the line.
     
  7. Burbinator

    Burbinator 1/2 ton status

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    87-91 are fuel injected, Dunc03...the computer will not tolerate the elimination of the EGR from the equation without some major retooling other than just disconnecting it.

    I vote for the O2 sensor, sticky EGR or a bad injector on the TBI...

    The learning curve is a toll road...ride with someone who has already paid!
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  8. rocko

    rocko 1/2 ton status

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    I replaced the O2 with a new one about 1 month ago..
    And where can i buy a new EGR ? any part's store? As for clogged injector... wouldn't it be weak through the whole powerband? it only act's up around 35 mph and 65 mph..

    I haven't failed, I've found 10,000 ways that don't work. www.rocko.rockcrawler.com
     
  9. Burbinator

    Burbinator 1/2 ton status

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    I'd check the operation of the EGR before shelling out for a new one.

    Does your "service engine soon" light come on when you turn the key to run?

    The learning curve is a toll road...ride with someone who has already paid!
    <a target="_blank" href=http://photos.yahoo.com/abshort1>U.S.S. Nimitz II</a>
     
  10. rocko

    rocko 1/2 ton status

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    The service engine light has been coming on about after 20 to 30 minutes of driving... and yes.. when I turn the key, the light comes on only for a few second's..
    How do I check the operation of the EGR? What does it look like on a 89 Blazer?

    I haven't failed, I've found 10,000 ways that don't work. www.rocko.rockcrawler.com
     
  11. rocko

    rocko 1/2 ton status

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    Burbinator.. on another note... sweet Burb ya got there...
    Another one of my dream trucks..

    I haven't failed, I've found 10,000 ways that don't work. www.rocko.rockcrawler.com
     
  12. Burbinator

    Burbinator 1/2 ton status

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    Thanks, I got it about a month or so ago, before I sold my '82 K10 Sub. I love it!

    On the passenger side of the engine, there should be a black box with heat fins between the TBI and the valve cover. Directly behind that is the EGR valve with a vacuum line going from it to the black box. On the EGR, there should be an open space which you can put a finger (engine front side of valve). Rev the engine manually with one hand and feel for the valve moving with the other. It shouldn't move at idle at all. If it doesn't move off idle, it's stuck either open or closed, or that black box isn't doing it's job. You might want to invest in a code scanner or borrow a friends and suck the computer brain and see what codes it has stored. That will be the best way to know for sure.

    The learning curve is a toll road...ride with someone who has already paid!
    <a target="_blank" href=http://photos.yahoo.com/abshort1>U.S.S. Nimitz II</a>
     
  13. sosamantx

    sosamantx 1/2 ton status

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    hmmmm, maybe a vacuum leak, loose sparkplug wire, or loose/fouled plug??

    <font color=blue>Steve Sosa a.k.a. "sosaman"</font color=blue>
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