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Odd stumbling problem after heating up

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by chev4life, Jan 8, 2003.

  1. chev4life

    chev4life 1/2 ton status

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    This problem has been around for awhile on my '87 K5 TBI..I pretty much replaced everything and to no avail. I have finally put a tach in along with a few other gauges and now I think I have a little more info on my problem. When the truck is warming up the tach is solid and truck runs great...but after it is heated up and I come to a stop...I can watch the tach fluter...she idles at about 600rpm in gear and the tach will sit there for a few seconds and then jump suddenly with no phisical jump noticed and then fall right back down to normal idle. The truck will also stumble a little during this time. Does anyone have an idea of what this could be? Any help will be great.
     
  2. Ck1500

    Ck1500 1/2 ton status

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    my guess would be EGR, mine did the same thing on my 1987 K-5 if ya want a cheap fix to get ya by till you buy a new one, take a needle and puncture the bladder for the egr and it will not stumble when warm then, might notice a little less gas mileage but i did it for 2 weeks when money was tight, just a thought

    Ck1500

    /forums/images/graemlins/ears.gif
     
  3. chev4life

    chev4life 1/2 ton status

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    Already replaced the EGR, O2 sensors, IAC, ETC recently and cap, rotor, coil, plugs, wires, fuel pump, and injectors about 8-10k miles ago. Some I talked to thought it could be the coil gone bad or the ignition module or the distributer pickup or wires gone bad. Any ideas?
     
  4. schmuck

    schmuck 1/2 ton status

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    doubt it is the coil they usually just go out also check to see if the egr is working just see if you can move the diafram also check pcv it could be stuck this will cause a bad idle /forums/images/graemlins/k5.gif
     
  5. 87sm465np208

    87sm465np208 1/2 ton status

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    how hard should the diaphrame be to move? and would it cause a "rough" idle
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    It takes a bit of effort to move (since you can only use the tips of your fingers) but it should be smooth movement. And if it sticks, it can cause a rough idle (and other problems). The engine won't be able to run (likely) if EGR is stuck full open at idle.
     

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