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350 tbi

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 4x4k20, Mar 31, 2001.

  1. 4x4k20

    4x4k20 1/2 ton status

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    i have an 88 jimmy when you mash the gas pedal slightly it acts as if it wants to go dead any ideals what causes this? it does fine when you mash the pedal about halfway

    4x4k20
     
  2. Emmettology 101

    Emmettology 101 3/4 ton status

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    Your injectors may be clogged... Does the tranny jump down into a passing gear?

    Mike [​IMG]
    See <font color=green>EMMETT</font color=green> -&gt; <A target="_blank" HREF=http://emmett.coloradok5.com>http://emmett.coloradok5.com</A>

    "He who uses a winch...... Is tired of yankin!"
     
  3. 4x4k20

    4x4k20 1/2 ton status

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    the injectors were replaced and yes the trans does go in and out of od its main problem is at part throttle if you give it alot of gas it will go on could it be my tps ?

    4x4k20
     
  4. Emmettology 101

    Emmettology 101 3/4 ton status

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    not just oD though, I mean if you are crusiing along at say 40 and in 3rd, then mash the throttle and it should shift down..

    Your TPS may be out of adjustment, but on K5's I am not sure how to adjust them.

    Mike [​IMG]
    See <font color=green>EMMETT</font color=green> -&gt; <A target="_blank" HREF=http://emmett.coloradok5.com>http://emmett.coloradok5.com</A>

    "He who uses a winch...... Is tired of yankin!"
     
  5. HarryH3

    HarryH3 1 ton status Author

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    There are 2 major inputs to the ECM when you move the throttle. One is the throttle position sensor (TPS) and the other is the manifold absolute pressure (MAP) sensor. Without a scan tool that lets you see what they're doing in real time, they're somewhat difficult to troubleshoot. [​IMG]

    But basically they're both just potentiometers, so you can do some basic troubleshooting with an ohm meter. It's easier to use an analog meter than a digital one, since you want to look for the needle jumping as the sensor moves through its range of motion. It's not easy to see odd patterns with a digital meter, since the numbers are always changing anyway. You also need a variable vacuum source to test the MAP sensor.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <A target="_blank" HREF=http://ThunderTruck.ColoradoK5.com>http://ThunderTruck.ColoradoK5.com</A>
     
  6. pcorssmit

    pcorssmit 1/2 ton status

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    Another fairly crude method is to try disconnecting the suspect component, and see if it runs any better. The computer basically substitudes a fixed value for the actual reading.

    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  7. jarheadk5

    jarheadk5 1/2 ton status

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    I'm not exactly sure what you're describing; when I hear "mash the pedal" I think of flooring it. But if what you mean is a part-throttle stumble, I just replaced the TBI gasket and that cured my stumble.

    [​IMG] Semper Maintenance!
     
  8. 4x4k20

    4x4k20 1/2 ton status

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    replaced tps truck does fine now

    4x4k20
     

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