1994 chevy silverado with a 5.7L TBi/ Idling problem.

Discussion in 'Chevy Truck Forum' started by mando1, Jun 13, 2018.

  1. mando1

    mando1 Full Member

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    Good Morning to all. Darn it,I'm still having idling problems with this truck. When its idling,if I don't keep my foot on the gas pedal,it will die.Also,when I come to a traffic light or a complete stop,it dies.It starts right up all the time.Going down the road it runs great,nice and smooth.Has plenty of power.This is what I have replaced so far and still have the problem.
    Coolant Temp.sensor,IAC,Map Sensor and EGR. I replaced the fuel pump about 2 yrs ago and also the fuel filter.
    The only 2 things I have not replaced are the TPS and the oxygen sensor. I ran a test on the tps sensor and it checks ok. Don't know what to check anymore,ran out of ideas. When the AC is on and the truck is idling,I put it in neutral and rev up the engine a bit to keep it from shutting off. Maybe you guys might have another idea that can pass on to me regarding this problem.Any help will be appreciated very much.
    Mando
     
  2. Kennyray

    Kennyray Moderator
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    Have you checked your timing?
     
  3. leolkfrm

    leolkfrm Full Member

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    did you forget to reconnect the wire?...vac leak?
     
  4. mando1

    mando1 Full Member

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    Timing is good. All the wires are connected to their respective sensors,no loose connections eighter.
    It does sound like a vacuum leak but I checked all the vac. hoses and even sprayed around the intake to make sure there were no leakes there. Will keep checking.Thanks for your suggestions.
    Mando
     
  5. greencamaro1981

    greencamaro1981 Full Member

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    fuel filter, change it its easy and like 7 bucks. are you getting a clean fuel spray from the tbi?
     
  6. mowfixer

    mowfixer Full Member

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    I would get a cheap vacuum gauge and connect it. Best way to diagnose a problem like that is to see what vacuum reads at an idle.
    Use mine all the time.
     
  7. leolkfrm

    leolkfrm Full Member

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    might double check the seal on the egr, make sure it is not sticking, vac line to power brakes
     
  8. mando1

    mando1 Full Member

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    Thanks to all for your help and ideas. The fuel pump quit about 2 years ago and I went ahead and replaced it along with a new fuel filter. The EGR is brand new and has a new gasket. The big vacuum line that goes to the brake booster is good. I do have a mightyvac tester.I connected it to the one of the ports coming off the tbi and when the idle comes up,it reads 20 and as the idle goes down,it drops to about 10. Like I said,it will not stay idling steady at all. It surges all the time. Where are the best places to hook up the mightyvac to check the vacuum? Also,do think that maybe replacing the fuel injectors would take care of the problem?
    I bought this truck brand new in 1994 and I have never done anything to the tbi. Was thinking it might be time for eighter injector replacement or complete tbi rebuilding.
    Mando
     
  9. gmctrucks

    gmctrucks Full Member

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  10. gmctrucks

    gmctrucks Full Member

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