350 idle problems

Discussion in 'Engine & Performance' started by jgarner87blazer, May 4, 2011.

  1. jgarner87blazer

    jgarner87blazer Junior Member

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    I have a 87 blazer with a 350 tbi motor. Im having surge problems at idle. I have replaced - O2,TPS, MAP, IAC, temp sensor and dont have any vac leaks.
    Its runs pretty good after it warms up but the idle is high at that time. Its driving me crazy and Ive spend a lot of money trying to fix it. I need help. I have read everything on the internet and its the same stuff.
     
  2. Swims350

    Swims350 Full Access Member

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    check the egr?
     
  3. 89Suburban

    89Suburban Full Access Member

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    There are two temp sensors, you replaced the one on the intake manifold, right?
     
  4. jgarner87blazer

    jgarner87blazer Junior Member

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    yes i replaced the right sensor. the one in the intske. my mechsnic says the egr has nothing to do with the idle issue.
     
  5. 89Suburban

    89Suburban Full Access Member

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    I guess if the EGR was sticking opn it would hardly idle, that would be right. Maybe the butterfly isn;t hittin the idle stop, did you try disconnecting the throttle cable and moving the throttle by hand an making sure it is hitting the idle stop?
     
  6. HotRodPC

    HotRodPC Administrator Staff Member

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    If you're mechanic tells you, EGR has nothing to do with idle issues, you need a new mechanic.

    If an EGR valve gets corroded and dirty with carbon from the exhaust, and it can't close off all the way, then you have an internal vacuum leak. It has everything to do with idle quality.
     
  7. Swims350

    Swims350 Full Access Member

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    x a freakin million.

    not to mention if you have a mechanic why would you be neededing to ask about it here? Or anywhere, if he's a mechanic he should be able to figure it out, period. if you're doing it yourself or question him, then by all means ask away.

    I had a bad idle in my 88 and it was over the egr being bad. I blocked it off and just deal with the light coming on every now and then.

    I hear even new ones have issues, I was told to only replace them with a gm, ac delco or delphi brand, NO OTHER!!!!!!!! They'll act up if you do.

    A simple vacuum test will tell if it's leaking or not. Plus not asure on your 87 but my 88 has a vac. solenoid for egr.
     
    Last edited: May 4, 2011
  8. HotRodPC

    HotRodPC Administrator Staff Member

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    There is 2 reasons to fire the mechanic. #1 he obvioulsy doesn't know what he's talking about, #2, you have GMSB now. FIRE THE MECHANIC !!!
     
  9. 89Suburban

    89Suburban Full Access Member

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    :popcorn:
     
  10. Swims350

    Swims350 Full Access Member

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    I would agree, I'm sure the guys on here could help you figure out what it is, or tell you what it is. Only thing we can't do is fix it for ya, but if somebody was close enough I bet they might lol.
     
  11. bucket

    bucket Super Moderator Staff Member

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    Agreed, EGR will cause idle issues. Check for slop in the throttle shaft of the TBI unit. If worn, it can cause intermittent vacuum leaks as well as a binding issue that keeps the throttle from fully closing.
     
  12. jgarner87blazer

    jgarner87blazer Junior Member

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    Ive tired everything but the egr. How can i block it off. Should I by-pass egr. How is that done?
     
  13. 89Suburban

    89Suburban Full Access Member

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    Some guys here have done it, made a plate out of tin or something to stick under it.
     
  14. Swims350

    Swims350 Full Access Member

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    they sell them online and at the local auto parts stores, just ask for an egr block off plate, or I can find the part numbers for you. I think one is made by holley, or wieand and is 9007. You'll need a gasket too they don't come with the plate anymore. ebay has them and so does summit. if you have a hand vacuum pump you can test it and if it doesn't hold vac. it's junk.

    One quick way is to just unhook it's vac. line and plug that line with a screw or bolt, or remove it from the carb and put a vac. cap on it. That may help some, but if the egr is carbon'd open and not shutting, it needs removed to fully know if it's the problem.
     
  15. 89Suburban

    89Suburban Full Access Member

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    Ok, so a local store should have it, cool. :High 5:
     

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