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GM Code scanner; detected some problems...what?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Boss, Oct 20, 2001.

  1. Boss

    Boss 1/2 ton status Author

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    Ok, for those who know that my brother's 88' S10 Blazer, 2.8L TBI is having major problems. It like stalls and shudders at low speeds and sounds like it's knocking when accellerating pass 15mph.
    I bought a GM code scanner and tried it out. Here are the codes that came up:

    Code 13: Oxygen (O2) Sensor-signal stays low ("lean") durning warm engine cruise or sensor circuit is open or left sensor circuit is open (dual sensor models)

    Code 33: Mass Air Flow (MAF) sensor-signal voltage or frequency is high duriing engine idle.
    OR
    Manifold absolute pressure (MAP) sensor-signal voltage is high during engine idle
    (Note: Engine mis-fire or unstable idle may cause this code.)

    Code 44: Lean exhaust indication-oxygen (O2) sensor voltage stays low after one or two minutes of engine run. (Left sensor on dual sensor engines)

    Those are the problems the computer picked up.
    Any yall know what they mean and what needs to be done to fix em? Thanks again....I'm computer engine illiterate [​IMG]
    Boss

    Pic of my truck Before N' After
    <a target="_blank" href=http://coloradok5.com/gallery/BeforeNAfter>http://coloradok5.com/gallery/BeforeNAfter</a>
     
  2. MudFrog

    MudFrog 1/2 ton status

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    Boss... Did you check the codes in your haynes manual? They give explanations and what you can try to fix them.

    89 K5 Silverado
    <a target="_blank" href=http://mudfrog.rockcrawler.com>http://mudfrog.rockcrawler.com</a>
     
  3. I was looking at your post and it sounds like you definitely have a bad O2 sensor, and your (MAF) or the wiring to the MAF is bad. I'd definitely do a OHMS check on the MAF to see if its bad or the wiring. Then I would clear the codes in the computer and run it to see if that fixed the problems. That way you can eliminate 2 of the problems and see if they caused the MAP code to come up.

    Later,
    Doug



    4 wheelin's not a job, it's an adventure!
     
  4. Dznutz70

    Dznutz70 Registered Member

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    When was the last time the fuel filter was changed? On my cousins 94 blazer with tbi, code 44 was caused by a clogged fuel filter.
     
  5. Boss

    Boss 1/2 ton status Author

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    The Fuel Filter was supposedly changed about 10K miles ago when he had it professionally done (they did the complete tune up). I will change the O2 sensor and then possibly the fuel filter too. I'll check out the MAF wires....thanks
    Boss

    Pic of my truck Before N' After
    <a target="_blank" href=http://coloradok5.com/gallery/BeforeNAfter>http://coloradok5.com/gallery/BeforeNAfter</a>
     
  6. HarryH3

    HarryH3 1 ton status Author

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    Also check for a massive vacuum leak somewhere. This will cause the MAP sensor to read high at idle and will also create a lean condition.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
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  7. Stoopalini

    Stoopalini 1/2 ton status

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    If the O2 sensor was the problem, it would run fine for the first few minutes after starting it. The computer uses "open loop" when 1st started up and ignores readings from the O2 sensor while in this mode.

    After the temp comes up, and other conditions are met, the computer goes into "close loop" mode and starts taking the O2 sensor's readings into account.

    I'm not saying the O2 sensor is not bad, but if it was bad, it wouldn't cause all the problems he is having.
    I would trace the wires to the O2 sensor before replacing it, and make sure they haven't made contact with the exhaust and caused a short.

    I believe the MAF sensor can be cleaneed and the MAP sensor can be calibrated. I would look into these as the cause of the problem.

    Like Harry said, if there is a vacuum leak, it could be the cause. Check the air intake for any holes, or for anything lodged in the way.

    Good luck,

    Thomas.

    -- '84 1-Ton Blazer --
    When the goin' gets tough,
    the tough go 1-Ton [​IMG]
     
  8. CaptCrunch

    CaptCrunch 1/2 ton status

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    I agree w/ Harry... check for a vacuum leak and/or test the MAF or MAP sensor. The complaint sounds very typical of a bad MAF or MAP

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
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  9. BurbinOR

    BurbinOR 3/4 ton status

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    Speaking of scanners, what do you guys have?

    My engine builder has a Snap On model...........however, having bought thousands of $ worth of Snap On tools over the years bet they ain't cheap. Any other recommendations? Want one that reads all the data and not just a code reader.



    <font color=blue>'79 ONE TON TPI K5 - See it at---&gt;<a target="_blank" href=http://www.blazzinor.rockcrawler.com>www.blazzinor.rockcrawler.com</a>
     
  10. HarryH3

    HarryH3 1 ton status Author

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    Frank, I've got the Auto X-Ray scanner. It works pretty nice for the money. Picked it up at the local Checker Auto Parts for $150. It does real-time data monitoring and has a capture mode for intermittent problems. You can only look at the data from one sensor at a time in real-time mode. You can step through the sensors and look at them, but only one by one. It would be nice to be able to see several at once on a laptop screen. But the software I've seen to do that kind of stuff was $500 and up. [​IMG]

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
    It's a great day to be alive...
     

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