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Lean mixture on TBI 350

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 90BlazerK5, Apr 7, 2002.

  1. 90BlazerK5

    90BlazerK5 Registered Member

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    I've been noticing a black smoke from my tailpipe under havy load situations. WEll, when I put my code reader on it, it came back with a code 44, which is a Lean reading/ Now, how can I fix this on a TBI unit? This is the stock engine in a '90 k5, with 166,000 miles on it. Thanks in advance for any ideas!
     
  2. fortcollinsram

    fortcollinsram 1/2 ton status

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    I'd check/replace your O2 sensor and see what happens...Also check your AIR system...

    Chris
     
  3. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Something isn't adding up correctly here. Black smoke means it is rich not lean. I would however either test your 02 sensor or replace it to start with. I would also look at your map sensor and TPS switch.
     
  4. Nrose07

    Nrose07 1/2 ton status

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    So what did you figure out???
     
  5. René

    René 1/2 ton status

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    Michelbach, Germany
    Check the ECM wiring connection terminals.
    Have the fuel pressure checked.
    Check the oxy sensor wire.
    Check the trottle body gasket, vacuum hoses and intake manifold gaskets for leaks.
    Replace the oxy sensor.

    In this order…
     
  6. On fuel injected vehicles, if the O2 sensor is bad, it will cause a lean mixture code. When the O2 goes out, the ECM sees it as a lean mixture condition and compensates by delivering more fuel causing the black smoke in the exhaust, which is normally the rich mixture condition symptom on carburated vehicles.
     

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