1997 k2500 Burb 5.7l - Very rough when cold

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by Applegeek, Oct 30, 2008.

  1. Applegeek

    Applegeek New Member

    Got a '97 K2500 'Burb that's started running very rough / missing when cold. It does smooth out and runperfectly fine after about 15 minutes. This is something fairly recent over the last couple months, and I'm kind of scratching my head on this one.

    1. No trouble light.

    2. Scan codes were showing slow heat on rear O2 sensors, but i replaced all 4.

    3. Scan code was also showing a possible faulty throttle position sensor, and that was replaced also.

    4. New spark plugs, wires, cap and rotor installed.

    5. Injector, throttle body cleaned.

    6. New fuel filter installed.

    Fuel pressure seems OK, spark is hot and bright.

    Any clues where to look next? Its getting to the point where its almost stalling first thing in the AM...almost like my old '67 ford truck with a manual choke, but that's another story...<Laughing!>
  2. MrShorty

    MrShorty Epic Member 5+ Years 1000 Posts

    Scan codes point to problems in circuits, of which the sensor is only part. If replacing the O2 sensor(s) didn't resolve the O2 sensor heater circuit code, I would start looking at the rest of the O2 sensor wiring/grounds.

    Did replacing the TPS resolve the TPS code?

    What does "fuel pressure seems OK" mean? 50+ psi all the time?
  3. Applegeek

    Applegeek New Member

    Yes, the trouble code with O2's and TPS went away, so those seem fine.

    Yes, fuel pressure is right about 53~56 psi all the time.

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