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  1. #1

    Question 1997 k2500 Burb 5.7l - Very rough when cold

    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!>
    '87 C2500 Burb, 5.7L 567k miles, dino oil changed every 10~12k
    '97 K2500 Burb, 5.7L 148k miles, dino oil

  2. #2

    Default

    Quote Originally Posted by Applegeek View Post
    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!>
    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?
    '98 K1500 Suburban LS 5.7 L 4L60E NV246 ARB
    '92 Ford Explorer XLT 4x4 4.0 L A4LD BW13-54 Trac-loc rear
    "My toys were the greasy cogs and springs and pistons that lay around all over the place, and these, I can promise you, were far more fun to play with than most of the plastic rubbish children are given nowadays." Danny in Roald Dahl's Danny The Champion of the World

  3. #3

    Default

    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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