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Troubleshooting Engine Performance Problems

By

Part 2

  • Engine doesn't have its normal amount of power:
    When you step on the gas, the engine doesn't seem to have the power or pick up it did before. It feels like the get up and go got up and went. It seems to run okay and there are no unusual noises or vibrations, but the engine just isn't performing well. The problem seems to be getting worse and worse as time goes by time, although you did not notice when it first started.

    Possible causes:

    1. You may have a dirty air filter: Replace the air filter.

    2. The spark plugs may be dirty or worn: Clean and regap spark plugs. Replace spark plugs.

    3. There may be some type of ignition problem: Check and replace distributor cap, rotor, ignition wires and spark plugs.

    4. The ignition wires may be bad: Replace ignition wires.

    5. The fuel filter may be clogged: Replace fuel filter.

    6. The engine may have mechanical problems: Check compression to determine engine condition.

    7. Your catalytic converter may be clogged: Replace catalytic converter.

    8. The exhaust system may be clogged: Replace exhaust system.

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  • The engine will not idle smoothly, or it stalls during idle when the engine is cold:
    When the engine is cold and you take your foot off the gas pedal, the engine runs very rough and may even stall. When you run the engine at higher speeds, it seems to run fine.

    Possible causes:

    1. If you have a carburetor, you may have a bad accelerator pump or power circuit: Replace accelerator pump or replace carburetor.

    2. There may be a vacuum leak: Check and replace vacuum lines as required.

    3. There may be some type of ignition problem: Check and replace distributor cap, rotor, ignition wires and spark plugs.

    4. The ignition timing may be set wrong: Adjust ignition timing.

    5. There may be a fault in the computerized engine control system: Check engine control systems with a scan tool. Test circuits and repair or replace components as required. (Generally not a DIY job)

    6. The EGR valve may be bad: Replace EGR valve.

    7. The engine may have mechanical problems: Check compression to determine engine condition.

    8. Idle speed set incorrectly: Set idle speed to specs.

    9. The fuel injectors may be dirty: Clean or replace fuel injectors.

    ~~~~~~~~~~~~~~~~~~~~~~~~~

  • The engine will not idle smoothly, or it stalls during idle when the engine is warm:
    When the engine is warm or hot and you take your foot off the gas pedal, the engine runs very rough and may even stall. When you run the engine at higher speeds, it seems to run fine.

    Possible causes:

    1. If you have a carburetor, you may have a bad accelerator pump or power circuit: Replace accelerator pump or replace carburetor.

    2. There may be a vacuum leak: Check and replace vacuum lines as required.

    3. The fuel pressure regulator may be operating at too low a pressure: Check fuel pressure with a fuel pressure gauge. Replace fuel pressure regulator. (Generally not a DIY job)

    4. Idle speed set incorrectly: Set idle speed to specs.

    5. There may be some type of ignition problem: Check and replace distributor cap, rotor, ignition wires and spark plugs.

    6. There may be a fault in the computerized engine control system: Check engine control systems with a scan tool. Test circuits and repair or replace components as required. (Generally not a DIY job)

    7. The EGR valve may be bad: Replace EGR valve.

    8. The engine may have mechanical problems: Check compression to determine engine condition.

    9. The fuel injectors may be dirty: Clean or replace fuel injectors.

    ~~~~~~~~~~~~~~~~~~~~~~~~~

  • The engine idles too fast:
    After the engine and it has run long enough to be warm, the idle speed does not come down to normal. You really notice it when you come to a stop and must have to push hard on the brake pedal to keep the car from moving

    Possible causes:

    1. If you have a carburetor, you may have a bad accelerator pump or power circuit: Replace accelerator pump or replace carburetor.

    2. The engine may be overheating: Check and repair cooling system

    3. The fuel pressure regulator may be operating at too low a pressure: Check fuel pressure with a fuel pressure gauge. Replace fuel pressure regulator. (Generally not a DIY job)

    4. The ignition timing may be set wrong: Adjust ignition timing.

    5. There may be some type of ignition problem: Check and replace distributor cap, rotor, ignition wires and spark plugs.

    6. There may be a fault in the computerized engine control system: Check engine control systems with a scan tool. Test circuits and repair or replace components as required. (Generally not a DIY job)

    7. There may be a vacuum leak: Check and replace vacuum lines as required.

    8. . You have a bad idle speed control unit: Replace idle speed control unit

    9. The alternator may not be working properly: Replace alternator.

Additional Information provided courtesy of ALLDATA DIY

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