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-   -   1985 Nissan 300ZX Turbo Running Rough (https://www.askmehelpdesk.com/showthread.php?t=241659)

  • Jul 25, 2008, 03:14 PM
    DanPatrick10
    1985 Nissan 300ZX Turbo Running Rough
    OK, I've had this car for 5 years and it always ran great. Did regular oil change and tune-ups. The car began running rough a few months ago and has also been difficult to start, so I got it a tune-up and a new battery but the problems still exist.

    First, it's hard to start when cold. I've got to give it 3-4 cranks before it'll turnover. After it starts it will run and idles as normal (700-800 rpm) but runs rough. Also, after starting it and putting it in reverse, it feels like it wants to stall. Could my fuel pump be worn out and if it is worn is there anything I can do to test it?
  • Jul 25, 2008, 03:32 PM
    TxGreaseMonkey
    The problem is most likely electrical-related, not fuel. Here's what I would do:

    . Replace Ignition Control Module (ICM):

    While we find your parts, please enter your ZIP Code at PartsAmerica.com

    . Replace coil.

    Main culprit is likely the ICM.

    . Replace fuel filter.

    Hopefully, the tune-up included replacing spark plugs (NGK), spark plug wires, rotor, and distributor cap.

    If the problem persists, consider replacing the Engine Coolant Temperature Sensor, which affects fuel injector pulse width. It's located on the thermostat. The ECT Sensor is a temperature dependent resistor (thermistor), whose resistance decreases as the engine coolant temperature increases. It provides a richer mixture when cold, leaner mixture when hot.
  • Jul 26, 2008, 01:38 PM
    DanPatrick10
    Is the ICM simply the ignition module? I did notice the car seems to run better when its warm.
  • Jul 26, 2008, 01:55 PM
    TxGreaseMonkey
    Yes.

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