1998 S1 runs sluggish and rough after full warmup, but only intermittantly

Discussion in 'General Motoring' started by Mgtaylor, Nov 25, 2005.

  1. Mgtaylor

    Mgtaylor Guest

    This Saturn S1 (1998) runs good most of the time but will after running for
    a good long time will sometimes begin chugg1ng and running rough. There is
    a trouble code in the computer for coolant sensor, but of course the car
    does not misbehave like this whenever the mechanic has been looking at it!
    Due to previous idling problems, which were fixed, the CPS. MAP, Throttle
    speed and Idle speeds sensors have been changed over a period of time this
    summer. This rough running seems to be a new problem. Sometime it will
    run rough for a few minutes and then clear up, sometimes it continues
    until the car is shut down and cooled off for a while. The fuel pump
    pressure is at 45-50 lbs - could this be the problem? Thanks in advance
    for any replies to this.
    Mgtaylor, Nov 25, 2005
  2. Mgtaylor

    Bob Shuman Guest

    What are you waiting for? Replace the Coolant Temperature Sensor. Sounds
    like it is intermittently reporting a cold engine so you are getting too
    much fuel and it runs rough. These are known to fail often and are cheap
    and easy to fix.

    Bob Shuman, Nov 25, 2005
  3. Mgtaylor

    Mgtaylor Guest

    Thank you for your answer Bob. The coolant sensor code is gone and now I
    have a P0301 - missing on cylinder #1. This code only shows up when it is
    actually malfunctioning (random) which is why the mechanic has not seen it.
    According to the manual there can be a whole plethora of causes for this
    including spark plug, plug wire, low fuel output at injector(s), coil,
    emissions components, ignition weak or vacuum leak.

    There are no other trouble codes so far. Could low fuel output cause this
    only in cylinder #1 because #1 is at the farthest point of the injector
    assembly from the fuel input?
    Mgtaylor, Nov 26, 2005
  4. Mgtaylor

    Bob Shuman Guest

    I'd guess you have a dirty connector on the fuel injector or a bad wire or
    plug. You can use some electronic contact cleaner to clean the connector
    and then see if it comes back. I'd also take a look at the ignition coil
    tower and all spark plug connections there too. They get corroded and can
    short out. You can easily remove and clean this off to remove the
    corrosion/growth. Could also be a head gasket leak, but I would not jump
    to that conclusion just yet.

    Good luck.

    Bob Shuman, Nov 26, 2005
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