Rough starts on 99 SL2

Discussion in 'Saturn S-series' started by Doug Miller, Mar 4, 2011.

  1. Doug Miller

    Doug Miller Guest

    99 SL2, AT, just under 130,000 miles. Recently has become difficult to start.
    Engine cranks fine, sometimes fires immediately and runs perfectly, but about
    80% of the time it will fire immediately and either die within seconds, or run
    very rough for ten to fifteen seconds. When it dies, it's difficult to
    restart. Seems to behave better when the temperature is below freezing.

    Spark plugs are new, less than 1000 miles. (Problem occurred before the spark
    plugs were changed.)

    Any suggestions would be greatly appreciated.
    Doug Miller, Mar 4, 2011
  2. Doug Miller

    SteveT Guest

    Hi, Doug,
    Sorry to hear of your problem.
    Google is your friend! :) See
    Good luck.
    SteveT, Mar 4, 2011
  3. I would suspect one of two things, either 1) the crankshaft position
    sensor or 2) the ignition module and attached coils. The crankshaft
    position sensor is a little plastic sensor with a wire coming out of it
    that inserts into the block to detect the rotational position of the
    crankshaft so that the computer knows when to set off the ignition
    spark. The ignition module and coils are what actually create the
    spark. The position sensor costs about $40 and is easy to replace as
    long as you don't mind crawling under the engine. The ignition module
    and two coils (always replace them all) costs about $350 and is also
    easy to replace but you probably want to try the sensor first.
    David T. Johnson, Mar 4, 2011
  4. Doug Miller

    Doug Miller Guest

    Lots of good ideas there. Thanks much. I guess the first thing I'll have a
    look at is the CTS. And I'm pretty sure I'm overdue for changing the fuel
    filter, too.
    Doug Miller, Mar 5, 2011
  5. Doug Miller

    Doug Miller Guest

    Many thanks, Steve. The forum posts pointed me in the right direction: the
    problem was the coolant temperature sensor. The existing CTS was probably
    original equipment; at any rate, it had a plastic tip, which was cracked along
    80% of its length. The replacement (ten bucks at PepBoys) has a brass tip.

    I had one episode of rough starting, the day after changing the sensor. Other
    than that, starts have been perfect for the last week and a half, and fuel
    mileage is back up where it had been before the problems began.

    Thanks again. Let me know if you're ever in Indianapolis; I have a cold
    homebrew with your name on it...
    Doug Miller, Mar 25, 2011
  6. Doug Miller

    SteveT Guest

    Hi, Doug,
    Very glad to have helped! A brew for pointing you to Google is hardly
    merited but I appreciate the offer :) (and, as it happens, I do get to the
    Indi area from time to time as I live near Detroit and my mom lives in Terre
    SteveT, Mar 25, 2011
  7. Doug Miller

    Doug Miller Guest

    Well, I *had* Googled, and came up empty. You pointed me at the Saturn
    forums, and that's where I found the answer. The offer of a brew still stands.
    Ping me here on the group next time you're planning to come through Indy.
    Doug Miller, Mar 26, 2011
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