Losing power on Outback

Discussion in 'Subaru Outback' started by Dave N, Jun 23, 2005.

  1. Dave N

    Dave N Guest

    A problem has developed with our 1996 Legacy Outback, and I'm hoping you
    folks can help me narrow down the problem before I take it in for
    service again. The symptoms are that in the morning, when the car is
    still relatively cold, it will lose power during acceleration (like when
    getting on the freeway). Sometimes it will be so bad as to stall out,
    and I'll need to pull over and wait for a couple minutes before starting
    the engine again. After that, it seems to be ok. Oftentimes, the
    "check engine" light will come on for a few minutes or hours, then go
    off again.

    This problem started last fall. It happened a few times before the
    check engine light came on. The first time that happened, I took it to
    a local repair shop. They put it on the computer and read the code --
    misfire on #3 and 4 cylinders. The mechanic did a maintenance tune-up
    (which included replacing the plug wire set, plugs, fuel filter, oil and
    filter, fluids, top radiator hose, antifreeze, carb cleaner).

    The problem might have gone away for a couple weeks, but it came back.
    It was time for the 90K mile service anyway, so I took it back to the
    mechanic a few months later. He read the codes from the check engine
    light again, and found the same thing -- misfire on #3 and 4 cylinders.
    He did the 90K servicing, but didn't find anything new about the

    The problem continued for awhile, then went away for a couple months.
    It's been a bit warmer lately, so that may have had something to do with
    it. This week was a little colder and rainy, and the problem hit again
    yesterday. It lost power and stalled out, but this time it was while I
    was decelerating, coming up to a stop light. Otherwise the same
    symptoms, and the check engine light is on again.

    I need to get this fixed! I don't know much about car engines, but I've
    got the Chilton's manual and I'm fairly handy. I'm hoping someone can
    either suggest some things I can try on my own to isolate or repair the
    problem, or else give me some ideas to bring to the repair shop so that
    I'm not hit with a high troubleshooting bill. Any help is appreciated.
    Dave N, Jun 23, 2005
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  2. Dave N

    Dave N Guest

    I found an old message
    u*&rnum=3&hl=en#4172b9107100e7a9) that indicates it might be the
    alternator going bad. Does that make sense? Is there a way to test the
    Dave N, Jun 23, 2005
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  3. Dave N

    Jim Stewart Guest

    The only thing I can suggest is looking under
    the hood at night in the dark while the engine
    is running. Look for arcing around the coil
    pack. The car should also be cold when you do

    I'm guessing that cold and condensation is causing
    the coil pack to short out until it gets warm.

    Just a guess though...
    Jim Stewart, Jun 23, 2005
  4. Dave N

    Dave N Guest

    Thanks, Jim. I'm thinking it's a good guess. I've done a bunch of
    Google searches in the last couple hours, and apparently this is a
    common problem. It's always tripping the misfire codes for both #3 and
    4 cylinders, and one of the things they have in common is the coil pack
    (according to a few posts I've found).

    So I'd like to try your suggestions. Erm... what is the coil pack, and
    how can I find it?
    Dave N, Jun 23, 2005
  5. Dave N

    Dave N Guest

    Hold on, is the coil pack the same thing as the ignition coil? I found
    that in my manual. Looks like I need to check primary and secondary
    resistance, and maybe replace it. This could be a cheap and easy fix!
    Let me know if I'm on the wrong track...
    Dave N, Jun 23, 2005
  6. Dave N

    Edward Hayes Guest

    Coil pack idea and the dark test for ignition shorting sounds good to
    me. In addition since it does it during damp/rainy conditions I would
    remove and clean the battery terminals AND ground connections as a
    oxidation film may have built up and absorb moisture.
    Edward Hayes, Jun 23, 2005
  7. Dave N

    Jim Stewart Guest

    Here's a picture of my car. The coil
    pack has the 4 red wires coming out of
    it. It's called a coil pack because
    there are 2 coils and each coil is double-
    ended, with each end going to a plug.


    As the the resistance check, you can do
    it, but it may test good and still be
    bad. Given that your problem goes away
    when the car is warm, I suspect that it
    only fails when it is cold and under

    Still just all speculation, but that's
    about all you can do at this point.
    Jim Stewart, Jun 23, 2005
  8. Dave N

    Dave N Guest

    Thanks, Jim, I really appreciate your help. Both of these trips to the
    repair shop cost me $400, and it looks like the coil pack is about $85.
    That seems like a good suspect, so I'll check and probably replace it.
    If it might save me the cost of another repair shop bill, it's worth a
    try. (Of course, now that summer's here, I may not know if that fixed
    the problem until fall.)
    Dave N, Jun 23, 2005
  9. Dave N

    Dave N Guest

    Thanks, Edward. I'll follow your suggestions in addition to the coil pack
    Dave N, Jun 23, 2005
  10. Dave N

    Edward Hayes Guest

    Interesting stuff on the coil pack resistance. Why not cool down the
    coil pack with ice bags for an hour or so and test with ohm meter to
    see if things change vs. warm and or drive when you cool down the coil
    pack. This way you could isolate the failure mode and part. Ed
    Edward Hayes, Jun 24, 2005
  11. Dave N

    Jim Stewart Guest

    Or spray it with circuit cooler. The cold and
    condensation might let you reproduce the failure.
    Jim Stewart, Jun 24, 2005
  12. Dave N

    Alan Ronemus Guest


    Your problem is rather generic, and I wouldn't put too much faith in the
    misfire codes. What you really need is a diagnostic check while it's failing.
    The diagnostic codes may not reflect the actual problem since the ECU is rather
    simple-minded and only checks for a limited number of faults. The check for
    high-voltage discharges is quick and easy, but the problem could also be in the
    ECU or the wiring harness; reseating the connectors on the ECU, coil pack, and
    any intervening connectors may fix the problem. If it fails again, limp to a
    dealer if possible and have them check it before it starts to work again.

    I had a similar problem with a Toyota that turned out to be the throttle
    position sensor. The problem was intermittent (stranding me 3 times) and there
    was nothing to be found after it sat for a while. I took it to a dealer while
    the problem was happening and they immediately found the bad sensor. I had
    similar problems with a VW Rabbit years ago, and it turned out to be worn
    contacts in the ignition switch - fortunately, the switch was much easier to
    replace than it is on modern cars.

    Alan Ronemus, Jun 25, 2005
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