Concorde missing on hills

Discussion in 'Concorde' started by Christopher Moss, Oct 26, 2005.

  1. Gents,
    I have a problem with my 2003 Concorde Ltd. It has very low mileage
    (only 16000km - I work all the time and never go anywhere!) and has been
    serviced regularly. Problem is when I do try to go somewhere - as soon
    as I go up a hill the engine starts to miss on a cylinder and runs
    rough. The engine light will blink and then at the top of the hill
    settles down and glows steadily. Next hill it will blink for a while and
    the engine will miss again, then it glows steadily once more. It has
    been in to the dealer three times with this, and each time they change a
    gummed-up spark plug and say the computer says there's nothing else
    wrong. I'm putting premium gas in it; they attribute it to bad gas.
    I'm no mechanic, but it seems the mixture is not adjusting for the
    workload of a hill, and this gums the plugs. The light behaviour fits in
    with the emissions being worse as it misses on the hill, and then
    smooths out on level ground again, no? I have heard of a gas cap problem
    affecting the engine warning light - would that behave this way? Any
    other ideas I can suggest to the geniuses at the dealers?

    Christopher Moss, Oct 26, 2005
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  2. Christopher Moss

    damnnickname Guest

    Chris, first of all use the gas that is recommended for that engine, if you
    are not supposed to use high octane dont!! It will cause drivabilty
    You are experiencing a secondary ign problem,find out if the plug is
    fouling due to oil consumption
    on the spark plug or possible a bad coil causing low voltage to the plug.
    You can always get a second opinion from another shop also. you yourself
    can swap the coils out on the cyl, if number 3 is fouling, swap the coils
    with cyl 4 to see if the problem goes to that cyl, if it does, replace the

    Glenn Beasley
    Chrysler Tech
    damnnickname, Oct 26, 2005
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  3. Christopher Moss

    Tommy D Guest

    I had a car with a similar problem. Turned out to be a defective
    catalatic converter. When the car went uphill, the contents shifted
    back, limiting the flow of exhaust. The backpressure sometimes slowed
    the car to a crawl

    I don't know what it takes to loosen up the exhaust somewhere before
    the converter on your car( mine required loosening 3 bolts), but if
    access is easy, the testing would be simple. Open it up enough to
    relieve pressure, then drive noisily up a hill. My situation was
    rather rare, but I too had tried everything else. As a minimum, you
    may want to look under the car for obvious physical damage to the
    exhaust system.

    They might also consider defective wiring to the fuel pump, or
    something clogging the fuel lines, filter or tank.

    To me, your situation seems more mechanical than electronic.

    I slept in a Holliday Inn last night.


    Problem is when I do try to go somewhere - as soon
    Tommy D, Oct 26, 2005
  4. Christopher Moss

    Joe Guest

    Call me a skeptic, but I think missing on hills is always a high-tension
    ignition problem. I'm quite surprised that the OP'd dealer didn't changed
    the plug wires, although I realize you'll probably say "Oh, yeah, they did,
    but I forgot to say so."

    The easy diagnosis is a plug wire. But, if not, it still could be a coil or
    a plug getting fouled. What causes that phenomenon is that when you lug up a
    hill in overdrive, the cylinder pressure is as high as it ever goes. That
    makes dense gas in the cylinder, and more electrical resistance to the
    spark. So, when your car starts to only miss under certain conditions, those
    are always the conditions. That's the worst condition for ignition.
    Joe, Oct 27, 2005
  5. Christopher Moss

    Bill Putney Guest

    He's more likely to say "It doesn't have plug wires - this engine is
    coil-over-plug". :) But you're right about coil or plug possibly
    causing that.

    Bill Putney
    (To reply by e-mail, replace the last letter of the alphabet in my
    address with the letter 'x')
    Bill Putney, Oct 27, 2005
  6. Christopher Moss

    Steve Guest

    He's more likely to say "A 2003 Concorde doesn't HAVE plug wires, it
    uses coil-on-plug ignition." :)

    That said, I agree with you. It may be a dead coil or internally cracked
    insulation on that particular coil, which is effectively the same as a
    bad plug wire.

    Or the engine's sucking oil on that cylinder and repeatedly fouling the
    plug- I'd be especially concerned about that if it's a 2.7L.
    Steve, Oct 27, 2005
  7. OK...this should be a fairly easy problem for a competent diagnostician
    to nail. Key word being "competent". I am guessing (but it is *only* a
    guess) the problem lies with the secondary side of the ignition system,
    which on your car means the spark plugs, the plug "wires" (actually
    boots with internal conductors, connecting the one-per-cylinder coil to
    its spark plug), and the coils themselves.

    A very common cause of persistent misfire is as follows:

    Misfire occurs due to secondary voltage leak down spark plug insulator
    to ground. First component replaced is spark plugs, but plug boots have
    also been affected, so affected plug boots continue to allow voltage
    leakage. Misfire persists, so spark plug boots are replaced, but plugs
    are left alone since they were just replaced. But, faulty plug boots
    caused leakage path on plug insulators. Back and forth and back and
    forth. Often a persistent misfire of this nature will go away when
    plugs AND wires are replaced at the same time.

    Again, though, this assumes the problem originates in the ignition
    system. It's possible there is a fuel system problem-anything from a
    flaky injector to a problem with the engine management system that
    drives the injectors, and several other possible issues as well. That's
    why my guess is only a guess. You need the services of a good
    Horsepucky. There's obviously something wrong. It is lamentably hard to
    find competent and motivated diagnosticians at Chrysler dealers. Very
    easy to find lazy and ignorant ones, though. (Some of them post
    barely-coherent non-answers here!). If they're not taking the vehicle
    for uphill drives with the diagnostic computer ("scanner") hooked up
    and recording the datastream from the vehicle's own computer, then
    they're not doing their job. Perhaps you should shop for a good tech at
    a location other than a stealership, er, dealership.

    As far as "gummed up" spark plugs...this covers a lot of territory. The
    correct term is "fouled" spark plugs, and there are lots of different
    ways spark plugs can foul, and different causes for each different kind
    of fouling.
    How come? It's not "better". Using higher-test fuel than is recommended
    probably isn't causing your symptom, but it's also not doing you any
    good. Just a waste of money. Look in your owner's manual and follow the
    fuel recommendations found therein.

    Possible, but not terribly likely. Bad gas does not selectively affect
    individual cylinders.
    The Check Engine light does not monitor emissions *per se*. It monitors
    engine systems and parameters that *affect* emissions, but it's not an
    excessive-emissions indicator light as such.
    No, not at all.
    See above. If your car is out of warranty, there's NO reason to take it
    to the dealership-and every reason not to.

    Daniel J. Stern, Oct 27, 2005
  8. Christopher Moss

    Bill Putney Guest

    Damn, Steve. Read both of our first sentences. That's scary!!

    Bill Putney
    (To reply by e-mail, replace the last letter of the alphabet in my
    address with the letter 'x')
    Bill Putney, Oct 27, 2005
  9. Christopher Moss

    Steve Guest

    Bill Putney wrote:

    I did, after I sent my reply. Yes, it scared me... but it should
    probably scare YOU more... ;-)
    Steve, Oct 28, 2005
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