1990 Dodge Spirit 3.0 V-6 Emission Test Failure

Discussion in 'General Motoring' started by Tom Schwartzmier, Aug 10, 2003.

  1. I am having difficulty passing my state mandated emission test on a 1990
    Dodge Spirit with a 3.0 V-6 engine. I recently acquired this vehicle which
    has only 32K original miles on it. It was brought in from out of state
    where it had not been required to be tested for emissions.

    The vehicle has obviously not been driven much but I have driven it for over
    500 miles so the gasoline in it was fresh. The station that performed the
    emission testing suggested a tune up which I am in the process of doing
    before I bring it back for a re-test. About all that can be replaced during
    a tune up is plugs, dist. cap, rotor and plug wires. I am also running
    gum-out fuel injector cleaner through it and then a product from CRC which
    guarantees that you will pass the emission test or they'll refund double
    what you paid for it.

    I can't help but wonder if there isn't something else that I should to
    correct this problem once and for all since it will have to re-tested
    annually and with such low mileage I might have this vehicle for several

    Any suggestions would be appreciated.
    Tom Schwartzmier, Aug 10, 2003
  2. What didn't pass? HC? NOx?

    In addition to what you mention above, I'd change the air filter and
    check the EGR valve. Could be the catalytic convertor is dead also.
    Knowing what failed will help isolate the problem. Different pollution
    control devices serve different functions. For example, EGR helps to
    knock off the high temperature spikes during combustion which reduces
    formation of oxides of nitrogen. High HC could be fuel injector
    problems, clogged air filter, faulty mass air flow sensor, water temp
    sensor, etc.

    There's lots of other things to check, but the more information as to
    what the failure mode was, the less random parts replacement you will
    have to do.

    Have you checked for fault codes? I'm not sure about the 3.0 engine,
    but my Acclaim with the 2.5L could be checked by cycling the ignition
    key as follows: on-off-on-off-on within something like a 5 second window
    and then counting the flashes on the check engine light. A long pause
    is a separator between digits and a short pause is a separator between
    pulses in a digit count. If memory serves, you should start with 12 and
    end with 55 and any real fault codes will be in between.

    Matthew S. Whiting, Aug 10, 2003
  3. Matt --

    Thanks for your input and help. I've enclosed some additional information


    It failed on both. The CO% was 9.44 and the limit is 1.20 -- the HC ppm
    was 638 and the limit is 220. Both or these readings were at an idle.

    It also failed both at 2,500 rpm test with readings of 8.59% and 281 ppm
    respectively. These are somewhat better but still not very close.
    The air filter was brand new. I'll have to check the EGR -- that's a good
    idea. I guess it could be catalytic converter. I am trying to run cleaner
    through the injectors -- it runs so smooth and well it's tough to imagine
    them being clogged.

    One thing I have noticed about the vehicle is that the water temperature
    gauge never goes up very far -- it barely evers goes into the low end of the
    operating range -- this is much lower than a previous Spirit I owned and the
    Jeep that I have now. Maybe the thermostat is too low or not closing
    tightly to allow the temperature to rise. You wouldn't happen to know what
    temperature this should be would you ? Probably either 180 or 195 would be
    my guess.
    I used to own an 1989 Spirit with a 2.5L turbo. I remember the trick with
    the codes. I'll have to give that a try -- I had forgot about this "trick"
    Tom Schwartzmier, Aug 10, 2003
  4. OK, CO isn't the same as NOx. I forgot to mention CO in my first post.
    NOx shouldn't fail at idle anyway.
    I'll add the oxygen sensor to the list of items above. Basically, it
    sounds like you are running too rich given the high HC level. Any
    sensor that provides mixture control input to the ECM is suspect.

    Could be a thermostat problem. Cool running could cause the problem you
    are seeing. I had the water temperature sensor fail on my Chevy truck a
    couple of years ago. The engine still warmed up fine, but the computer
    thought it was still cold. It ran it very rich which did wonders for
    power output, but gas mileage dropped by 40% and the exhaust pipe was
    black as could be. How does your tail pipe look?

    Matthew S. Whiting, Aug 11, 2003
  5. Matt --

    Thanks again for your help.

    The codes I got from rotating the key three times were 12 - 51 - 55. Code
    51 is related to the oxygen sensor. I don't believe the other codes pertain
    to a problem.

    See additional information below.

    NOx was not on the print out they gave me -- just CO and HC
    Since I got the error code 51 I think the oxgen sensor is one of the the
    first things that I'll replace.
    The thermostat is a cheap precaution and it's easy to get to so I plan on
    changing it for sure. I have no unusual black deposits on the exhaust pipe.
    Tom Schwartzmier, Aug 11, 2003
  6. Replacing sensors and other parts willy-nilly isn't the way to fix the
    problem. Proper diagnosis (starting with a readout of the fault codes) is.
    Except in cases of *extremely* rich running, tailpipe appearance is not a
    reliable indicator of combustion conditions in any car burning unleaded
    gasoline, with or without a catalytic converter.

    Daniel J. Stern, Aug 11, 2003
  7. I agree and said much the same thing earlier in the thread if you'd
    bothered to read it.

    Well, when my water temp sensor failed on my pickup, it was running
    extremely rich. I went from 17 MPG to 12 MPG.

    Matthew S. Whiting, Aug 11, 2003
  8. Usually, a stuck open thermostat will cause a "17" to be set.

    -Kirk Matheson
    Kirk Matheson, Aug 12, 2003
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