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1990 Jeep Cherokee Question: Jeep failed emissions. What else can I do? see below



camarokid69ss, 4.0L 6 Cylinder, Denver, CO, January 17, 2014, 14:27

Failed the HC GPM. 3.7797 Limit 3.0000
Failed CO GPM 57.8648 Limit 25.0000
Before test I had spark plugs, spark plug wires, cap and rotor, new air filter, changed oil, and new oil filter.

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  • Answer #1

    cardocIII from Gillespie's Auto Service, January 17, 2014, 17:42

    It's running too rich. It's just barely over the HC limits, so the next thing to see is the lambda calculation so that we can see if the fuel is in control going into the engine. One of the key points about the lambda calculation is we also need the CO2 reading and the O2 reading along with the CO and HC. With that information I could tell you if the convertor is working or not. If you have O2 making it out the tailpipe with the numbers you posted then the catalyst becomes suspect.

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    camarokid69ss, January 18, 2014, 12:33

    Thanks for the help. Here are all the readings, limits, and results below on the paper they gave me:
    HC GPM 3.7797 3.0000 FAIL Catalytic Converter Presence PASS
    CO GPM 57.8648 25.0000 FAIL Air Injection System Presence N/A
    CO2 GPM 351.7844
    NOx GPM 2.0821 5.0000 PASS Oxygen Sensor Presence PASS
    Gas Cap Presence PASS
    Gas Cap Integrity PASS
    I hope the above readings help.
    Waiting for your reply.
    Thank you again!

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