2004 RANGER 3.0 misfire cylinder 4

Discussion in 'Explorers - Expeditions - Excursions - Broncos -Es' started by OLD N IN THE WAY, Nov 15, 2020.

  1. OLD N IN THE WAY

    OLD N IN THE WAY Junior Member

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    In May of 2019 I relocated to Denver from Tulsa. When I got here I had problems with the check engine light coming on and staying on. I would check it at O'Reilly's and it is always Cylinder 4 misfire. I changed the cylinder 4 plug and wire, no change. I then changed the cap and the coil block and all wires but it stayed on...for a while. Then one day it went off after a few weeks. I drove it to Tulsa, no problem. On the way back to Denver, half way across no mans land it came on again and stayed on till we reached Denver. It stayed on a few weeks more, then it went off and stayed off about a year. Here sometime last week it came back on. I checked it and again Cylinder 4 misfire. The light remains on since it came on. Is it really misfiring? What's UH da deal?

    Frustrated!!
     
  2. Roush PSD Interceptor

    Roush PSD Interceptor Straight Piped Diesel Staff Member

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    TSB 05-26-3

    FORD: 2004-2006 Ranger

    ISSUE
    Some 2004-2006 Rangers 3.0L-2V "Vulcan" vehicles may exhibit:
    - Malfunction indicator lamp (MIL) on with diagnostic trouble codes (DTCs) P0300-P0306 and P0316
    - Rough running at various RPM
    - Rough idle
    - Misfire

    ACTION
    This may be due to an engine exhaust valve seat recession causing a loss of compression. Refer to the following Service Procedure to diagnose exhaust valve seat recession.
    SERVICE PROCEDURE
    1. Perform a power balance rest to clarify if a cylinder is misfiring. Identify and keep record of any cylinder that has a concern.

    2. Perform a manual compression test with the spark plugs removed to locate any cylinder that may have low compression. Refer to the appropriate Workshop Manual, Engine System, General Information, 303-00.

    3. If no low compression is found per shop manual instructions, proceed with normal misfire diagnostics per the Powertrain Controls/Emissions Diagnosis (PC/ED) Manual for the appropriate model year.

    4. If low compression is found and it is a cylinder that had a misfire on power balance, perform a leakdown test to determine the source of leakage that may be causing the low compression. Refer to the appropriate Workshop Manual, Engine System, General Information, 303-00.

    5. If low compression is found in a cylinder that did not have a misfire detected then proceed with normal base engine diagnostics per the Workshop Manual, Engine System, General Information, 303-00.6.

    If the exhaust valve is identified as the source, replace both cylinder heads with the newly released service cylinder heads. Refer to the appropriate Workshop Manual, Section 301-01A.

    PART NUMBER / PART NAME
    6U7Z-6049-A / Cylinder Head Assembly

     
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