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2004 Chrysler Van 3.8L Misfire P0306 “Need Some Direction”

Home Forums Stay Dirty Lounge Service and Repair Questions Answered Here 2004 Chrysler Van 3.8L Misfire P0306 “Need Some Direction”

This topic contains 4 replies, has 3 voices, and was last updated by Chris Garland Chris Garland 9 months ago.

  • Creator
    Topic
  • #895591
    Chris Garland
    Chris Garland
    Participant

    Ok I am reaching our for some more experienced advise. Love the ETCG channel and new to the website and forum.

    Customer brought in a 2004 Chrysler Grand Caravan wanting oil change and filter and DTC checked out
    Code was P0306 with rough idle and O2 sensor Heater code
    Customer had already changed the spark plugs, wires and coil.

    I replaced the O2 sensor and #6 injector after checking below listed items

    I started by rechecking all those by moving spark plugs ( No Change)
    Moved wires ( No Change)
    Checked Spark at coil and wire (Spark good at both ends)
    Checked Signal from PCM with test light (Good Signal)
    Completed Compression check all cylinders was 160-170 psi
    Completed Leak down on #6 with only 10% leak
    Completed leak down on #2 and #4 also with same results
    Checked for vacuum leaks with propane (Nothing noted)
    Checked manifold vacuum with gauge and was within normal ranges

    I can’t find any issues with Spark, Fuel or compression

    Not sure what to check next
    My thought is electrical however if it is a spark issue why am I not seeing an issue with the companion cylinder misfiring also.
    I don’t think its Fuel Pressure issue as its only one cylinder misfire.

    Any advise would be greatly appreciated.

Viewing 4 replies - 1 through 4 (of 4 total)
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  • #895592
    Nightflyr *
    Richard Kirshy
    Participant

    I started by rechecking all those by moving spark plugs ( No Change) Did you check for proper gap?
    Moved wires ( No Change) Did you check wire resistance?
    Checked Spark at coil and wire (Spark good at both ends) Did you check secondary ignition wave form with a scope?
    Checked Signal from PCM with test light (Good Signal) Did you check it under load?
    [color=red]Completed Compression check all cylinders was 160-170 psi
    Completed Leak down on #6 with only 10% leak
    Completed leak down on #2 and #4 also with same results[/color] Did you try a relative compression test?
    Checked for vacuum leaks with propane (Nothing noted) Did you try smoke testing the system?
    Checked manifold vacuum with gauge and was within normal ranges

    It would appear you will need to do further in-depth diagnostics with a scope and test equipment.

    I don’t think its Fuel Pressure issue as its only one cylinder misfire. is it a single or dual fed fuel rail?
    If it’s a single fed loop and #6 is on the end of the loop.
    Low fuel pressure may be starving the last injector.
    Some food foe thought.

    #895594
    Chris Garland
    Chris Garland
    Participant

    I did check gap and were all good

    I will be checking wire resistance

    Unfortunately dont have scope yet to check secondary ignition.

    Checked signal at idle and under load both good.

    Unfortunately no scope for relative compression test

    I did not smoke test but will try that when i go back to work.

    It is a dual rail fuel system with #6 on the end. I will run a pressure gauge to verify pressure.

    I have really wanting to add a scope seen some of the great tests it does. Its crazy when i talk to other local mechanics and tool truck guys how many say NOBODY USES SCOPES. Thats why I want to add so i can be the go to guy to get stuff diagnosed. Way to many parts changers in my town.

    Thank you so much for the tips.

    #895609
    Zayne Ali
    Zayne Ali
    Participant

    This might be far fetched a bit. Seems like you’ve exhausted your look into it. But maybe an early head gasket leak might be occuring?

    #895614
    Chris Garland
    Chris Garland
    Participant

    Thank you for the post. I didn’t see any signs of head gasket leak. Spark plug was not overly clean and all the leak down test were good. Also no issues with overheating.

Viewing 4 replies - 1 through 4 (of 4 total)

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