2002 winstar mystry scope pattern with rough idle | FordForumsOnline.com
  1. Welcome to FordForumsOnline! Our community is here to help you with any questions you have related to your Ford. If you are looking for a friendly community to hang out with other Ford owners you can look no further than our forums here! Registering is easy and free!

2002 winstar mystry scope pattern with rough idle

Discussion in 'Engine, Transmission/Axle & Driveline/Axle' started by jalinsta, May 7, 2020.

  1. jalinsta

    jalinsta New Member

    Joined:
    Aug 27, 2019
    Messages:
    3
    Likes Received:
    2
    2002 Winstar , code P305, Used regular electric repair scope to scope cylinder 5 using 5 v/div, 0.5 mil/sec with 10X probe and got the pattern included. It does not look like anything I have seen on line. Can anyone diagnose this pattern. Engine runs rough at idle, have done the usual things, replaced plugs, wires. coil, injectors and gaskets. Fuel pressure 32 #, cylinder 5 & 6 compression check, 120 #. This same pattern is on cyl. 4, 5, 6.
    I am a retired businessman and do my own auto repair work but this one has me stumped. Any help will be appreciated. This is my first post on this forum.

    Attached Files:

  2. Dominick 1

    Dominick 1 Well-Known Member Respected Member

    Joined:
    Dec 26, 2014
    Messages:
    6,318
    Likes Received:
    828
    Location:
    Parkersburg Wv
    Have you checked your IMRC runner bushings?
    Un plug your egr valve and take it for a ride
  3. Dominick 1

    Dominick 1 Well-Known Member Respected Member

    Joined:
    Dec 26, 2014
    Messages:
    6,318
    Likes Received:
    828
    Location:
    Parkersburg Wv
    Welcome to the Forum
  4. Dominick 1

    Dominick 1 Well-Known Member Respected Member

    Joined:
    Dec 26, 2014
    Messages:
    6,318
    Likes Received:
    828
    Location:
    Parkersburg Wv
    https://www.fordforumsonline.com/th...l-pack-heat-failures-misfires-when-wet.12162/
  5. Dominick 1

    Dominick 1 Well-Known Member Respected Member

    Joined:
    Dec 26, 2014
    Messages:
    6,318
    Likes Received:
    828
    Location:
    Parkersburg Wv
  6. Action

    Action Moderator Staff Member Respected Member

    Joined:
    Mar 22, 2014
    Messages:
    12,244
    Likes Received:
    1,385
    Location:
    Phoenix, AZ 85008
    Welcome to the FFO!
    Longtime member first post

    P0305 FORD - Cylinder 5 Misfire Detected
    • Faulty spark plug 5
    • Clogged or faulty fuel injector 5
    • Faulty ignition coil 5
    • Fuel injector 5 harness is open or shorted
    • Fuel injector 5 circuit poor electrical connection
    • Ignition coil 5 harness is open or shorted
    • Ignition coil 5 circuit poor electrical connection
    • Insufficient cylinder 5 compression
    • Incorrect fuel pressure
    • Intake air leak
    You have covered most of the causes for this code on the ignition side.

    You could have a faulty injector or a vacuum leak. The injector would be rare.
    A vacuum leak or unmetered air or a generally lean condition would be more common. A slight lean may impact all cylinders and #5 just happens to be the leanest hole.

    Fuel trim is controlled by the PCM. That trim is monitored a couple of ways. Cam/crank sensor and O2 sensor. The cam/crank sensors report positions of cam and crank. The PCM knows that a certain amount of rotation should occur after a compression cycle. If that does not occur a code can be generated.

    The PCM may fatten up the mixture to help the scenario. That is where the O2 sensor comes in. It check how much fuel is being burned. However as the O2 sensor ages the signal back to the PCM slows down. A slow signal may mean the PCM gets a signal from the O2 for a situation that has occur too far back in history.

    O2 sensors should be replaced every 100,000 miles as maintenance.

    A vacuum leak can not be over come by the PCM. A vacuum reading should be taken or spray around joints (manifold, throttle body or ???) to see if you have leaks. Correct as needed.

    Action
  7. jalinsta

    jalinsta New Member

    Joined:
    Aug 27, 2019
    Messages:
    3
    Likes Received:
    2
    Thanks for the info. I have viewed the video's. Engine is missing when at idle, you don't notice it when engine revees up. It idles about 1000 rpm's so I suspect a vacuum leak somewhere but I haven't found one yet. I ordered a scope that will be here tomorrow. I will check relative compression with the scope and if ok will pull the cowling so that I can get behind the engine and maybe I will find a vacuum leak.
    The EGR valve seems ok. When i apply vacuum to it, the engine slows down.
    The car has slightly over 100,000 on it and the O2 sensor was replaced a few K miles ago. Not sure where the IMRC runner bushings are, will check internet after this reply. Would it still miss at idle if the EGR ports in the intake manifold where plugged since the ERG valve should be closed at idle..?
  8. Action

    Action Moderator Staff Member Respected Member

    Joined:
    Mar 22, 2014
    Messages:
    12,244
    Likes Received:
    1,385
    Location:
    Phoenix, AZ 85008
    If the EGR valve is open to any degree at idle the engine can operate erratically. The valve is supposed to be closed at idle and just off idle. In addition should be closed during cold engine operation no matter what throttle position.

    A compression test is looking for combustion sealing. The condition you described could be a burned valve which would act like as you have described.

    On a warm engine the idle speed should be below 1000. If not either there is a vacuum leak (most common) or a engine control issue.

    Since you are getting a code that an intake leak is possible, I would pursue that line of diagnosis. A vacuum gauge may be a better tool to have than a compression tester. And in the world called perfect there is no such thing as not enough tools.

    >>>>>>>>>Action
  9. jalinsta

    jalinsta New Member

    Joined:
    Aug 27, 2019
    Messages:
    3
    Likes Received:
    2
    Thanks for all of the good advice. I found 3 things that needed repair or replacement. The intake manifold gasket had a small leak, the IMAC front rod was missing, and the hardest thing to find was an intermittant fuel injector plug.
    The engine now runs like new.
    Action and Dominick 1 like this.
  10. Dominick 1

    Dominick 1 Well-Known Member Respected Member

    Joined:
    Dec 26, 2014
    Messages:
    6,318
    Likes Received:
    828
    Location:
    Parkersburg Wv
    Thank you for Posting the results
  11. Action

    Action Moderator Staff Member Respected Member

    Joined:
    Mar 22, 2014
    Messages:
    12,244
    Likes Received:
    1,385
    Location:
    Phoenix, AZ 85008
    Interesting! Thanks for posting.

    >>>>>Action

Share This Page