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  1. #1
    Join Date
    Feb 2018
    Location
    Flourtown, PA
    Posts
    5
    My Cars
    2004 BMW X5 3.0

    Low Compression and Misfire

    Hi, I have researched my problem on this forum and watched tons of videos. I am ready to ask for help and opinions.
    Thank you very much in advance...

    The car is a 2004 X5 3.0 with 230k miles.
    I have not owned it long (a few weeks and less than 100 miles) and I got it cheap - and now know why.
    It drove fine for a few days (50 miles or so - various speeds)
    Noticed Oil was low and a little cruddy looking - added 2 Qts of new M1 Syn 0/30 to get it up to full. Planned on Oil Change in a few days.

    When driving the car - highway speed, the check engine light went on and the car started running rough.
    Misfire on Cyl 3
    Changed plugs (none looked too bad, no major oil, no major ash, etc. Changed to NGK 4-prong plugs.
    Changed coils - noticed that Cyl 4 coil was different but none looked bad, no oil or cracked boots, etc. Changed them all anyway.
    After coils and plugs, still running very rough and misfire on Cyl 3.
    Swapped a couple of coils and plugs to rule out bad coil/plug - no change
    Installed new Fuel injector on Cyl 3 - No Change
    Sprayed some ether around running engine to see if there was a vacuum leak - no engine speed up and don't see any cracked or bad hoses - prob need to look further.
    Compression Test on Cyl 3 - 30!
    Compression on 2 and 4 - Greater than 150 - did not test the others.

    Put scope down Cyl 3 - did not see any holes or anything on top of piston. Walls of Cyl looked good - no scars.
    I did not get to look at the valves because the mirror on the scope sucks and I did not want to fish it out of the cyl if it broke. Going to borrow a better scope to look at valves.

    I put Rislone in Oil and ran and drove the car - did not notice much difference
    I bought some of the blue (flat bottle) BMW branded injector cleaner and put a couple ozs in Cyl through plug hole and let it sit overnight.

    Just started it and ran in driveway. Lots of smoke from the treatment.
    After it cleaned out and stopped smoking, new compression test. Got 60.
    I just dumped some more of the blue cleaner in and will let it sit for the day and try again to see if it gets better.

    So not sure what to do next.
    Scope Valves?
    Remove Valve Cover and inspect springs and try to look at valves from top?
    Remove Head and get better look at valves from bottom, cyl and pistons?
    I can buy a leak-down tester and try that too?

    Other notes -
    The engine does not make any bad noises, you can hear the misfire but no mechanical noises, clanking, valve noise, etc.
    You can hear the timing and or vanos chain but not loud.

    Open to thoughts, suggestions and next steps.
    Again, thanks!
    Last edited by Rappo999; 02-07-2018 at 11:52 AM.

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