+ Reply to Thread
Results 1 to 6 of 6
  1. #1
    Registered Member
    Location
    , ,
    Member No: 41841 MikeM745 is an unknown quantity at this point MikeM745's Avatar
    Join Date
    Jul 2002
    Posts
    17
    Rep Power
    0


    Yes | No

    745 running rough after warm up

    My 84' 745 has been acting like is is running out of gas when under power and warmed up. At idle everything seems fine. It starts up like normal but once it warms up and on the road it begins to lose power and will backfire if I press down on the throttle all the way. If I feather it a little it will seem to get more power eventually. Fuel pressure is 30-32 psi constant. Even if I hit the throttle pressure doesn't go way up. I need advice on what to look for.

    Mike


  2. #2
    KevinD
    Guest
    Location
    , ,
    Member No: KevinD's Avatar


    Yes | No

    Re: 745 running rough after warm up

    I assume that was your post on [Oops!] (old fuel).
    If fuel change out doesn't resolve it, then always start looking for the maintencance items that require more frequent attention. Not sure how it idles after warm up. If idle is good then I would check the items that could cause the AFM flapper door to not respond when the throttle body is opened: specifically the the fresh air inlet hose out of the turbo, the charge air hoses at the inlet snorkel. Also make sure AFM door is not sticking. Every two years, you should remove, clean all engine electrical connections to AFM, CTS, TTS, TPS, Idle module, turbo cooling fan timer module, etc. Every year check all vacuum hoses.

  3. #3
    Registered Member
    Location
    Carlsbad, CA, United States
    Member No: 41018 ray_abreu is an unknown quantity at this point ray_abreu's Avatar
    Join Date
    Jul 2002
    Posts
    1,866
    Rep Power
    0


    Yes | No

    Check air boot THOUROUGHLY for cracks

    Ray 745-635-M635

  4. #4
    Registered Member
    Location
    Marietta, GA, United States
    Member No: 123311 JStein is an unknown quantity at this point JStein's Avatar
    Join Date
    Mar 2005
    Posts
    600
    Rep Power
    0


    Yes | No

    Bad fuel press reg

    w/ no manifold vacuum, you should have fuel press in the high 30s to low 40s depending on if you have a 2.5 or 3.0 bar FPR.

    at ~16-18 inhg manifild vacuum, you should have ~28-32 psi dependingon FPR rating.

    When cold, it is 'running ok' because the Motronic is in the warm-up mode..... js

    John Stein
    85 745 @ 1.2 bar
    85 M635CSi

  5. #5
    Registered Member
    Location
    Marietta, GA, United States
    Member No: 123311 JStein is an unknown quantity at this point JStein's Avatar
    Join Date
    Mar 2005
    Posts
    600
    Rep Power
    0


    Yes | No

    Also check......

    the idle air tube. they only last about 3.5 years. They are a PITA to change, but it is just one of those things ya need to bite the bullet and do.

    Item #3John Stein
    85 745 @ 1.2 bar
    85 M635CSi

  6. #6
    A Angel
    Guest
    Location
    , ,
    Member No: A Angel's Avatar


    Yes | No

    Re: 745 running rough after warm up

    Crack open that afm and check carbon track! If it has two lines worn through it bend the tab over to a fresh spot CARFULLY!

+ Reply to Thread


Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

     

Bookmarks

Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
1e2 Forum