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Thread: Hesitation under load after head rebuild

  1. #1
    Join Date
    Nov 2017
    Location
    portland,or
    Posts
    174
    My Cars
    1982 320is /1973 2002tii

    Hesitation under load after head rebuild

    Sorry if this is a bit long by the way. So I just recently had my ’82 320i head replaced ( cracked) and now that its back it hasn’t been running great. It starts up fine, idles at around ~1000-1100, which I haven’t been able to get any lower. It rev’s decent while sitting, but it hesitates/ stutters under load. It also has a hard time accelerating on even the slightest incline. I had a similar issue a year or so ago and it was a cracked wire to the frequency valve, so this has been fixed.

    Things I’ve done:


    1. Reset timing to 25btdc at 2200rpm. Ball bounces around a bit, but I can see it enough with timing. I don’t know how much movement would be a problem.
    2. Adjusted fuel mixture with 02 sensor to ~ .4-.5v ( its not a steady number, so the best I could do)
    3. All new vacuum lines while head was off.
    4. I checked to see if Aux Air valve was working and seems to be. (open a bit when cold and closed when warm)
    5. Checked plugs ( a little black) but are newish. Cleaned and checked gap to .028-.03.
    6. Plug wires are new.
    7. Ignition coil is newish
    8. Rotor and cap are in good shape and pulled vac on advance ( by mouth) and it seems to work.
    9. Replaced fuel filter just in case
    10. Intank pump was replaced a year or two back.
    11. Main fuel pump has not been replaced.
    12. All gas tank fuel hoses are new and new premium gas in tank. The car sat a few months this winter while a new head was being sourced.
    13. Air filter looks good.
    14. Exhaust is old, but I cut open CAT when I had a clog, so I know that’s not the issue.


    Was hoping the new gas would smooth things out, but it didn’t. Was thinking Distributor or main fuel pump. Anything else I’m missing??

    Thanks, B
    Last edited by floatinghead; 03-10-2024 at 05:17 PM.

  2. #2
    Join Date
    Nov 2017
    Location
    portland,or
    Posts
    174
    My Cars
    1982 320is /1973 2002tii
    i think i found my answer. was checking the wiring around the frequency valve and it looks like while the head was being reworked, the wire got pulled out from the connector. so i guess the symptoms being similar to before wasn’t just a coincidence.

  3. #3
    Join Date
    Mar 2007
    Location
    Portland, OR
    Posts
    915
    My Cars
    80 320i, 87 325 i & is
    that’s easy! so is it better now?


    Sent from my iPhone using Tapatalk

  4. #4
    Join Date
    Nov 2017
    Location
    portland,or
    Posts
    174
    My Cars
    1982 320is /1973 2002tii
    Quote Originally Posted by Clio320i View Post
    that’s easy! so is it better now?

    Sent from my iPhone using Tapatalk
    I had some extra connectors from the last fix, so hoping to wire it in this evening, then take it for a drive. Fingers crossed.

  5. #5
    Join Date
    Feb 2024
    Location
    usa
    Posts
    17
    My Cars
    BMW
    Eager to see the result.

  6. #6
    Join Date
    Nov 2007
    Location
    Sacramento, California
    Posts
    4,704
    My Cars
    1980 BMW 320i E21 M10B18

    Cool

    If that does not fix it, I'd look into the Warm up Regulator and see if it's 20/50.


    Randy

  7. #7
    Join Date
    Nov 2017
    Location
    portland,or
    Posts
    174
    My Cars
    1982 320is /1973 2002tii
    well that was it. broken wire to the frequency valve. drives sooo much better. kinda like it should.

    now on to the next thing to fix.

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