Rough cold idle - Warm up and control pressure regulator? | FerrariChat
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Rough cold idle - Warm up and control pressure regulator?

Discussion in '308/328' started by JR328, May 18, 2009.

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  1. JR328

    JR328 Rookie

    Sep 8, 2008
    23
    Chicago area
    Full Name:
    John
    #1 JR328, May 18, 2009
    My car ('89 328) has a very rough idle warming up. The idle is low (~600 rpm) and runs very rich until warmed up. I believe my warm up and control pressure regulator is the problem (not 100% of this). If this is the problem how does this device work and how do I fix it? Tonight, I will inspect fuse #9 cold start electro-valve to make sure this is not the culprit. Please help, and/or direct me to a previous thread with this topic. Thank you, John in Chicago
     
  2. Iain

    Iain F1 Rookie

    Jan 21, 2005
    3,354
    UK
    #2 Iain, May 18, 2009
    Also start looking for vacuum leaks. The warm up cycle on the KJet will not work properly unless the system is sealed. Also check your throttle body is working properly & that the butterfly is closing. If not the thing idles too high & then you adjust the bypass valve down to compensate & then the whole thing is out of whack etc etc etc.
     
  3. JR328

    JR328 Rookie

    Sep 8, 2008
    23
    Chicago area
    Full Name:
    John
    #3 JR328, May 22, 2009
    Iain, thank you for the comments. I will check for vacuum leaks this weekend, plus look at the throttle butterfly position. The fuse checked out OK. If all is fine, then I think the culprit is the regulator. I just purchased a Bosch fuel injection manual, from Amazon, to dive into the fuel injection system next week. John
     
  4. MarkCollins

    MarkCollins F1 Rookie
    Owner

    Jul 2, 2002
    3,202
    South England
    Full Name:
    Mark Collins
    #4 MarkCollins, May 22, 2009
    JR

    I went through a similar process recently, I believe he primary problem with mine was that the air sensor plate below the air filter not closing properly.
     
  5. doug328

    doug328 Formula 3

    Mar 11, 2004
    1,599
    The Space Coast, FL
    Full Name:
    Doug B
    #5 doug328, May 23, 2009
    The throttle body stays closed while the 328 is idling. The idle rpms are adjusted by the large set screw located down low on the metal pipe that comes off the fuel metering unit. Idle air goes into the intake plenum via the 2 rubber hoses leading off to the side. One goes directly into the plenum and supplies the air when the engine is warm and the other goes to the aux air valve located under the little coolant tank. The aux air valve is open when cold to allow more air to the engine, once the engine warms up that valve closes and shuts off the extra air. If you engine is running at such low rpms then mabe this aux air valve is not working (ie; stuck closed). Easly to take out and check. sometimes just spraying a little WD-40 in the opening and using a little screwdriver to move the sliding plate is enought to get it working. You can always test it by putting it in the freezer for about 10 minutes and looking at the sliding plate (should be most of the way open) and then putting it in the oven at about 150 degrees for a couple of minutes to see if the plate moves. If it doesn't then you will need a new one. Good luck.
     

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