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Thread: Bad Idle - help

  1. #1
    Join Date
    Jul 2008
    Location
    Indianapolis, IN
    Posts
    3
    My Cars
    85 M636 & 88 M6

    Bad Idle - help

    My 95 S50US (in an E30 M3) was running fine until the last session at Mid-Ohio. It starts and dies. If I run it at higher RPM it 'seems' OK. (but I haven't driven it much since unloading it off the trailer.

    I pulled the intake manifold off and cleaned the idle control valve and trimmed a kinked section of vacuum hose from the fuel pressure regulator.

    I replaced:
    fuel pressure regulator
    TPS (it gave me weird readings)
    Plugs

    No change. Idles rough - dies.

    I cleaned the MAF with the CRC sensor cleaner. I blew it dry and let it sit for a few days.

    I checked all clamps on vacuum hoses and they are tight. Upon refiring it -very loud BANG! A lot of smoke. It backfired and smoked like crazy UNDER the intake. I pulled the air filter off and smoke was pouring from the intake. (I thought it was an electrical short under the intake initially)

    WHAT!!??

    I'll pull the intake back off - but any ideas?

    Bad MAF? Cracked hose I overlooked? (the one from the intake to the idle control?).

    Help

    Thanks

    Chris
    Attached Images Attached Images
    Last edited by cw635; 09-14-2020 at 08:49 PM. Reason: found a huge hole

  2. #2
    Join Date
    Jul 2008
    Location
    Indianapolis, IN
    Posts
    3
    My Cars
    85 M636 & 88 M6

    I think I found the root cause!

    Ahhh - easy to miss if you don't spread the old hose open. Check this out! I hope (and really believe) this is the root cause!

    But why the huge misfire? That still concerns me. I'll pull it out in the driveway when I fire (no pun intended) it back up.......just in case
    Attached Images Attached Images

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