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Thread: Extremely rough idle no codes

  1. #1
    Join Date
    Sep 2023
    NS, Canada
    My Cars
    1996 BMW 318i Cabrio

    Extremely rough idle no codes

    So I made a post here a few days ago but this one is an update.

    I purchased a manual 96' 318i convertible (m44 engine), and it's had a super rough idle since I've had it. It sounds like it's cammed and it's a rhythmic feeling like a misfire. I don't have any codes popping up other than P0130 and P0135 which are stored.

    First, I pulled the plugs, and they seemed fine and dry. I pulled the ICV and cleaned it. When I took off the oil fill cap, the idle dropped but there was no suction, and the pressure shoots into the atmosphere. I'm not sure if this is a sign of a working or broken CCV. When I unplug the MAF, the car bogs down for a few seconds, and the idle goes back up to the same rough idle. I also cleaned the battery terminals and connectors. I did a DIY smoke test through two different hoses but didn't see anything, but I'm not sure if this was cause my machine wasn't strong enough, or if there were no leaks.

    I replaced a few vacuum hoses cause they were completely cracked: the distribution hose with the four hoses connected to it, the hose going from the CCV to the valve cover, and the intake hose that connects from the boot to the distribution piece.

    I ordered a valve cover gasket, NGK plugs, and a fuel filter but they haven't arrived yet.

    Note that the car runs fine while I'm driving it, but the idle is horrible. Sometimes when I'm coasting in neutral or at a stop, the idles drop super low and it feels like I have to keep the revs up manually to keep it from stalling. I believe this car has power steering issues because it makes a different type of vibration at full lock to the right... not left though. I don't think it would be the engine mounts because although the engine is visibly shaking like crazy, there are no odd vibrations while I'm driving.

    On very rare occasions at idle, the rpm drops to below 100 and then catches itself shooting back up to 1500, then back down to 750.

    It's very nerve-racking driving this in traffic so I'm hoping to get a solution or tips from someone here.

    Thank you

  2. #2
    Join Date
    Jun 2010
    My Cars
    1997 328i
    Put a bottle of royal purple complete fuel system cleaner and couple gallons of premium gas, drive it.
    Attn. NEWBIES: Use the search feature, 98% has already been discussed.
    Click the search button, select "search single content type", select the "e36 sub forum" specifically, try the "search titles" then try the "search entire posts".

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