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Thread: 85 325e low mileage running really rough after sitting for a time

  1. #1
    Join Date
    Nov 2012
    Location
    Dallas, Tx
    Posts
    22
    My Cars
    1985 325e

    85 325e low mileage running really rough after sitting for a time

    Good morning. I have owned my 1985 325e for many years, and I consider it a collectable. It has less than 50,000 miles, documented and original. My problem is that the car sits for periods without being driven. I know, this is a no-no, however I have several cars and projects so I get to it when I can, promise. This particular car is really rather b*tchy, with switches, gauges, and even the crank sensor failing from sitting in a nice garage, covered, with no wild temperature swings. Oh well, we put up with things for the ultimate driving experience, right? Here is my question: The car is running really rough and I wondered if anyone has a ‘been there done that’ experience on something degrading from just time before I dive into this thing with both feet. I would be really grateful for any assistance so that I don’t chase my tail on illogical troubleshooting. For instance, I read in the searches that I did about vacuum hoses, ICV, and such, but these don’t seem likely given the low mileage and the fact that the car ran perfectly when last driven. She starts up just fine, but feels as though 4 or 5 of the 6 cylinders are firing. I thought it may clear, but it did not upon warming the car up, although not fully to operating temperature. I hate to fuss around with the injector connectors, since I read that they are rather brittle, and I can’t see an intake plenum just cracking on its own accord, but I have been wrong many, many times before. I am really just looking for wisdom and experience to arm myself for this weekend.

    Thanks for any help, sincerely.

    Ed Fisher
    Dallas, Tx

  2. #2
    Join Date
    Dec 2004
    Location
    Huntsville, AL
    Posts
    25,923
    My Cars
    87 325is
    Age takes it's toll on rubber & plastic part, so even though the car has low mileage those parts degrade with time. An 85 is now 27 years old. Which means that it is three year shy of the point that the 4th replacement of the entire cooling system, all fuel & intake hoses, ignition wires, and distributor would be scheduled. And just based on time it would be three years shy of it's 8th timing belt.

    A smoke test will tell if there are intake leaks. The ignition stuff (and plugs) you can simply change.
    The car makes it possible, but the driver makes it happen.
    Jim Levie, Huntsville, AL

  3. #3
    Join Date
    Nov 2012
    Location
    Dallas, Tx
    Posts
    22
    My Cars
    1985 325e
    Thank you for the reply. I am aware of the vagaries that can result from age-related plastic and/or rubber degradation. However, I also know that one must consider thermal cycling, UV exposure, and contamination of fluids, wear, and other factors when judging whether a component, either organic or inorganic, is likely to fail. Simply changing out items that have been static in an enclosed environment is not what I was hoping for in my post, but again, thank you for your reply. Rather, I had hoped for a ‘check here first as this piece, part, connection, etc is a likely place to start’.

    Regards,

    Ed Fisher
    Dallas, Tx

  4. #4
    Join Date
    Nov 2006
    Location
    Winston Salem NC
    Posts
    21
    My Cars
    91 318IS,328I,Z3 Coupe
    My son had a 89 I a few years ago we bought with this same [kind of] problem. It would skip after parking over night but was fine if restarted after a hour or so. It would clear up after a minute or so when started. The fuel pressure would fall VERY slowly after turning it off. I pulled the fuel rail, laid it on the intake, just jumped the pump relay and watched. #6 injector just got a little wet, then started to drip just a little. I had already heard air being purged out by the regulator when messing with it before, checking pressure and stuff. For some reason there would be air enter the fuel rail over night through this injector. I know it's weird and I have never seen it before or since and I've been a mechanic for 40 years. Had the injectors cleaned and it was fine until he sold it a few years later. I would check fuel pressure and see how long it holds. You didn't say if it was a dead skip [one cylinder dead] or was random. Also pull the plugs and just look at them. If it sets a lot, carbon will break loose in the cylinder and bridge the plug causing a shorted plug. If you see anything between the electrode and grounding arm clean it out and see what happens. Good luck

  5. #5
    Join Date
    Nov 2012
    Location
    Dallas, Tx
    Posts
    22
    My Cars
    1985 325e

    weekend

    Thanks for that input Lugerhead. This is good information whether on this car or others and I appreciate it. I hope to get out there this weekend, although I had hoped a nasty burn on my left hand would be farther along in the healing process by now, and I will report back any findings as soon as I discover something definitive. Thanks again.

    Ed Fisher
    Dallas, Tx

  6. #6
    Join Date
    Nov 2012
    Location
    Dallas, Tx
    Posts
    22
    My Cars
    1985 325e

    rough running remedied

    I thought I would post the resolution of my rough running, low mileage, 1985 325e. I started by verifying that all six plug wires had spark, as evidenced by an inductive timing light pickup. They did. Next, I pulled the plugs and 1-5 looked perfect, #6 was blackened and sooty. This led me to believe that an injector wasn’t working correctly for that hole. I put the cleaned plug back in and started the car and held it steady at 2500 rpm’s for about 30 seconds and I could hear the engine miss abating and the revs smooth out. The car was clearing it’s throat. I shut her down after ensuring that it was running and idling on all 6 and prepared to get it out of the garage and take it for a spin. Once prepared to leave the car would not start. I then turned battery charger to 40 amp start mode and she fired up easily. I went to the store and purchased a new battery, filled the tank, added the “Chevron with Techron fuel injector cleaner”, had the car inspected, and took her for a nice long, drama free, drive.

    Almost drama free, as the sunroof switch isn’t happy now. Does anyone have any advice on how to sneak that out of the headliner hole so that I can properly clean it?

    Thanks for the help offered, the BMW is happy again.

    Incidentally, I am a huge fan of the injector cleaner mentioned above. It comes in a black container and Wal-Mart actually carries it now. It solved a no-compression/low-compression fail on a 1985 Camry once after it was recommended to my by a 25+ year Toyota tech. The intake valves had cooling flutes on them and would carbon up and stick. Chevron injector cleaner fixed it and the problem never returned, though I would add a container every 30K miles or so. You hate to get stranded calls from the wife if you can prevent it

    Ed Fisher
    Dallas, Tx

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