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Thread: 98 740il Shifting Issue

  1. #1
    Join Date
    Sep 2018
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    98 740i Black on Tan T&A

    98 740il Shifting Issue

    I have a 98-740 in very good to great condition. Millage is 200k but the as with most of these cars the maintenance has been spot on. The car has one issue , when driving and I take my foot off the pedal or going down a hill the car wants to shift into overdrive, once the pedal is depressed all is fine. I have the fluid and filter changed and the tranny inspected by a transmission garage who said all looked very good , little shavings on magnets. What issues besides the transmission could be causing this? As I said at all other speeds the car runs and drives great. Any assistance is appreciated.

    - - - Updated - - -

    I just found this on the awesome forum,,, May cause improper shifting. Erratic downshift when coasting or slowing down. --- Clogged Cat's , this is the exact problem I am having!

    https://www.bimmerforums.com/forum/s...f-clogged-cats


    Now this had crossed my mind because I also here slight sputtering when accelerating but there are NO exhaust leaks,,, food for thinking.
    Last edited by nehinc; 09-16-2018 at 09:03 PM.

  2. #2
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    Sep 2018
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    98 740i Black on Tan T&A
    Ok I brought the car in with the intention of changing the cats, the mechanic said they were cool to the touch , no color change as is normal with bad cats , he did say there were two different types of cats on the car , one round and one oval. The car looks and runs perfect except for this going into OD at low rpm like stop signs or going down a hill, any ideas appreciated. Has anyone heard of this issue b4.

  3. #3
    Join Date
    Jun 2002
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    Aberdeen, NC (yes, again)
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    E39M5, E500 4WD
    Welcome to the forum, nehinc.

    I think we need to ascertain your interpretation of the word "overdrive".

    Overdrive is, specifically, the use of a gearset which delivers a ratio greater than 1 to 1.

    " a gear in a motor vehicle providing a gear ratio higher than that of the drive gear or top gear, so that engine speed and fuel consumption are reduced in highway travel."


    Therefore, it would be absolutely normal for your transmission to select "overdrive" or the highest possible ratio (lowest numerically) under the circumstances you describe.

    My feeling, though, is that you're using the wrong word to describe your situation. In colloquial use, overdrive is probably one of the most grossly abused automotive terms.

    Please describe what you mean, without using the word overdrive.

    And, by the way, catalytic convertors should NEVER be "cool to the touch" unless the car has been parked for hours. These devices operate at EXTREME temperatures; if they're not hot during operation, there is something VERY WRONG.

    However, I must warn you that bad catalysts are quite rare, but often misdiagnosed. DO NOT rush into buying cats!!!

    You need to take your car to a BMW specialist shop, and let them read all the codes in all the computers, as well as looking over the car and making you a list of what's wrong with it.

    Contrary to your assumption, the vast majority of these cars are GROSSLY neglected, and desperately in need of overdue maintenance and repairs.

    Chris Powell
    Racer and Instructor since, well. decades, ok?
    Master Auto Tech, owner of German Motors of Aberdeen
    BMWCCA 274412
    German Motors is hiring ! https://www.bimmerforums.com/forum/s...1#post30831471

  4. #4
    Join Date
    Jul 2011
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    2018 BMW M240i
    Cats that go bad are typically partially blocked. That is, the back pressure is too great. If the shop suspects that the cat is bad, the tech needs to remove the 2 O2 sensors and check the pressure differential. It should be less than 1psi.

  5. #5
    Join Date
    Sep 2018
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    98 740i Black on Tan T&A
    OK Back, one cat was falling apart , heard the death rattle , ok cats replaced , power back (oh yes),,BUT I still get the gear searching when coasting , down a hill the car will pull back or surge , at stop sign the car wants to move , it should not move unless I depress the throttle when level,? Yes? I was thinking of trying a cheap fix first the TCM , they are fairly cheap. So many moving parts in these drive trains ,,so many things to go wrong ,
    P.S. the reason I did not post or answer is the car is stored from Nov 10 until May1st due our INSANE winters. ANY IDEA ON WHAT IS CAUSING THIS ISSUE , the car is near mint so I will swap tranny's if I have to but if this is a fixable issue ?????

  6. #6
    Join Date
    Feb 2009
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    KC North, MO, USA
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    1996 740iL
    Still may be unrelated to your transmission. Example; a dying MAF can cause this car to give hard downshifts when slowing down and may even surge, then die, when coming to a stop. You need a proper diagnostic scan.

  7. #7
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    Ok will try that next ,thanks

  8. #8
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    Scan shows nothing , this issue could be explained as : coasting downshift/upshift --- free coasting erratic gear changing -- idle is high enough to move car with no foot on peddle , runs fine when depressing the peddle and driving at higher speeds, the issue only happens when coasting between 10 to 35 mph or coming to stop sign, almost seems like a jake break

    very annoying

    MAF cleaned
    tran fluid and filters all changed
    shows no codes on scan


    what items in this car control shifting at lower speeds ?

  9. #9
    Join Date
    Jul 2011
    Location
    Arlington, VA
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    2018 BMW M240i
    When you write that there are no codes, did you mean that the automatic transmission computer (EGS) showed no codes? What tool was used to scan the engine computer (DME) and the EGS?

  10. #10
    Join Date
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    98 740i Black on Tan T&A
    The issue is when coasting from 30 to 0 the car will gear search , it is very noticeable, a car should coast freely when not depressing the gas pedal, when below 10 mph and at night the headlights will dim slightly when it happens , before dumping more money into this car I am looking for input and ideas. I want to sort out if this is a transmission issue or something else, so I guess has anyone else had this issue?

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