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Thread: Why am I getting only 25mpg?

  1. #1
    WineGuyD wineguyd's Avatar
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    Why am I getting only 25mpg?

    I have a 1996 R1100R that I recently purchased with 17,000 miles on it. Took it to the nearest BMW service shop and had them do a combined 16/24k maintenance that included replacing all fluids, all filters, the plugs, the ribbed V-belt. They synced the TB and tuned and adjusted everything and anything possible. Conti Road Attacks are new with about 1k miles on them, wheels are balanced and true. Brakes in great shape with lots of life left on pads. I've been using 91-93 octane gas. And finally the bike has the stock OEM windscreen.

    In theory the bike should be running in top form now, the specs say I should get an average of 45mpg. When I first got it I went through three tanks of gas and averaged low 30's per gallon, Fuelly.com shows people getting no less than 35mpg and as much as 50mpg. With the bike back and tuned I've done two tanks and averaged 25mpg per tank.

    Any ideas as to why such low numbers? I commute on the bike so it gets mixed highway and city riding and I'm not a racer, nor do I gun it or rev it high. I plan to take it back to the shop but I'd like to be as informed as possible beforehand so if they try to blow it off I can respond to them.
    Purveyor of fine wines & spirits
    Rides a 1996 R1100R

  2. #2
    Registered User roger 04 rt's Avatar
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    That's really low.

    What coding plug is installed?
    Do you have any add-ons like a Power Commander or Techlusion?
    RB

  3. #3
    WineGuyD wineguyd's Avatar
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    Quote Originally Posted by Roger 04 RT View Post
    That's really low.

    What coding plug is installed?
    Do you have any add-ons like a Power Commander or Techlusion?
    RB
    By "Coding plug" do you mean spark plugs? BMW installed what ever they considered OEM stock.

    No add-ons.

    The bike seems to runs smooth, no missing or stalling. Starts up easy. I'm clueless as how this bike should feel and run since I've only owned Honda 4's previously. My first boxer.
    Purveyor of fine wines & spirits
    Rides a 1996 R1100R

  4. #4
    Registered User dieselyoda's Avatar
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    Here we go, this will be an awesome thread to follow. With all the "experts" to way in, I can't wait to see how far astray they will take you.
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case)
    1986 K75S(the beutch), 1993 K1100RS (blown engine), 1997 Chev Short Box (4x4 with an LT1)
    "Life isn't about how fast or how high, it's about how well you bounce."

  5. #5
    WineGuyD wineguyd's Avatar
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    Quote Originally Posted by Dieselyoda View Post
    Here we go, this will be an awesome thread to follow. With all the "experts" to way in, I can't wait to see how far astray they will take you.

    I'll take it!
    Purveyor of fine wines & spirits
    Rides a 1996 R1100R

  6. #6
    Moondog
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    Can you say 90 mph all day?

    (I jest)

  7. #7
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    25 is just a bit low...

    My RT still gets 30 if I run 90-110mph all day. Which it will happily do. Until I get caught.

    Aerodynamics on any bike are about the same, which is to say "bad" - windscreen changes have precious little impact.
    ditto tires - if you were running them soft enough to impact mpg they would self-destruct in short order.

    If it is running very nicely with no low speed complaints I would venture to say you are missing your coding plug.
    Or, your O2 sensor is actually bad or unplugged. (if unplugged for very long it might get damaged, so same thing really)

    With your religiously OEM, low mileage, unmodified status - I'd actually lean toward a bad O2 sensor.
    Rare but certainly possible given the age of the bike.

    I know they are a little on the spendy side so if someone knows how to test it?

    What either of these conditions will do is force the fueling logic out of closed loop mode.
    In closed loop it uses the O2 sensor to detect unused oxygen entering the catalytic converter.
    The ECU leans the fuel ratio out until there is some unused oxygen, which ensures that the converter can complete the combustion process.

    Also considering the age of the bike, please consider replacing your brake hoses.

    p.s. Man that's a good lookin' bike.
    Last edited by scott.lambert; 07-14-2013 at 02:28 PM. Reason: p.s.

  8. #8
    WineGuyD wineguyd's Avatar
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    Quote Originally Posted by scott.lambert View Post
    25 is just a bit low...

    My RT still gets 30 if I run 90-110mph all day. Which it will happily do. Until I get caught.

    Aerodynamics on any bike are about the same, which is to say "bad" - windscreen changes have precious little impact.
    ditto tires - if you were running them soft enough to impact mpg they would self-destruct in short order.

    If it is running very nicely with no low speed complaints I would venture to say you are missing your coding plug.
    Or, your O2 sensor is actually bad or unplugged. (if unplugged for very long it might get damaged, so same thing really)

    With your religiously OEM, low mileage, unmodified status - I'd actually lean toward a bad O2 sensor.
    Rare but certainly possible given the age of the bike.

    I know they are a little on the spendy side so if someone knows how to test it?

    What either of these conditions will do is force the fueling logic out of closed loop mode.
    In closed loop it uses the O2 sensor to detect unused oxygen entering the catalytic converter.
    The ECU leans the fuel ratio out until there is some unused oxygen, which ensures that the converter can complete the combustion process.

    Also considering the age of the bike, please consider replacing your brake hoses.
    Thanks Scott..All great points! I definitely plan to bring up the coding plug and O2 sensor in the conversation. As I mentioned earlier, I don't race the bike and have never passed 75mph(true mph, not speedo reading).
    Purveyor of fine wines & spirits
    Rides a 1996 R1100R

  9. #9
    Just me rad's Avatar
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    I have owned 5 different Oil heads and the only time I experienced MPG that low was when my TPS needed to be reset due to being bumped by my leg or foot. Oh ya, there was one other time, when I forgot to put the caps back on the TB's after a TB sync

    No question something is wrong. My guess is that it will be a simple fix...... once you find the problem.

  10. #10
    All-round Motorcyclist MarkM's Avatar
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    Quote Originally Posted by wineguyd View Post
    By "Coding plug" do you mean spark plugs? BMW installed what ever they considered OEM stock.
    Not spark plugs. He's referring to the Cat Code Plug. You can Google that and find some info about where it is located and that if removed, it can cause significantly lower gas mileage. I don't have any personal experience with it so I'll leave it at that. Maybe someone more knowledgeable will come along and provide more info specific to your bike.

    By the way, you'll find some good technical info about oilheads on IBMWR's Oilhead Tech Articles page. My favorite resource there is the R11xx Tune Up Manual.

    Good luck and enjoy the ride!
    Mark M, St. Louis, '95 R1100RS, '01 Super Sherpa
    There are two roads in life; the twisty one is vastly more fun.

  11. #11
    Registered User roger 04 rt's Avatar
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    Quote Originally Posted by scott.lambert View Post
    25 is just a bit low...

    My RT still gets 30 if I run 90-110mph all day. Which it will happily do. Until I get caught.

    Aerodynamics on any bike are about the same, which is to say "bad" - windscreen changes have precious little impact.
    ditto tires - if you were running them soft enough to impact mpg they would self-destruct in short order.

    If it is running very nicely with no low speed complaints I would venture to say you are missing your coding plug.
    Or, your O2 sensor is actually bad or unplugged. (if unplugged for very long it might get damaged, so same thing really)

    With your religiously OEM, low mileage, unmodified status - I'd actually lean toward a bad O2 sensor.
    Rare but certainly possible given the age of the bike.

    I know they are a little on the spendy side so if someone knows how to test it?

    What either of these conditions will do is force the fueling logic out of closed loop mode.
    In closed loop it uses the O2 sensor to detect unused oxygen entering the catalytic converter.
    The ECU leans the fuel ratio out until there is some unused oxygen, which ensures that the converter can complete the combustion process.

    Also considering the age of the bike, please consider replacing your brake hoses.

    p.s. Man that's a good lookin' bike.
    I'm thinking like Scott, either no plug or a bad O2 sensor.

    The coding plug is located normally in the white socket in the photo below.


  12. #12
    WineGuyD wineguyd's Avatar
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    Quote Originally Posted by Roger 04 RT View Post
    I'm thinking like Scott, either no plug or a bad O2 sensor.

    The coding plug is located normally in the white socket in the photo below.

    Rad, MarkM, Roger...thank you so much for the valuable info. I used to tinker many years ago on my bikes but right now this is an issue I'm going to have BMW fix...whether for free(for overlooking it in the tuneup) or paid. The bike is covered right now due to rain but tomorrow morning I'll check to see if a code plug is present. If missing, are these plug and play if I order one? Are they expensive?
    Purveyor of fine wines & spirits
    Rides a 1996 R1100R

  13. #13
    Registered User
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    Quote Originally Posted by wineguyd View Post
    Rad, MarkM, Roger...thank you so much for the valuable info. I used to tinker many years ago on my bikes but right now this is an issue I'm going to have BMW fix...whether for free(for overlooking it in the tuneup) or paid. The bike is covered right now due to rain but tomorrow morning I'll check to see if a code plug is present. If missing, are these plug and play if I order one? Are they expensive?
    You need a yellow one - something like $6 at beemer boneyard, translates to what, $65 at the dealer?
    It will only plug in one way.
    Even at $6 I would discourage you from peeking inside it. It is just a jumper.

    I doubt they gave the plug a thought doing a tune-up.

  14. #14
    Registered User dieselyoda's Avatar
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    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case)
    1986 K75S(the beutch), 1993 K1100RS (blown engine), 1997 Chev Short Box (4x4 with an LT1)
    "Life isn't about how fast or how high, it's about how well you bounce."

  15. #15
    Registered User
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    Bad odometer??
    Fuel leak?

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