Fuel Injection Systems

Discussion in 'Motorbike Technical Discussion' started by JC, Jul 12, 2005.

  1. JC

    JC Guest

    Can anyone describe how the fueling is controlled on a CBR1000RR Fireblade?

    My bike (Completely standard including exhaust) is emitting a puff of smoke
    when I accelerate away from junctions with a bit of enthusiasm. A bit more
    throttle than normal and half revs make it happen every time. Tootle of and
    it may or may not happen. According to the mechanic at the Honda dealership
    it's a fueling issue and nothing to worry about. Its only a bit of soot in
    their opinion.

    Going back to the time I had carbureted bikes it was usually recommended to
    change the jetting (Dynojet) if the exhaust was changed. When I got my first
    fuel injected Blade (RRY) it was said that they "tuned" themselves to the
    new pipe. I'm assuming all fuel injected bikes are the same and wondering
    how this works? Does the Lamba sensor in the exhaust constantly monitor the
    emissions and adjust accordingly via the ECU and fuel injectors or is there
    some other method? The dealer says the fueling on new Blades is particularly
    poor and suggested fitting a Power Commander may help (No guarantee though)
    However the more I think about this the sorer my head gets. If the PC for
    arguments sake leans the mixture of then surely the bikes original control
    system will richen the mix back again to compensate?

    A basic description of how fuel injection systems work is what I'm after
    then, unless of course you happen to know exactly how the 1000RR system
    works :eek:)

    TIA . John
    JC, Jul 12, 2005
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  2. JC

    Charlie Guest

    this is just a brief description of a 'basic' system, which I imagine is
    all bikes would use these days.

    air flow is measured at the intake, adequate fuel is injected. You make
    the engine breathe better, measured airflow is higher, more fuel is
    injected. lambda sensors are pretty useless things generally, and only
    do much at steady state throttle cruising conditions, or idle in some

    Don't know what your dealer is like but he could be spinning you a line
    to avoid pulling the engine apart.

    Charlie, Jul 15, 2005
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  3. You must have heard about the dangers of assuming anything. You just
    make an "ass" out of "u" and "ming"...

    And, I wouldn't completely trust any $tealer$hip mechanic who tells me
    I need to spend $300+ on aftermarket parts to make my original
    equipment FI system run right. It's supposed to run right, not puff out
    soot. It's entirely possible that what you have is a carboned up fuel
    injector and running a can of fuel injector cleaner through your gas
    tank (only use 3 ounces per tank full!) might just clean up your
    injectors and the soot blowing might stop!
    The "Lamba" sensor you describe is probably just a "hot oxygen sensor",
    sometimes called HO2S...

    Here's a description of how that gizmo works as related to a Ford

    When you first start an engine equipped with an oxygen sensor, the
    water temperature is low, and the O2 sensor's input
    isn't occuring yet. Your throttle position system is open. The mass
    flow sensor, whether it's a moving vane, or a heated wire indicates
    that there isn't much air flowing through the system. The ECU counts
    the number of ignition pulses from the signal generator and it can tell
    which cylinder needs a shot of fuel from the cam position sensor or a
    crank angle sensor, The ECU tells the FI system to run "open loop" or
    idle full rich....

    When you open the throttle for power the ECU logic ignores the O2
    sensor's input as air flow through the mass flow sensor increases. The
    ECU takes note of the engine RPM and the fact that the throttle
    position switch is closed. It runs is power full rich mode, holding the
    injector solenoids open longer...

    When your engine is idling or coasting the ECU logic compares the
    engine coolant temperature, throttle position and mass flow and RPM
    and reduces the fuel injection time and the engine runs in idle lean
    There are more than one model of Power Commander. Some motorbikes have
    a full range of sensors to send inputs to the ECU and the Power
    Commander will "trick" the ECU by modifying those inputs. Other
    motorbikes don't have the full range of sensors and the Power Commander
    takes direct control of the fuel injection process.

    I see from the Dennis Kirk catlog that a 2004 Honda CBR-1000RR uses a
    Power Commander III, and it's possible that that machine doesn't have
    all the sensors. You could research a bit by looking at the Electrical
    and other parts fiches on www.partsfish.com to see if you can gain some
    intelligence regarding just what sensors your machine has. They may
    have other names, or worse,just unintelligible part numbers.

    You could also read up on Power Commanders at www.powercommander.com to
    see if you can piece anything else together. But Dynojet is in the
    business of selling parts that are designed on the basis of proprietary
    information gained during their dynomometer tests and they just aren't
    going to tell you *everything* they know, you might just start up your
    own competing business!
    If the PC III takes direct control of your FI system, this shouldn't be
    a problem...
    krusty kritter, Jul 15, 2005
  4. JC

    JC Guest

    "krusty kritter" wrote in message
    Thanks for the reply krusty. You may well be right about a carboned up
    injector but I doubt it for the following reason (Maybe its a duff one?) My
    bike is 6 weeks old and has only covered 650 miles though I've been aware of
    the problem since the 300 mile mark. I'm currently working between my
    dealer, another dealer for a 2nd opinion (Next week) and Honda UK. Its the
    original dealers assessment that its soot (Black smoke) from fueling, my
    first thoughts were it was oil burning (I thought I could smell oil when
    following the bike and that the smoke was blue, I could be wrong however)
    which could be a much more serious problem. Time will tell.
    From PC website there are only 5 loop through sets of plugs. One for each
    injector and one for the TPS (throttle position sensor). The bike has 2 sets
    of injectors, upper set and a lower set with the PC loop throughs on the
    lowers. I haven't tried to figure out how many sensors there are yet.
    That'll make some good reading later on :eek:)

    JC, Jul 15, 2005
  5. JC

    JC Guest

    "Charlie" wrote in message
    See my reply to krusty Charlie. I think you may well be right about the
    dealer but if its fueling its got to be reasonably easy to fix. If its oil
    burning I don't want my dealer trying to fix it as I'd be looking for a
    different solution!!!

    JC, Jul 15, 2005
  6. I'm sure that your local Honda $tealer$hip will also tell you to wait
    and see what happens. They want problems to just "go away" and they
    want complaining customers to just go away, too...

    It could be possible that one fuel injector pintle doesn't seat and cut
    off the fuel cleanly. Which injector, though? What do the spark plugs
    look like, can you see that one plug is dirty and the others are clean?

    It could also be possible that your piston rings aren't completely
    seated, but the break-in process takes a lot less time with modern
    motorbikes than it used to. Engines with nikasil liners and cast-iron
    rings will break in in the first half hour, at least as far as rings
    are concerned.

    If an engine is running lean enough at higher RPM, it would burn any
    excess oil that gets past the rings. Maybe you would see evidence of
    oil burning on the round metal end of one spark plug, or on the ground
    electrode where it's welded to the plug body. Burned on oil would look
    black or brown and shiny and you could have a slight oil burning
    problem without actually oil-fouling the spark plug...

    An engine doesn't know what it's burning. Everything is fuel to an IC
    engine, gasoline, oil, the aluminum pistons and the steel valves, it
    will burn all of those things if the combustion temperature gets hot
    enough, but if the combustion temperature is too low, you get smoke out
    the exhaust pipe...

    Too much fuel or too much oil makes the combustion temperature too

    If I go out on a long putt on my bone stock FZR-1000 on slow roads
    where I can't use much throttle, it can't completely burn the mixture
    it's getting at part throttle, and the rings don't seal as well either
    at part throttle either...

    I will notice a lot of carbon come flying out the exhaust pipe when I
    finally get a chance to wind out first and second gears getting onto
    the freeway that takes me home. And the engine uses about half a quart
    of oil every 1000 miles...

    Part of the reason for this is that the rings are thin low-tension
    rings that are designed for high RPM operation. They just don't seal
    very well if the engine isn't wound up...

    And this might explain your soot blowing. But don't tell that to the
    guys at the
    $tealer$hip. They will just use that information to blow off other
    They'll say, "Wait a few thousand miles until your rings are fully

    Well, my FZR-1000 has about 30K miles on it, I would think that the
    rings would be seated by now, wouldn't you?

    But, certain unexpected quirky operating characteristics may be the
    price we have to pay for riding cutting edge technology motorbikes...
    krusty kritter, Jul 15, 2005
  7. JC

    JC Guest

    "krusty kritter" wrote in message

    *emails received*
    Heh, tell me about it.
    I haven't bothered to pull the plugs out as its a new bike and the dealer
    ought to be sorting it. I'll update when I have something to report.

    JC, Jul 15, 2005
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