Hesitation on throttle, and then worse

Discussion in 'GS Boxers' started by dylanewilliams, Oct 4, 2012.

  1. dylanewilliams

    dylanewilliams Adventurer

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    <!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:DoNotOptimizeForBrowser/> </w:WordDocument> </xml><![endif]--> My bike is having problems. I read through these and other forums, have tried a number of things to remedy my issue, but it just got much worse and I need to figure this issue out now. I ride this bike every single day, I need it to commute on the weekdays and keep me sane on the weekends.

    The bike is a ’96 BMW R1100GS. I have ridden this bike hard 2 up fully loaded on dirt roads through Central America, the bike has taken a lot of abuse, and I have made quite a few repairs. It has about 70K miles on it. One peculiarity, it has one single throttle cable even though I understand all 96 and newer bikes had the 3 throttle cables.

    The problem began as a slight hesitation while in a high gear at a high speed. The motor would hesitate just a bit, as if there had not been supplied enough fuel. I had other work I needed to do, so I did the following:

    Replaced alternator belt (I think I still had the original belt on the bike)
    Replaced oil pressure switch (It was leaking oil)
    Repaired muffler, which was rusted on and required lots of force to remove, which may have translated into the engine block (when I installed the Jesse Bags, a replacement mounting bolt broke the carbon fiber skin of my D&D muffler, which I repaired for a second time after the initial repair finally fell out)
    Changed tranny fluid
    Replaced spark plugs
    Adjusted valve clearance
    Synched throttle bodies-air screw had to be adjusted almost all the way closed, w/in ¼ turn to get the idle to 1200

    I went on a long ride that weekend, and experienced the hesitation more and more, at one point cutting off for about a full second or two. I thought it must be a fuel issue, so I’d start with the routine maintenance stuff:

    Replaced fuel filter
    Completely drained and cleaned tank
    Blew out the air intake and overflow hoses with compressed air

    I rode the bike about 100 miles that weekend. On the first 25 nothing went wrong, at both street and highway speeds, but after that the occasional hesitation returned. After one left hand turn the hesitation was enormous, the motor almost died. The next day I did the following, figuring (hoping) it was either the TPS or my fuel pump was dying:
    Adjusted TPS to .015V at closed (lowest reading possible was .011V) before adjusting throttle body throttle stop screw
    Adjusted TPS to .385V after adjusting throttle body throttle stop screw
    Synched throttle bodies


    I have driven it maybe 100-150 miles since then with no problem until tonight. I just drove home, when I started the bike the motor was cold and took a few cranks to get started, more than normal. Upon starting, it idled fine, but I noticed an occasional very light hesitation on the freeway, just as before. Upon coming to the first stoplight at the exit, the motor died and would not restart. As I tried to restart the motor, I heard a sound like burst of compressed air I hear when turning the engine with a spark plug out, but loud. I also heard a loud metallic grinding for a brief period. As I cranked, the battery charging light flickered, which it has never done before. Eventually I got the motor to start and it ran fine as long as I kept the throttle open (RPM>2000), which I did the rest of the way home.

    Upon returning home, the motor died at idle, and when I tried to restart it I heard a loud metallic grinding sound again on the first crank. The second attempt started it but it now idles rough at about 700 or 800 RPM, which it continues to do if I turn it off and on again.

    Any ideas help! My ideas were :
    A clogged breather line
    Clogged fuel filter
    Out of sync throttle bodies
    Out of position TPS
    Bad fuel pump
    Unfortunately, I think there is something I am missing

    The two threads I initially found to be most helpful were here, but I don’t know if they apply since the troubles last night.

    http://www.advrider.com/forums/showthread.php?t=785145&page=2

    [FONT=&quot]http://www.advrider.com/forums/showthread.php?t=573731[/FONT]
    #1
  2. pcwirepro

    pcwirepro Aspiring Adventurer

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    Do you get a Hissing sound when you open the fuel filler?
    Any chance the "loud metallic grinding" is unrelated to the hesitation and stalling? What spark plugs did you use and did you gap them to spec? It sounds like you had a slight hesitation BEFORE you did all the work and now you have more or worse symptoms. Is that right? The Big Brass Screws should be out more than 1/4 turn to get the 1200 RPM you're shooting for. Something is off there. What did you use to do the TB sync?
    #2
  3. dylanewilliams

    dylanewilliams Adventurer

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    I am certain I didn't reverse the fuel out and return lines to the tank, one of the lines is marked, and on top of that this morning I pulled off the fuel in line at the right TB and when I turned on the cutoff switch, I had a solid stream of fuel coming out.

    There is no hissing sound when I open the fuel filler, I am relatively certain the problem is not just that I have a clogged breather line if that's where you're going. When I blew it out the air flowed freely.

    It's possible the metallic grinding is unrelated to the stalling, however it is certainly tied to the bike dying, so that would mean the dying and rough idling are a new, separate problem from the hesitation

    I used the bosch plugs that the BMW dealer sold me for the bike, and did not gap them, I installed them as is

    That is correct nothing I have done has remedied the problem:cry, it was there before and got worse.

    I definitely agree something is wrong with the TB screw being in so far. I used a mercury manometer to sync the TB's, first equalling the levels by adjusting the throttle cables, then adjusting the air screws to get the proper idle while keeping the sync

    One thing I am uncertain of is when I removed the fuel pump plate from the tank I forgot to mark the relative orientation. I reinstalled it so that the fuel pump sits forward and horizontal once everything is put back together. I think it's OK because when I fill the tank up the RID reads full gas, although it reads empty at 5 gallons on a 7 gallon tank.
    #3
  4. boxermoose

    boxermoose Now fully goosed

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    Inspect the hall effect sensor wires - if they are cooked you may want to do a preventive repalcement - there are aftermarket plates much cheaper then OEM - although as I understand it if the sensor fails it's pretty much dead right there

    There used to be instructions in the HOW
    #4
  5. pcwirepro

    pcwirepro Aspiring Adventurer

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  6. Jim Moore

    Jim Moore Long timer

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    Three thoughts. First, I had a similar problem on my 97 RT. It turne dout to be a relay that had worked itself loose. After shotgunning about $500 worth of parts it was fixed by pressing my thumb on the relay to reseat it. Expensive lesson.

    Second thought. HES. If you haven't replaced it, it's time. You don't have a classic HES failure, but it's close enough.

    Third, your O2 sensor. I had a similar problem with my GS. IT was rleated to the O2 sensor. Pull the cat code plug in the fusebos and see if that fixes it. On your bike pulling the CCP disconnects the O2 sensor.

    Good luck.
    #6
  7. eric2

    eric2 ®egister this:

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    stick coil. you've replaced everything else
    #7
  8. pcwirepro

    pcwirepro Aspiring Adventurer

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    Hmmm. Does the '96 have stick coils? I'm liking the loss of spark idea though. Could explain the "burst of compressed air" the OP heard.
    #8
  9. def

    def Ginger th wonder dog

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    No sticks on oilheads, thank goodness. However, it might be wise to check coil impedance with a VOM to insure there is adequate voltage to the plugs. Also, check the plug wires. I don;t know if your vintage has carbon wires but, have a look in a dark place at night with the engine at idle. You'll see corona if wires are leaky. Did you replace any in-the-tank fuel lines? Those lines can crack with age and leave your high pressure side with low fuel pressure. The poor driveability is especddially noticeable at higher RPMs when fuel pressure and full flow is needed. Also, next time, don't buy the Bosch plugs. Too costly. Autolite 3923s are preferred by pre dual-spark boxer owners. They're about $2.00 each and allow the gap to be adjusted with the traditional over-the-end ground electrode. Also, the Autolites improve cold starts and have been known to reduce surging somewhat.
    #9
  10. def

    def Ginger th wonder dog

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    With all respect for your willingness to help, it is unwise to give advice if you are not familiar with the advice you are giving. Stick coils, or the coil-on-plug design did not appear until the dual spark engine came along.....waaaaay after the OPs bike was built.
    #10
  11. def

    def Ginger th wonder dog

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    The burst of air you hear and a grinding sound????....I would remove the OHV covers and inspect the cam chain rails. Rotate the engine slowly with the alternator drive pulley nut. You may have damaged there. Next, if the chain rails look OK, I would remove the starter and clean and lube the mechanicals at the nose of the starter.
    #11
  12. Mrmerlin

    Mrmerlin K1300S fast as shi..

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    After reading this there are probably a few things that need to be done

    Since the driveability issues has never been fixed the two parts you have not addressed are the HES,
    and the 02 sensor possibly damaged by the rusty pipe fitting episode.

    That said the whoosh of air may be a loose spark plug or possibly stripped out threads causing the plug to come loose.

    if not that then maybe the intake manifold has a leak and is letting intake air escape possibly in conjunction with the failing HES

    I would also give the fuse relay panel a good going through maybe replace a running relay.

    The grinding may be incidental to the running and the battery terminals may be loose,
    or the wires that go to the starter are loose or dirty,
    or a failing ignition push button.

    This is what i would do in order
    Remove starter and clean and install,
    clean battery terminals.
    Inspect the spark plugs for correct torque,
    and possibly replace them with the autolites
    Inspect the intake manifolds for leaks
    Install a new airfilter
    Replace the O2 sensor,
    Replace the HES
    #12
  13. dylanewilliams

    dylanewilliams Adventurer

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    I am working on the bike now, and have checked the following things:

    I felt around the fusebox for loose relays, they all felt OK, but I pushed them all in to ensure they are seated. Per Jim Moore, I'd like to pull the Cat Code Plug, but don't know where it is.

    The resistance between the pins at the coil is .2 Ohms at the input, and 7.25 K Ohms between the post for the spark plug wires. The HES document linked to below says that second reading should be 13K Ohms, almost double what I have. The resistance of the spark plug wires on both sides is 6.2 K Ohms, although I'm not sure what they're supposed to be or if that gives new information.

    The battery looks fine, it's giving 12.87V

    The spark plugs are both carbon fouled. I've never had plugs look like that before on this bike.

    I Without yet removing the alternator belt and pulley, just the cover, I don't see any obvious problems with the HES wire. I did notice that the side of the new belt showed stitching, as if it may have rubbed against the engine breather line, although now there is clearance and I don't know if the stitching always showed

    In terms of replacing the HES and/or HES wires, I found this

    http://advwisdom.hogranch.com/Wisdom/oilhead_hall_sensors.pdf

    Is this a good reference?

    Similarly for the O2 sensor, no wire damage is obvious

    Thank you all for all the help so far!
    #13
  14. dylanewilliams

    dylanewilliams Adventurer

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    I found out which is the cat code plug, (it's the pink relay on my bike), pulled it and started the bike. Immediately the bike wanted to run at 2-3K rpm, very roughly, and then died. I reinstalled the CCP and got the same result when starting it, high rough rpm then death.

    I took off the belt and pulley and think I found the culprit for the screeching, the spring steel tab which holds the HES wire at the rubber boot at the top of the engine case was broken and rattling around with the belt, so that narrows down the symptoms at least.
    #14
  15. jalapenopete

    jalapenopete Adventurer

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    I had a '98 GS that I rode the crap out of. The last couple of years it was fix this, fix that, what now? The last big trip was from my home in GA out to Yellowstone and back last summer. I had a $2K+ bill to get it ready. The bike was good throughout. But, I got back and said "y'know, it's time for a new bike". Bought a lightly used 2010 GS and I'm happy as a clam. The new bikes are stratospherically (not sure that's a word) better. Of course you'll have these guys telling you that an old GS can be fixed on the side of the road by whittling a wrench out of piece of wood and replacing the starter from a '65 VW parked conveniently nearby, shit like that, but I'm not a mechanic.
    Maybe you should just get a newer bike. I mean carburetors.... hello 21st century! A newer bike under warranty means BMW will pick you and the bike up, fix it, put you in a hotel, and the hassles are done.
    IMHO.
    #15
  16. dylanewilliams

    dylanewilliams Adventurer

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    I checked the hall sensor and it seems to work fine. I followed the instructions on the link I asked about earlier, and at both cold and hot temps inserting a knife in the sensor shut off the led, although I think I might have got it too hot, as the plastic on one of the sensors started to melt.

    I am now going back to focusing on fuel, checking and cleaning the injectors, and checking for leaks in the intake manifold.

    I also have half a mind on the coil, my manual says the secondary resistance should be 1300, the advrider guide says it should be 13K and I have 7.25 Ohms.

    One of the early services I did and didn't mention was cleaning and reoiling my K&N air filter. In a lot of other threads a new filter keeps coming up, so should I discard the K&N and get a new air filter?

    EDIT:

    I put the hall sensor back in, put everything back together, and tried starting the bike. it wouldn't run unless I kept the throttle fairly open, and died as soon as I let go. I pulled one of the fuel injectors, and the tip looked clean, but I'm going to Kragen and will buy a fuel injector cleaner and soak both overnight. I'll also buy something to test the pressure of the fuel pump.

    A separate but possibly related issue, the tube that connects to the tank filler nozzle, that's for letting air in to not create a vacuum in the tank, leaks fule. It's done it for a while, but I didn't pay it any mind. I broke my rear shock on a pothole in costa rica and the charcoal canister was destroyed, so I figured the leaking gas was the condenate from the tank condensing in the line and then dripping out instead of evaporating, as it would have in the emissions canister. Today, however, after I just tried cranking the motor, about five seconds after I gave up, a fair amount(maybe a few ounces) of gas shot out of the tube. I have no idea what that's about



    BTW, I would love to get a new bike. If this had happened six months ago I would have. Unfortunately, I just transitioned from working back to school, so that's not really feasible right now. If it comes down to it though, I probably will get a KLR650. I could probably get one for the price of this bike, and I saw a lot of guys in Central America with them. They seem like a good alternative to the GS for people on a student's budget.
    #16
  17. def

    def Ginger th wonder dog

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    The oilhead boxer has been fuel injected for years without much drama. Carburetors have all but disappeared on everything but weed eaters. Maybe the OP will eventually opt for a new bike but, I'll bet he'll want to get to the bottom of his driveability issues on his current bike until that time. Stratospherically better? I'm not so sure. Stratospherically different? Yes. Stratospherically expensive? Absolutely! As for BMW picking you up and wining and dining you if their motorcycle hiccups? Not on this planet.
    #17
  18. def

    def Ginger th wonder dog

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    Here's my BMW REPROM Coil specs for my 2001 GS. Yours should be similar. Primary= ~0.5 Ohms Secondary= ~7.5K Ohms (cold) Remember, the ignition is a wasted spark design. K&N filter? Remove it and run the engine without the filter to determine if you're starving the engine for air. This may be the reason for the black plugs. Also, I read a recent post where the rider discovered air intake tubes that were blocked. Check for unobstructed air flow from the air box to the throttle bodies.
    #18
  19. Mrmerlin

    Mrmerlin K1300S fast as shi..

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    make sure to swap out the O2 sensor just checking wires isnt enough
    #19
  20. Jim Moore

    Jim Moore Long timer

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    The 13K spec is wrong. it's 7K. You're good there.
    #20