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Thread: AFV at 128% & engine cuts

  1. #1
    Member herwawan's Avatar
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    AFV at 128% & engine cuts

    Hi peeps!

    After a ride today, it turns out my XB12 still needs some work. A bit of context here.

    The situation

    - When I bought it (less than a hundred miles ago), the engine won't feel so great and going over 4000 rpm would result in engine cuts, plus I'd hear a lot of after fire in the exhaust when the throttle would be released. Right before I bought the bike, the previous owner changed coil, wires and plugs. Didn't change much, I believe.

    - The bike went through the full 25,000 maintenance, with new oil + filter, spark plugs and so on, plus a new O2 sensor and battery (Deka 220CCA). Right after, I started driving it more and it felt much, much better: the after fire almost stopped and most of the time no more cuts after 4000 rpm.

    - Tonight I went for a ride, and once the bike was warm (with the fan going full speed), I experienced again the engine cuts after 4000 rpm and pretty intense after fire (at this point, not sure if it's back or after because of highway + earplugs, plus the very uncomfortable experience of the bike refusing to accelerate).

    When I got my bike back from Bartels' in LA few weeks ago (for changing my fan and my fork seal), Mitsu told me the engine cuts could very likely be because of the K&N filter and Jardine exhaust, which require a more suited ECM map. I did get the specific map from Buelltooth, but they recommend checking the AFV level beforehand.

    Therefore I plugged the Buelltooth to the bike tonight to check the AFV level, and it shows 128%.

    Screenshot_20180325-202700.jpg

    The brainstorming

    At this point, I would need some more help figure out in which direction I should keep digging. I did some research on the forum to get a bit more educated on the behavior of the ECM, the O2 sensor, the EGO and the AFV here. With this, I think I understand that:

    - The ECM could be "responding" to the K&N/Jardine requirement with a richer set up to compensate for the bigger volume of air coming in and out. Thus, the higher AFV. But then, my brain gets limited and I am unsure of what a "specific" map would change, if the AFV can already increase the value of the entire map by already 128%?

    - Am I misled by focusing only on the setup of the ECM? On Buelltooth "How-to", they indicate this could show an intake leak or faulty sensor. I just put a brand new O2 sensor, which leaves the intake leak open. I found the very interesting article from twin motorcycle in NL on the topic, their testing methods plus their new parts that seem to be less prone to leak. But I feel like I should close one topic before opening another one.

    It would be great to read your thought about this!

    Thanks

    Max.
    Last edited by herwawan; 03-26-2018 at 04:28 AM.

  2. #2
    Senior Member Cooter's Avatar
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    The K&N and Jardine will make a stock tune run a little lean. Decel popping and such. You are past that.

    With an AFV of 128% (adding 28% of fuel globally) I would think theres an intake leak of some kind. With the bike idling, pin point spray the intake gaskets and see if the idle changes.

  3. #3
    Member herwawan's Avatar
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    Quote Originally Posted by Cooter View Post
    The K&N and Jardine will make a stock tune run a little lean. Decel popping and such. You are past that.

    With an AFV of 128% (adding 28% of fuel globally) I would think theres an intake leak of some kind. With the bike idling, pin point spray the intake gaskets and see if the idle changes.
    Alright, good to exclude the ECM, I can focus on the potential intake leak. As for the spray, does it have to be necessary brake cleaner? I'm just curious about what's in it that creates the RPM to drop.

    EDIT: to try to clarify my mind - so far I believed that inflammable liquids would higher the RPM while for example penetrating oils would do the way around. So yeah, curious to learn something here!
    Last edited by herwawan; 03-26-2018 at 05:57 PM.

  4. #4
    Member herwawan's Avatar
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    Alrighty, test done tonight after a quick 10-minute ride in the neighborhood and few dogs scared by the decel popping.

    I did the test only from the right side (as described in the Manual). It's not an easy diagnostic. The manual mentions a "change of tone" and the video from Twin said it could literally stop an engine in a very bad case. In mine, I didn't stop (I didn't emptied the bottle tho haha) but I can "ear" a variation of the idle. It's not dramatic though, but it doesn't look like what I should expect it anyways, except if my case was really terrible.

    I guess it's still a lead and I should check the kit from Twin

  5. #5
    Senior Member lowkey's Avatar
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    herwawan, before you go tearing into the bike lets see if we can get your bike properly set up with the tools you have available. Please report back with this needed info: Year/model, ECMID (located on the main ECMDroid screen when connected to the bike), mileage and all known new items/sensors.

    1.) Now going off of your ECMdroid screen grab you TPS degrees states 3.4 which looks off at first glance, connect again to the bike and report back the degrees throttle closed and full open (should be 85 degrees).

    2.) If you want to quickly remedy the deceleration popping go into "ECM Parameters" / "General Config" / put a check next to "Deceleration Fuel Cut", then back out and "burn" to ECM.

    3.) AFV being that off indicates ECM-to-sensor mismatch or actual part problem (intake seals possibly?) To rule out ECM-to-sensor mismatch, you will need to do a proper TPS reset. If 03-07 bike you will take the air box apart down to the point where you can look down the velocity stack at the throttle body butterfly. Now you will back of the idle adjustment screw located just behind the left air scoop between it and the front cylinder. Back it out until snapping the throttle grip has the butterfly fully closed then back it out 1-2 full more turns. Connect the bike through ECMDroid and reset the TPS at this point (should read 0 degrees), thread the idle adjustment back in while connected until you see TPS degrees between 5.2 - 6.2. Bring the bike up to temperature (CLT above 160) and fine tune the idle adjustment screw once more to bring idle RPM to 1000. You have now set it properly but still need to report back what the degree value is for further evaluation.
    Do you experience rev hang (RPM's stick higher than idle RPM with clutch pulled in)? Either TPS value off or more air ingested than butterfly allowing for (intake leak). Going back to #1 if the TPS is found to be off and fixed at this point you will reset the AFV to 100%, ride for 30 min or more hitting open loop area of the map and report back with the new AFV value.

    4.) As for fuel cut at 4K, You will want to have your android device visible while riding and have "live data" ON report CLT value when you get the fuel cut, Also you can log the data and check the box for convert to MSL file. Provide the log here and I will have a look at it for you (also need ECMID for this or better yet the EEPROM.xpr).
    Last edited by lowkey; 03-27-2018 at 10:01 PM.

  6. #6
    Member herwawan's Avatar
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    lowkey, thank you for taking the time to prepare such a comprehensive reply! I will work on this probably over the weekend. In the meantime, here is the information you requested:

    - 2005 Buell XB12Scg (the chassis says 2004, but I guess the Scg only started officially on the market in 2005)
    - ECMID: BUEIB
    - 25,000 miles

    New items since I got it:

    Engine related:
    - Oil (20W50) + filter
    - Spark plugs (10R12X - I know, not the best but I read the NGK recommendation from Lunatic on a random topic a bit too late)
    - Fan (OEM Spal)
    - Clutch cover gasket
    - Battery (Deka ETX14)
    - O2 sensor (OEM)

    Chassis related:
    - Front isolator
    - Turn signal flasher
    - Fork seal

    As for the previous owner, I have the following information:

    - K&N filter installed in 2013
    - Jardine exhaust installed in 2013
    - Ignition coil & wires installed in 2018 (used, a few weeks before I bought it)

    Quick question regarding the "Deceleration Fuel Cut" option - why is this option not activated by default? I believe these engines are not very thirsty anyways, but I am wondering the advantage of keeping it on by default.

    As for the Rev Hang, I dit not notice it! And in the street of LA, I'm holding the clutch a LOT.

    For all the rest, I will be over the weekend!

  7. #7
    Senior Member lowkey's Avatar
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    No worries, decel fuel cut is an option through software that can pull the fuel value to ∅ under deceleration which normally has a value to feed a small amount of fuel within the fuel maps. This option brings the revs down quicker than normal but will not cause an issue, the side benefit is no decel popping. Refer back to my post and i will further evaluate the issue from the values you see.

    EDIT:

    herwawan, also while you have the air box removed, take the lower air box plate off and check that the 2 TPS sensor bolts are tight. There is a small amount of play in the holes in the TPS that the bolts secure through, if you can turn the TPS clockwise or counter clockwise you can never get the TPS signal to stabilize from resetting it. Take this time to turn and hold the TPS rotated clockwise while you snug down the 2 bolts before going though the reset procedure I posted earlier, this will have the TPS internal actuator tensioned to stabilize it's voltage while the throttle is fully closed (a trick used when sensor signal value jumps around at idle adjust screw stop/butterfly limiter).
    Last edited by lowkey; 03-29-2018 at 04:24 PM. Reason: more info

  8. #8
    Member herwawan's Avatar
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    lowkey, I just went through all this - although I just see the EDIT you made haha... Well if anything I'll just update the procedure later with this extra step!

    Here is the detail of all requested information / actions

    1) My TPS degree before the reset was showing 3.7
    2) I did not activate the feature yet for the sake of the testing, I'll use it in last resort once we're sure of everything
    3) It took me 5 minutes to find the screw... The cable was hanging down by itself, tied to nothing. It was hidden behind the air scoop, poor thing. I don't have a cable tie right now (crazy all the stuff we can have except the very thing we need) so I worked something out to fix it with the bunch of cable above - giving it the emplacement it should have.

    IMG_8121.jpg

    Anyways, I unscrewed the thing, went through all required steps and reset the TPS. Then I set the TPS degree at 5.5, then adjusted the idle around 1100 as suggested in the user manual once the CLT went over 160. My fine tune brought the TPS degree to 5.1, but it eventually displayed 4.8 and turned out to be better at this point. The idle was stable, all good.

    Then, I set the AFV to 100 (from 127.8 originally), and started the bike. The idle wasn't good at all (falling to eventually stop the engine). I went for a 30 min ride (and saved the log so you can check it out). After 10 minutes, the idle went back to stable but it is slightly too high (more around 1200 than 1100).

    The other interesting thing is that after fires on the exhaust side are even more present than before, but also the engine cuts are more violent. The first one was a HUGE backfire in my face, I wish I had worn my earplugs because that thing was loud.

    Then you can check the log for more details (see below), but basically it hardly goes over 4,000, and at some point I have to gear up because it's just not possible to hold the charge (and I hurt for that poor thing).

    After 30 minutes, I brought the bike back and checked the AFV. It was at 116.6.

    Link to the MSL log: https://drive.google.com/file/d/1xaX...ew?usp=sharing
    Link to the BIN log: https://drive.google.com/file/d/1-fI...ew?usp=sharing

    Last, but not least, I still feel like the bike is smelling pretty strong, not like gas station smell, but more like pretty strong "old car" smell. Don't know if this is something we want to put in the "symptom" column or not.

    That's it for me folks!
    Last edited by herwawan; 03-31-2018 at 08:17 PM.

  9. #9
    Senior Member lowkey's Avatar
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    I'll have a look at the log file as soon as i can but answer these 2 questions for me.

    1.) Does the “backfire“ come through the intake? Or only exhaust? Are you sure revs aren't slow to fall? Are you reading idle off the dash or the app? Set it for 1000RPM at 160clt.

    2.) When you have live data on and you have a TPS degree reading of 4.8-5.5 throttle closed, do you see 85.0 with the grip WOT?

  10. #10
    Member herwawan's Avatar
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    Quote Originally Posted by lowkey View Post
    I'll have a look at the log file as soon as i can but answer these 2 questions for me.

    1.) Does the “backfire“ come through the intake? Or only exhaust? Are you sure revs aren't slow to fall? Are you reading idle off the dash or the app? Set it for 1000RPM at 160clt.

    2.) When you have live data on and you have a TPS degree reading of 4.8-5.5 throttle closed, do you see 85.0 with the grip WOT?

    1) The first time I tried to reach over 4k rpm, it was so loud and it felt clearly closer to my face - I would say it was on the intake side, not the exhaust (but that's really based on a perception). Plus, the exhaust's after fire definitely are numerous, not so loud and don't happen during acceleration, only deceleration - I think I can identify them pretty well now

    I am only reading the idle from the app - I totally disregarded the dash. You can see the data from the log, it's not so off though, barely 50 rpm.

    Can you please specify "are you sure revs aren't slow to fall'? I am not sure to understand.

    2) Yes, sorry I forgot to confirm: both before and after the TPS, the maximum value with the grip WOT is 85.



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