TPS Alignment, Idle Speed Adjustment: Beyond Zero=Zero

Discussion in 'GS Boxers' started by roger 04 rt, Jul 25, 2014.

  1. roger 04 rt

    roger 04 rt Long timer

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    EDIT: PLEASE SEE THE LATER POST FOR UPDATED PROCEDURE, the early posts in this thread are for background only: https://advrider.com/f/threads/tps-...-beyond-zero-zero.996719/page-6#post-32357006


    Although I'm not a fan of adjusting the throttle stop screws or TPS, since they're factory calibrated (mine are untouched and are in spec). Many motorcycles have already been altered using the zero=zero procedure (and there may be wear beyond adjustable BBS limits) creating a need to restore either setting. What follows is a work in process based on what was learned in Trail'R's Thread on his R1150GS: GS-911 Error Code Question - Lambda Sensor Related . Comments and questions are welcomed.

    There are three conditions that need to be satisfied at Idle speed for the Motronic, TPS and throttle to be aligned:

    1. The TPS must be registered to the Motronic.
    2. The engine must be warm and functioning in Closed Loop (or on the R1100 European version without catalytic converter, set idle CO to 1.5% using the CO Pot).
    3. The Idle speed must be set to spec (e.g. 1100 RPM, +/- 50).

    I'm not going to provide all the details (e.g. explain how to work the throttle stop-nuts), just the essential steps for #1 and #3 above.

    1. TPS

    The correct method for setting the TPS does not involve a voltmeter since the purpose is to align (register) the TPS to the Motronic; therefore you need an output from the Motronic to know you've got it right. The TPS voltage is an interesting byproduct of the correct procedure.

    R1100
    The diagnostic connector has a TPS calibration pin. You can read about it in a few places:
    A) http://www.bmwmoa.org/forum/showthr...1150RT-surging&p=948289&viewfull=1#post948289
    B) http://www.largiader.com/articles/motronic.html
    C) http://www.k11og.org/forum/viewtopic.php?t=2110&postdays=0&postorder=asc&start=0

    R1150
    A GS-911 is easier to check that the TPS signal is within range but from measurements on my bike if the voltage at idle is 0.35 to 0.38, the Motronic can register it with the following procedure. The exact voltage does not matter.
    A) Remove Fuse 5 (or disconnect battery ground) for 5 minutes, then replace fuse.
    B) Key On
    C) Fully rotate throttle twice
    D) Key Off

    3. Idle Speed
    Refer to this thread for the reason why Idle Speed is important to the Motronic: (starting here, Idle Speed for Correct Mixture).

    The procedure below is so that TPS and idle speed don't interact. You may need a fan for cooling. Also it is important to have clean TBs and cable slack during adjustment. Cable slack re-adjusted per book when finished.

    A) Fully warm up the motorcycle and have a fan for cooling. Throttle bodies and BBS airways must be clean. Loosen left and right cable adjusters for 2 mm slack to insure throttles stay on stops.

    B) Remove the TPS but leave it plugged in to the harness. Set it to the idle position using the Motronic procedure outlined above in #1 (Diag Connector for R1100; TPS learn before removal, then GS-911 set to 0.32 degrees for R1150). (You could measure with DVM to learn thevoltage before removal and make sure it stayed set there.) By doing this, no matter what you do with the throttle stops, the Motronic will see IDLE input from the TPS and interaction is eliminated.

    C) Set the BBSs to 2.0 turns, whatever is considered the neutral position.

    D) Perform a TB sync & Idle Speed adjustment using the throttle stops and get as close as you can to idle spec. Then use BBS for final fine tuning. It is imperative that the idle speed is exactly the book value (1100 +/- 50 rpm for the R1150). Because the TPS is removed, it did not vary while you adjusted idle.

    E) Attach the TPS to the left TB and set per procedure outlined in point 2 above.

    When completed you will have the TPS registered, BBS at about 1.5 turns and the motor idling at spec (1100 RPM on an R1150).
    #1
  2. roger 04 rt

    roger 04 rt Long timer

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    Critique of Zero=Zero

    As I mentioned at the start of the thread, I'm not a fan of adjusting the TB Idle Stop screws but if you're considering zero=zero, or if someone has previously run zero=zero on your Oilhead, there are some issues with that procedure worth knowing. First, as I described at the start of this thread, the TPS may not be correctly registered to the Motronic because setting the TPS to a particular voltage does not have a specific meaning to the Motronic (it has a signal to tell you when the TPS is set correctly). Second, the throttle is left opened too far by the zero=zero procedure.

    Here are some facts about the TPS sensor from the Bosch data sheet.
    1) It has two precision potentiometers inside. One is for smaller throttle angles, the other used from mid-range through WOT. It is the same part on R1100 and R1150. Data sheet here: Throttle Position Sensor (Bosch 0 280 122 201).

    2) The finer range goes from zero to 23 degrees and varies by 187.5 mV per degree of rotation. That means each 20 mV is only 0.1 degrees. (An adjustment from 360 mV and 380 mV is almost too small for the Motronic to measure, and certainly has no effect.)

    3) The finer range has a divider ratio of 0.05:1 at zero degrees, which is about 250 mV.

    Point 3) has serious implications for the Lentini zero=zero procedure. It directs you to set the TPS to 10 mV at fully closed throttle. Based on the TPS spec, it should be set to 250 mV. Next zero=zero directs you to adjust the throttle stop screw until the TPS is 370 mV to 400mV. That means the throttle is opened 1.9 to 2.1 degrees as you adjust the throttle stop.

    If we assume that the Motronic is looking for approximately 350 mV (based on the GS-911 TPS checker) or 385 mV (based on zero=zero), or 360 mV by my calculation, and that the TPS spec is 250 mV for zero degrees rotation, then the Motronic is expecting that the throttle is only open 0.5 degrees to 0.7 degrees when the throttle is on the stop. (350-400 mV minus 250 mV at zero, divided by 187.5 mV per degree of rotation.) On the R1150, the GS-911 reads 0.32 degrees from the Motronic after TPS cal, that would suggest that my estimate of 0.5-0.7 degrees is too high but compared to the 2 degrees of throttle opening produced by the zero=zero procedure, it is at least closer.

    The only conclusion you can reach is that zero=zero opens the throttle about 1.5 degrees too far when on the stop, and that it is always open 1.5 degrees more than the Motronic measures. The consequences of this: the Motronic will output less fuel in the first few degrees, meaning it runs lean, a condition fixed later by mixture adaptation (consuming some of the adaptation range needlessly). Also, since the throttle has been opened too far by zero=zero, the BBS screws have to be closed down to compensate, which I believe is why some find that after using the zero=zero procedure, they cannot reduce their idle sufficiently.

    As I said at the outset of this thread, it is a work in process. I hope there is someone with an R1100 who will be able to make some measurements, feel free to PM me if you'd like to help.
    #2
  3. MassiveLee

    MassiveLee Banned

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    I am afraid that unless Bing rents a vacuum calibrating machine, people who rebuild their throttle bodies don't have much choice when comes to reindex the butterfly. The zero-zero method is perhaps the only solution that comes to my mind. Using a digital caliper to measure the depth from the TB opening to the butterfly is more inacurate as nothing proves th TB are exactly the same. and because the shafts are worn, taking measurements from a worn shaft won't help after reassembly.

    I set my TBs with zero-zero at 360mV, then set the TPS to 360mV uisng two tinsels an a voltmeter.

    Maybe somebody has the Bing specs about which vacuum values and under which pulling vacuum the TBs are set.
    #3
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  4. roger 04 rt

    roger 04 rt Long timer

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    MassiveLee, I'm working this with a guy now but zero=zero opens the butterflys too much allows too much air. The procedure I've outlined above will work better. However, if you want to work with zero=zero, at least start at 250 mV (not 10 mV) since that is what corresponds to zero degrees.
    #4
  5. MassiveLee

    MassiveLee Banned

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    Do you mean that the fully closed position shall be 250mV and not a nomonal 0v (actually, a few more millivolts not to freak out the multimeter). So, If I had set it at 0v and it is now at 360mV, do you mean I should set the TPS at 250mV + 360mV = 610mV

    You know, with the zero-zero method, the idle is perfectly set at 1100rpm wuith the bypass screws opened 540°.
    #5
  6. roger 04 rt

    roger 04 rt Long timer

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    If you process all the detail in the first two posts, but you still wanted to use the format of zero=zero, you would set it at 250 mV and open it 110 to 120 addition mV so that the final reading was 360-370 mV. That would open the throttle about 0.6-0.7 degrees. (I would be very interested to know how many turns out on the BBS were required.)

    The way you have it now, the Motronic thinks the throttle is open 1.5 degrees less than actual for all throttle angles. Obviously this only matters at small throttle angles--where these bikes tend to surge.

    Edit
    I went out and measured my BBS settings, stock TBs with blue paint, blue paint on the TPS. They are out 1 3/4 turns, but I'm running an AFR of 13.8:1 which means I need less air than stock. When I get a moment I will set my AFR to stock and see how much further out the BBSs end up.
    #6
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  7. roger 04 rt

    roger 04 rt Long timer

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    Comment on Earlier Posts
    In the earlier posts in this thread there are mistakes or omissions that I have found. The biggest error is the conventional understanding of what rotating the throttle does after a Motronic reset and recal. As I mentioned, this is a work-in-progress. I have a new recommendation for zero=250 later in the post.

    New Measurements
    I spent a few hours yesterday making measurement of the TPS and Motronic for small throttle angles and found quite a few interesting things. Among the things I learned (and although I can see vestiges of the factory paint), I see that someone performed zero=zero on my R1150 since there is no fully intact paint. The BBSs are about equal so I'm not too concerned but will go back and reset it at some point.

    To make the measurements, I attached a good DVM between pins 1 and 4 or the TPS and connected the GS-911 to the diagnostic port. This way I could measure the voltage change versus throttle angle change as reported by the Motronic. I was careful to move the TPS very slowly (by rotating it with the throttle lock on), and find the trip point for each reading of the GS-911. It outputs angles with a resolution of 0.32 degrees. So the angles it registers are: 0, 0.32, 0.64, 0.96, 1.28, 1.92, etc. I also monitored the Idle Switch Off indicator reported by the GS-911. Lastly, I measured (and then calculated to confirm) how much physical rotation of the TPS per 10 mV (it's tiny) of voltage change on pin 1 (the high resolution wiper).

    Here's what I've found:

    1) TPS cal (rotating the throttle) does not have any effect on the voltage-to-throttle angle as measured by the Motronic. This was a surprise because we all "believed" that TPS cal (rotate the throttle twice) learns the idle and full scale positions. I set the TPS as low as 300 mV and as high as 375 mV, performed a full reset (10 minutes) and recal. In spite of that, the point at which the Motronic/GS-911 transitioned from reporting 0.32 degrees to 0.64, 0.96 and the point at which the Idle Switch reported OFF were the same whether I set the TPS to 300, 350 or 375 mV.

    It now seems clear to me that the reason for setting the TPS is to position it to 0.48 degrees, which is always approximately 340 mV to 350 mV.

    2) The A/D converter in the Motronic is 8 bits (expected) and the step size for each "bit" of the A/D is approximately 20 mV. The Motronic reported step sizes are 0.32 degrees, which equals 60 mV, which means each bit of the A/D is about 0.11 degrees (20 mV). That means one degree is about 200 mV (187.5 to be exact). So the angle to voltage conversion measured (and then calculated by me) below. Because the A/D has some tiny fluctuations (noise) these values can change by 10-20 mV.

    0.00 degrees: 250 mV to 309 mV
    0.32 degrees: 310 mV to 369 mV
    0.64 degrees: 370 mV to 429 mV
    0.96 degrees: 430 mV to 490 mV

    Idle Switch Off: ~430 mV

    3) Using a feeler gauge under the throttle stop, I measured that every 0.1 degree of TPS rotation is about 0.0025" of movement at the TPS locking screw. This means a 10 mV change in DVM reading is the result of about 1-2 thousandths of an inch of movement!

    4) On my R1150 the A/D "noise" at small throttle angles seems very good, less than one bit. That means that sometimes the transition for, say, 0.96 degrees is at 410 mV and sometimes it is at 430 mV. 0.96 degrees is the point that the Motronic reports Idle Switch: OFF.

    5) If you want to readjust the TPS and throttle stops (because someone else changed them) zero=zero is the wrong procedure. It certainly leads to the throttle angle being opened too much (10 mV at zero degrees, then to 370 mV, which means the throttle is opened 1.92 degrees). Based on a 340 mV target for the TPS (confirmed with the GS-911 and equal to the mid-point of 0.32 degrees), the throttle is meant to be opened about 0.48 degrees and the rest of the air comes from the BBS. (I could be off a bit on the 1.92 degrees since there is no spec for angular rotation below 250 mV on the Bosch TPS.)

    Looking at the TPS data sheet, I have an explanation for why the requirement to rotate the throttle twice after a Motronic reset on the R1150 (the R1100 may be learning it on-the-fly, or BMW may have fixed a problem by introducing the procedure on the R1150), since it doesn't seem to calibrate the end point. There are two potentiometers in the TPS. The fine-tps (0-23 degrees throttle) has it's upper and lower points specified. TPS-coarse has only it's upper point spec'ed. That means that rotating the throttle allows the Motronic to measure and learn the crossover point and the start of tps-coarse. It may be doing this by using the fine-tps to measure the starting point of the coarse-tps, thereby having a seamless crossover between the two.

    Also, I now also can see why moving the TPS idle setting to 370-385 mV can affect engine operation, at least temporarily, especially on the no-cat configuration of the R1100. At that voltage, the Motronic is just starting to register 0.64 degrees, so the Motronic then goes up to the next 0.32 degrees more quickly. This would give a slight rich fueling bias for throttle angles below (I'm estimating) 5 degrees. I doubt that it is a permanent benefit but could be, very slightly around idle. (Going a little further with the reasoning, since zero=zero opens the throttle too much, it makes sense that a higher TPS voltage would get the TPS reading by the Motronic closer to the actual throttle-angle-plus-BBS air flow. On the Closed Loop Oilheads, Adaptation Values will fix this up, but as you know, adaptation is not perfect. Therefore, it is better to get it right from the start.)

    Recommendation
    The procedure I suggested earlier in the thread for restoring the throttle stops and TPS will work but now seems too complicated. I also realized you can set the TPS with voltage, something I didn't think was possible because of the conventional-wisdom of what rotating the throttle twice did after reset. I still believe that the GS-911 or LED (for R1100) is the preferred route for setting just the TPS because it is a Closed Loop process that includes the Motronic.

    Although I don't advocate changing the throttle stops or TPS, for someone (like me?) who has had their TPS Lentini-ized by zero=zero and wants to get it set correctly, a zero=250 procedure can be used.

    Begin by setting zero degrees throttle to 250 mV (instead of 10 mV recommended in zero=zero). Then the left throttle should be rotated to 340-350 mV, which will rotate the throttle open 0.48 degrees. Then just follow the rest of the Lentini procedure. That will undoubtedly require the BBSs to be opened more than two turns. I will experiment with this on my bike to see how many turns are required when I have time.

    Next Tests
    My next experiments will be to close the BBSs and see how much the throttle needs to be opened to idle at 1100 and at an AFR of 14.7 to 1. Then I will see how many turns the BBSs can be opened before the RPMs stop increasing.
    #7
  8. mouthfulloflake

    mouthfulloflake Not afraid

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    Very interesting stuff Roger.

    I wish I understood why I could never get the LED to light on mine, I wonder if my diagnostic plug has been cut or disabled since the ABS module was removed by what appears to have been a hatchet from a previous owner.
    #8
  9. roger 04 rt

    roger 04 rt Long timer

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    MOF, Did you connect the LED (with built in 12V resistor): Anode to +12V, Cathode to Pin 1 of the Diag connector. Then ground Pin 3, then turn on ignition?

    With the recent measurements above, I'm conclude that the MA 2.2 and MA 2.4 behave the same. Each has a nominal setting of 340-350 mV for center of the 0.32 degree range. Here are some measurements taken on an Australian R1100:

    "The idle LED is ON only between .327mV and .386mV as measured with my Fluke meter on my TPS."

    This is essentially the same range that I measured on an R1150 the other day.

    That means that the LED confirms that you are within the proper range. Note that it is almost exactly 60 mV wide, the width of 0.32 degrees.

    I can't think of a test to confirm that the function of TPS alignment on the R1150 is to align the two potentiometers inside the TPS module, but it is my best explanation, given that: a) TPS alignment doesn't affect the bottom of the range, and b) that the exact angle at WOT is not as critical.

    The R1100 (without the procedure to twist the throttle twice) either a) has no such alignment or b) does it automatically as and when the throttle moves through the crossover point. I don't think we'll ever know.
    #9
  10. mouthfulloflake

    mouthfulloflake Not afraid

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    I am 99% sure that I followed your instructions, and did use the led with built in resistor, I have slept since then though so not 100%
    Ill check again soon.

    I plan to follow those wires from the diagnostic plug to make sure they arent severed somewhere also, there is a bunch of stuff disconnected under the tank.
    #10
  11. roger 04 rt

    roger 04 rt Long timer

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    Some further observations:

    Zero=zero opens the throttle vane 1.92 degrees when the lefthand stop screw is adjusted from 10 mV to 250 mV, however, the Motronic only reads 0.32 or 0.64 degrees. Then if you open the throttle another 1.28 degrees, the throttle vane is actually open 2.20 degrees but the Motronic reads 1.6 degrees. In other words your Motronic is always reading incorrectly lean.

    Zero=250, as described above results in the actual throttle angle being the same as the measured angle as read by the Motronic, neither lean nor rich.
    #11
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  12. cruzer

    cruzer n00b

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    Roger,

    Thanks for that timely work. Wow, I was in the middle of Mr Lentini's zero - zero and couldn't get a reading so went I-exploring and your article came up, finished about 4 hours before

    The stop screws are bastards to get at.

    Pulled #5 to reset Motronic which is a 2.4. 2X's full throttle rotation. Set TPS @ 250...wound out to 350 with stop screw and cinched it all down.
    Then did right side. Idle is 1100 exactly. Smooth response with vibration gone and almost no surge. God..these thngs are fast.

    My son gave me this bike and it's "04 11SA. He bought the bike with 6K on it and a month later the engine blew. My brother rebuilt it with another low miles unit though a single spark.

    He had a devil of a time setting it up. He rebuilds things, I like the tuning part.

    It may not be quite perfect yet as I used a prosynch rather than mercury and even setting it on one cylinder with all tubes connected the readings were different.
    Wasn't really sure if the Motronic would pick up the 2 sparks to one without singing everything but it seems to have worked very well.

    This is my 5th Beemer and I always liked how smoothly they could be tuned. Could never get hold of it long enough to do anything. He's in Philly I'm in Canada

    I know how difficult it is for the manufacturers to please the environmentalists and "mums the word". Pollytiks. We seem to have to figure this stuff out now for ourselves.

    Without your and Rob Lentin's and others efforts I would have been lost... so let me buy you a round should we meet.

    Cheers,
    Jonathan
    #12
  13. roger 04 rt

    roger 04 rt Long timer

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    Glad to get your feedback. This is still a work in progress so it's important to hear how it goes.

    One question, how many turns out were your Idle Bypass (BBS) screws?
    #13
  14. cruzer

    cruzer n00b

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    2 and 2.

    Went for a couple of hours ride this am. on secondary roads and twisty local .

    It shifts much more smoothly. Mid range is very stable by comparison to
    how she ran before. Roll on and off as well. Vibration is much reduced.

    When I next visit my brother we"ll recheck with his mercury stix. Mine are iffy.

    We can only get 91 octane here and that does seem to make a difference. 94 is really only available in larger towns.

    As an aside I did put in Autolite double platinum 3923's gapped at .8mm.
    This too was a large improvement at the time...seemed quite miraculous.
    #14
  15. def

    def Ginger th wonder dog

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    Egaaads...double platinum? How much did those cost?

    I use the plain-jane 3923s at ~$2.00 each. My last pair lasted about 43,000 miles.
    #15
  16. cruzer

    cruzer n00b

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    Getting 46mpg over 514 miles all highway and back roads.
    On www.fuelly.com there are 19 r1100s's, all years. They run between 29-46 mpg. Highest fill up was 48.

    I also set the valves at 12 and 14 a la Lentinti ( super tuning) as opposed to 06 and 12.
    As it's not pinging, I may advance the timing too.

    Being at the top end of the mpg scale, I wonder if it's perhaps a wee bit lean? I get that one desires to be neither rich nor lean with throttlebody synch.

    Still have to perfectly synchronize as yet with mercury sticks.
    #16
  17. roger 04 rt

    roger 04 rt Long timer

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    Cruzer, your mileage looks normal to me.

    The mixture is controlled by your O2 sensor so there isn't much you can do with throttle body sync or TPS adjustment to affect mixture richness/leanness.

    If you want to richen the mixture, join the Wideband O2 thread in the Vendors section since It's not allowed to comment on that here.
    #17
  18. luca9277

    luca9277 Been here awhile

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    Hi Roger,
    I have read with great interest your posts, I hope I get get some feedback from either you or another knowledgable fellow ADV rider.
    I have a 2001 R1150GS (single spark) with about 150miles on it and fitted with:
    Leo Vince exhaust
    K&N Airfilter
    Iridium plugs
    BoosterPlus (AF-XIED on its way)
    Y-pipe (not Cat)
    No code plug
    Current mileage: 30-35 mpg

    The bike runs overall OK however it does surge a bit and this is why I fitted a BP in first place.
    The BP didnt help much so I got a AF-XIED but I haven't received it yet.

    My TB have been badly adjusted in the past as well as the TPS which was replaced not long ago.

    I have a Twin Max and a GS 911 I used to (trying) understand what is going on.
    When syncing the TB I notice that it was really hard to adjust idle, the right hand side BBS was about 2 turns out the left was nearly closed.

    Reading your post (and Lentini's instruction) I tried to restore the zero=zero working on the stop screws (focusing on the LH one first).

    Somehow I wasnt able to get a good reading on the DVM so I used the GS911 to adjust the zero, the challenge is that opening and closing the throttle I could get close to 0.32 Deg but at time the throttle would stop at 0Deg or 0.64Deg.
    It doesnt matter how hard I tried I always had a bit of fluctuation.

    I have done a bunch of adjustment and thought I got it right with idle at about 1100 +/-50 RPM with about 3 bard on the temp reader on the RID.
    (when cooler I need to use the fast idle switch and it lifts the RMPs just enough).

    Issue is I live in Singapore with a steady 90F all year round, I almost always ride with 5 or 6 bars on the temp display.

    As soon as the bike gets "hot"er the idle jumps to 1,500/1,700 RPMs.

    Both BBS are about half turn from close at the moment.

    Questions:

    When I plot the CO2 on the GS911 it always seem to go on the lean side, when I log data the lambda voltage swings widely.
    I plotted a few things.

    Does this chart reflect a "properly working bike" or are there signs of something odd?

    How can I adjust the idle so that I can keep the bike running with fast idle when cold and get to a 1100 RMP mark when hot?



    At the moment, after all these changes and a few resets of the motronic the surge seems fairly low, it is still there but not as bad as before.
    Once I get the AF-XIED I am also planning to put in a set of Autolite 3923 plugs
    Looking at the set up of my bike should I consider using a code plug?

    Below is the data I charted (some values are scaled to keep it readable.. The TPS is on the secondary axle (to the right).
    [​IMG]
    #18
  19. luca9277

    luca9277 Been here awhile

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    A slightly better reading legend..
    [​IMG]
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  20. roger 04 rt

    roger 04 rt Long timer

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    Hi Luca, Nice job with the data collection and plotting. The data doesn't look quite right to me at a quick glance. When the motor is warm and the throttle is closed, you should have a varying lambda sensor voltage, indicative of closed loop. In your case it looks like the O2 voltage goes low (lean) at idle.

    I've PM'd you so that you can send me the CSV file and I'll look at it in more detail.

    If you follow the Lentini procedure but start at 250 mV with the throttle plates closed, you should get an about equal BBS setting at idle.
    #20