| Author |
Message |
    
Fast1075
| | Posted on Friday, September 25, 2009 - 07:13 pm: | 
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Before I start...I have searched through the archives until my eyeballs are shot.
I just bought a 2004 XB12s...low miles, in absolutely beautiful condition...my problem is that it has a very annoying surge in any gear at low rpm/part throttle.
I AM NOT talking about the really touchy throttle response..it has that too...but different animal..I am learning throttle control and THAT will be fine.
As stated above, I have looked for info about it...and there is plenty of info that it is very common, but not universal.
What I am looking for is a defined solution to smooth it out. Most of the info I have dug up is "it's normal, ride faster" or "it's normal, deal with it".
Any input? What would be nice would be to come up with solutions and set them up as a "sticky" so the info will be easy to find.
The bike has the latest flash and has had a TPS reset, the bike is absolutely stock, plugs are fine, yada, yada. |
Thegibbon
| | Posted on Friday, September 25, 2009 - 09:14 pm: |
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Same here with an 06 Ulysses, just started about a month ago - can't figure it out. |
Sparky
| | Posted on Friday, September 25, 2009 - 11:25 pm: |
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Low miles, how many? Do you know the bike's service history, and more specifically, what has been done to it in its past?
Can you hold it steady at any RPM (under 3 grand) in neutral or does it surge then too?
Low throttle fueling calibration is mostly governed by the O2 sensor in the closed loop mode. It's possible that there is an intermittent electrical condition between the O2 sensor and the ECM and this condition could be causing the surging you feel. So if it exhibits this symptom under load but not while in neutral, then there might be a wiring issue related to the O2 sensor. |
Fast1075
| | Posted on Saturday, September 26, 2009 - 07:39 pm: |
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With the engine at full operating temperature (after a 25 mile ride) In neutral when I hold the engine speed at around 2500 rpm, it displays the problem.
If it was a carburated motor, I would say it was too lean...the rpm doesn't fluctuate a whole lot, but you can hear and feel a miss that is erratic.
While riding, if you go to more than quarter throttle with load on the engine (what would be enough throttle for normal accelleration) the surge or miss is unobtrusive but evident. At half to full throttle (don't use that position a whole lot yet) it just hauls the mail...quickly.
I have at this point no experience with with the fuel and ignition controls what so ever beyond a broad abstract generalization.
I am the very definition of "old school" so the learning curve promises to be both challenging and interesting. |
Sparky
| | Posted on Monday, September 28, 2009 - 09:29 pm: |
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Glad you mentioned relating to a carbureted motor.
The fuel metering of a carburetor is entirely related to the physics of airflow through a venturi which creates a vacuum to pull fuel through different sized jets to produce the best calibrated air/fuel mixture for normal operation. Different systems in a carb provide the full spectrum for cold starting, idle, part throttle, acceleration and full throttle operation.
Generally the Buell's EFI provides the same end results through electronics not physics. Compared to a carb, the amount of fuel to be delivered at any specific throttle setting is determined by the throttle (butterfly) position and how quickly it is moved.
So if one were to, say, snap open the throttle from idle to mid-range rpms, the EFI would tell the fuel injectors to squirt more gas than if the throttle were just held at the same mid-range position. The electronics, in effect, can detect and deliver what a carb's accelerator pump does just by monitoring how fast the throttle position is opened.
The key component for Buell's EFI is the Throttle Position Sensor (TPS). This sensor tells the ECM precisely what angle the throttle is set to (compared to fully shut) so that the EFI's mapping can make its best guess as to how much fuel to be delivered at any specific instance in time. It is imperative that the TPS is properly zeroed (TPS reset procedure) and set to a point within calibrated limits. If the TPS is even slightly out of cal, the EFI may not deliver precisely the amount of fuel in any given microsecond than your throttle hand asks for. It's that critical.
The TPS is but one of the motor's sensors that the EFI needs to operate correctly. Other critical sensors are IAT (Intake Air Temperature), ET (Engine Temperature), O2 (Oxygen sensor), BAS (Bank Angle Sensor), battery voltage, front and rear fuel injectors, ignition coil, fuel pump, tach, and cam sync. The EFI constantly monitors each of these sensors and if it detects an anomaly with any of them, it produces an error code which can be read back.
So in order to troubleshoot a symptom like part throttle surging, one must 1) determine the mechanical soundness of the engine including compression, intake and exhaust system seals, and 2) analyze the EFI system completely to determine if any of the sensors are going out of limits.
It should probably be said that one should verify that item 1) is complete before tackling item 2). There are other physical things too that may need to be looked at, such as the condition of the air and fuel filters, spark plugs, the integrity of the electrical wire harness, the ECM itself (no cracks in the seals of its connectors). It's best to take your time and check out each one of these things until you find out what is amiss. |
Fast1075
| | Posted on Friday, October 02, 2009 - 02:28 pm: |
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I did a breather bypass, removed the frame snorkel, checked all the wiring, checked to make sure there are no vacuum leaks. Haven't ridden the bike yet.
I also ordered a ECM cable, and got a copy of ECM spy...won't get those till next week.Ordered an RRS... |
Likacomet
| | Posted on Sunday, October 04, 2009 - 07:22 pm: |
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I also suffer from a cruise surge. I have a bone stock '02 S3T with a techlusion EFI box installed. I have had all the obvious things checked by my dealer but still have the very gentle surge. Drives me buggy and believe me, I don't have far to drive.
I also feel that it is a lean surge but why I can't adjust it out is a puzzlement. I really love the bike but I am completely frustrated with the situation.
I will be watching your post to see if anyone has a suggestion.
I wonder if a better O2 sensor would give any better feedback for the EFI metering box to address the lean setting.
Good luck to both of us,
Doug |
Fast1075
| | Posted on Monday, October 05, 2009 - 06:26 am: |
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Went for a ride with the club yesterday...the breather bypass seems to have made a difference...it still surges, but not as bad as stock...it's still a work in progress. |
Sparky
| | Posted on Monday, October 05, 2009 - 03:41 pm: |
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Fast, if the breather bypass seems to have made a difference, that might be an indication that the IAT sensor, which sits in the floor pan inside the air filter between the two stock breather hoses, might be oily or dirty.
In theory an IAT sensor covered by dirt and/or oil might be insulated from the incoming air temperature enough to inaccurately report correct data to the ECM, resulting in driveability issues. So you could try [gently] cleaning the IAT sensor with some isopropyl alcohol and see if that helps somewhat with the surging. |
Xcephasx
| | Posted on Thursday, September 02, 2010 - 02:39 am: |
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So how did all of this work out? |
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Troubleshooting (Poor Starting/Running/Handling/Ride Issues) »
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2004 XB12s surging at part throttle.