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Al_lighton
| | Posted on Tuesday, June 20, 2006 - 10:01 pm: | 
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My post above had an error in it. I believe closed loop starts at approximately 1500 RPM, not 2500 RPM as stated. The AFV acquisition region is a subset of the closed loop operational domain that starts higher than 1500 RPM, likely somewhere between 2000 and 2500 RPM.
Tom (teeps) is going to run a test on his bike to check my theory. He'll disconnect his O2 sensor and run it in the same manner that is causing the surging. If the surging stops, then we know for sure it is a closed loop artifact. If it still surges, then we know it isn't directly related.
Al |
Destroy
| | Posted on Saturday, June 24, 2006 - 09:52 am: |
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Any reports on how the bike ran with the O2 disconnected? |
Teeps
| | Posted on Saturday, June 24, 2006 - 09:54 am: |
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opto Posted on Saturday, June 24, 2006
In: Who Wants a Map thread:
Teeps,
Have you disconnected your 02 sensor yet? You may be pleasantly surprised.}
Yes, I have and no I was not; but I'm trying it again today as I discovered a battery problem and didn't want that to be a factor.
}
(Message edited by teeps on June 24, 2006) |
Opto
| | Posted on Sunday, June 25, 2006 - 05:51 am: |
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Al,
I like your post above explaining about how the ecm works. I used to run 10 LED's measuring a 0V to 1V range from the stock narrowband 02 sensor. It was quite easy to see when the 02 sensor voltage was in constant fluctuation or steady in open loop. The quickest way to get out of closed loop was to open the throttle a reasonable amount. Even at idle I believed the ecm to be in closed loop after a certain engine temp was reached, which only took about 20 seconds on a warm day from a dead cold start. I can hear it as the bike changes from a steady cold idle to a rougher slightly lower idle, like someone hit a switch. It's subtle, but it's there if you listen. I also remember being in closed loop at 150 k's (90 mph) the LED's were still bouncing around, but I was using a steady throttle to stay at that speed and it wasn't uphill.
The most puzzling thing about the ecm to me is that its closed loop operation does not *seem* to be a true closed loop at all, or does not act like a closed loop system in the way that other EFI systems do. The reason I say this is that in the circumstance that the ecm does need to adjust the AFV (say because 1. the tps just got reset 2. the AFV just got reset 3. you just filled up with a different grade fuel to what you normally run 4. last time you were riding the AFV got set to a completely different set of ambient weather conditions than what you are riding in today or 5. you fitted a different pipe etc) it appears that NO fuelling adjustments are made even though the ecm is in "closed loop" UNTIL the ecm has gathered enough data AND the power is cycled on the ecm. So it's possible to ride some distance and the ecm in its "closed loop" does not compensate until you switch off and then start the next leg of the ride. Other EFI systems in closed loop adjust on the fly, i.e. immediate adjustment as you ride along. I say this from experience, when my bike is running on the edge of too lean and trying to adjust, there are no adjustments made while riding, it still runs on the edge of too lean - while in its "closed loop", there are no adjustments made until the next start-up. It really is an unusual system, a system that will not adjust itself at all until you restart the bike for the next ride. And then on the next ride, it will make no adjustments until the ride after that - this is how it appears to work to me. So it's always optimally set itself for your last ride instead of the present ride.
Teeps, the reason I said you may be pleasantly surprised if you disconnect your 02 sensor is because when I was running an alternate EFI on my XB12 04 model, if it threw a code for the 02 sensor (i.e. the CEL came on), and I switched the fuel over to the stock ecm on the fly, it ran in constant open loop and ran a bit richer overall (well mainly in the closed loop area that suddenly became open loop) and was very nice to ride.
The Buell ecm has just as much character as the bike it runs! Don't know if this is good or bad!?  |
Teeps
| | Posted on Sunday, June 25, 2006 - 10:37 am: |
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Due to weather conditions, I was not able to ride yesterday.
Perhaps today.
Opto,
I read most of your post regarding the Mega Squirt you assembled for your bike. I'd sooner learn to live with the drive condition than try that... It's WAY more work than I'm willing or qualified to do.
Other than setting a DTC or the Engine light staying on; is there a down side to "just leaving the 02 sensor" disconnected?
Do you have an opinion on the Techlusion TFI system?
Update
25Jun06 -Sunday- 1:15PM
With the battey problem resolved I rode the Uyl 130 miles this morning.
At around 105 miles I stopped and disconnected the 02 sensor. Then finished the ride with it disconnected. Mostly 25/30 mph speed, road: flat, rolling, uphill and downhill. It didn't seem to matter, the surging/bucking/jerking was still there.
Someone mentioned timing might be a contribueting factor. This week I'll check the timing. And maybe try retarding it a few degs.}
(Message edited by teeps on June 25, 2006) |
Opto
| | Posted on Monday, June 26, 2006 - 02:46 am: |
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I've never used a TFI so have no opinion, sorry. Good idea to check the timing is correct. I'm disappointed that disconnecting the 02 sensor didn't help, that makes the problem more interesting. How many miles on your bike? and have you had the usual tps reset and AFV reset? Sorry if you've already answered these questions somewhere. I've never heard of so many stock bikes performing poorly, don't know what's going on. When you say lean surge between 1k and 2.5k rpm, I find it difficult to ride my bike smoothly at 2k rpm on a slight downhill, they're really not much good under 2.5k rpm, in the city traffic I ride at around 2.7k/2.8k rpm minimum, and slip the clutch or drop down a gear if I need to. Food for thought.
My Uly was running below average but picked up into "normal Buell mode" after a few thousand miles, meaning it's running well, no surges etc, so I'm pretty happy with that, especially after what I went through with the 04 XB12S which ran well on the stock ecm with Drummer, but surged in the low 3k rpm's and pinged with the race ecm. |
Teeps
| | Posted on Monday, June 26, 2006 - 11:06 am: |
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Opto,
My bike as 1700 miles.
I have done the TPS and AVF reset to both the stock ECM and the '05 ECM I got from Al. No change in driveability.
I'm beginning to think that this is just the nature of the beast. I called Dobek and,spoke to George, when I explained my complaint. He commented that he didn't know of any Buell that ran down that low (rpm.)
When I questioned him further, all he could say was the TFI will add more fuel. And, if I bought the TFI from them (Dobek) I could return it in 30 days if not satisfied. (could not get it in writing,though.)
The surge/buck/jerk seems worse when tach needle is about 1 to 2 needle widths below 2k or above, when trying to hold a steady speed. Accelerating off idle through that range is fine.
Timing check (possible retard) is next. |
Teeps
| | Posted on Monday, June 26, 2006 - 08:05 pm: |
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In the UPDATE POST above:
I forgot to indicate which gears I was trying to drive 25 to 30 mph at with the 02 sensor disconnected.
2nd and 3rd gears.
Also, when accelerating through the 1500 to 2500 rpm range the engine does not surge/buck or jerk.
This only happens when trying to hold a steady speed. |
Opto
| | Posted on Tuesday, June 27, 2006 - 06:01 am: |
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Yeah, I think you just need to keep it over 2700/2800 minimum at steady speed. These motors like to spin. Nothing wrong with sitting at 4000 rpm all day on the highway, whether it be 4th or 5th gear My missus rides my XB12S a fair bit, she was given instructions "do not ride below 3000rpm". As you get more miles up it will run better too. |
Fastfxrs
| | Posted on Tuesday, June 27, 2006 - 08:10 am: |
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I don't know how anyone can ride these things below 2ooo RPM. On a big twin H-D motor, this would be a good recipe for lower end failure over time. I don't lug any of my motors. I don't mind shifting.
Tim |
Teeps
| | Posted on Tuesday, June 27, 2006 - 09:38 am: |
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The riding conditions I'm specifying, the engine is hardly lugging at 2000rpm.
My expectation that a vehicle should operate smoothly at legal speeds is not unreasonable. It just might not be practicable. |
Thunderbox
| | Posted on Wednesday, June 28, 2006 - 09:19 am: |
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Teeps you are correct thinking the Uly can run smooth at 2000 rpm. Mine does and it has 0 mods. I have to ask this but have you checked your primary chain tension and did you have a TPS reset at the 1000 mile check. Is the timing right on? I also take it that this is with a warmed engine. Mine will buck a little if it is not warmed up. |
Teeps
| | Posted on Wednesday, June 28, 2006 - 10:58 am: |
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Thunderbox,
To your questions: Yes, yes, yes and yes...
I retarded the timing about 3degs, yesterday; didn't seem to make a difference. But I admit the test ride was short; about 3 miles.
I reserve the right to revise the above evaluation when I can ride the bike longer. |
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