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Old 06-30-2007, 07:38 PM   #16
Anorak
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Jim, using the rotational velocity to read mixture, is the crank speed change in the course of one revolution at set load being sensed?
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Old 06-30-2007, 08:37 PM   #17
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Quote:
Originally Posted by Fluorescentbrown
Jim, using the rotational velocity to read mixture, is the crank speed change in the course of one revolution at set load being sensed?
I don't know if I understand the question exactly, if I do, yes. At any given load, the crank velocity does change as the injector pusewith is adjusted above and below stoichiometric.

With or without an O2 sensor, the ECU does not operate in closed loop (i.e., adjust the mixture back and forth across stoichiometric) over the entire load map.

And as you can imagine, without an O2 sensor, the mixture isn't read directly. Instead, crossing the 'stoichiometric threshold' is inferred via crank velocity.

You prolly know how the ECU does that using an O2 sensor. It's done in about the same way using crank velocity.

The difference is, instead of the ECU adjusting the injector pulsewidth up or down for each combustion cycle while looking at the O2 sensor output, instead ECU looks at portions of the crank rotation time. One too many insteads there.

Adjusting the pulsewidth at any given load to find either combustion limit (maybe call it blocking) takes no more than a few dozen combustion cycles.

Say the ECU finds the 'low limit' of combustion by shortening the injector pulse until the percentage of irregular combustion events reaches 15%. That's three out of 20. Irregular doesn't mean combustion did not happen. It means that for 15% of combustion events, the crank speed between TDC and BDC is lower than the other 85%.

If I know you, I'm betting you can work it out from there


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Old 06-30-2007, 11:05 PM   #18
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Thanks Jim. You understood my question. As I was trying to phrase the question I was able to visualize the process so I started to understand it. Next question, how much resolution does the motronic on the 1150 have. Can it read less 360 degrees?
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Old 06-30-2007, 11:39 PM   #19
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Ahhhh the beginnings of another technical article with some gusto.
How does the moronic brain REALLY work
Inquiring minds need to know

Carry on

JJ
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Old 07-01-2007, 03:50 AM   #20
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Quote:
Originally Posted by Fluorescentbrown
Thanks Jim. Next question, how much resolution does the motronic on the 1150 have. Can it read less 360 degrees?
Sure thing. At a minimum, microsecond resolution. And yes, sub-degree resolution.


But adjusting the mixture using the crank velocity, like we're talking about, is usually a pure timing operation. Meaning that a conversion of time to degrees or rpm isn't usually done in order to do the task of sensing crank 'travel time'.

Here's some FYI . . The 2 Hall effect sensors give 4 measuring points, or marks say, around the 360 circle. 0 - 135 - 180 - 315 As you know, the crank pulley trips the Hall sensors. The pulley has a 45 'window' in it that passes over the Hall sensors. The 'window' is fixed to the crankshaft, and spans the distance between TDC and 45.

The 45 slices are a reasonably close guess using a degree wheel and a meter on the Hall sensor output. The mark locations are not related to the ultimate degree resolution capability of the processor. The additional marks are needed for other reasons, scheduling the ignition event for one.

The Motronic times out fuel injector pulses with 1s resolution, that's 1MHz. To calculate and time an event with microsecond resolution, while doing other tasks, requires the processor to operate at a much higher speed. I do not remember the speed of the crystal running the Siemens processor, if I remember it was 20 or 32MHz. That seems like a reasonable minimum speed to carry out ECU tasks with enough headroom to spare.

As the injector time is counted with 1s resolution, it's reasonable to consider that, at a minimum, 1us is also the resolution of the crank timing. Though it's easily possible that rather than time a complete 360 crank revolution, that instead the 0-135 slice is timed at a much higher rate. Perhaps at a resolution as much 16 times finer than 1s.

I realize I just said I'm guessing, but my guesses and min/max estimates are in the middle ground of usual practice.

Use the known injector timing resolution of 1s, and consider 1s to also be the resolution of the crank velocity timer. With microsecond resolution at the crank, at 7700rpm the crank rotates .0462 in 1s. So that's pretty good.


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Poolside screwed with this post 07-01-2007 at 11:58 AM
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Old 07-01-2007, 02:59 PM   #21
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So if I understand this correctly the moronic brain can compare crank rotation timing, twice per revolution, calculate accleration rates (or lack of same) and adjust the injector pulse width accordingly. All based on an ≈45 'window' that the hall effect sensor 'sees'. It also uses this data to calculate the 'oscillating' action of delivering 'extra' fuel to the cat to keep it functioning at its proper operating temperature.

This also helps to explain how the engine can/will still run with the cat converter dumbed down (using a substitute pot). AND helps with how the limp home mode can get the engine to run, at all.

HhhhMmmmm.

Now all we have to do is wait for some more schmart peoples questions/comments with the subsequent answers of enlightenment to shead yet further insight into the inner workings of, 'How Things Work' - EFI, what goes on behind closed doors.

JJ
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Old 07-01-2007, 03:10 PM   #22
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No O2

Hate to bring this up, but my 01 GS runs just fine sans O2 . It's been unplugged for about 10k miles. Runnng a Y pipe Remus. Without the cat a 02 isn't needed.
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Old 07-01-2007, 03:19 PM   #23
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So your saying I went through all that for no reason???

Dammmm....

Well for the record the o2 sensor I am now running is a Bosch # 13231,
it costs half of what the BMW dealer wanted.

I gotit at a local NAPA when the mc shop did not have one in stock, As I sadi earlier the mc shop wanted $ 186.00 at NAPA around $ 92.00.

Went for a 270 mile ride today and it runs great, i will say with the Y pipe there is some poping on deacceleration. Yes I used high temp RTV, it still pops.
The bike sounds a little more gutsy, only sounds I cant tell any performance difference from cat to Y pipe. What I did notice is that the temp runs one bar cooler then it did with the cat.
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Old 07-02-2007, 04:24 AM   #24
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You are ahead of the game compared to me, at least you are using what you bought. I paid full papa for a new OEM sensor when the bike was 1 year old, then I cut the signal lead lead and ran an extension wire out from under the tank so I could get to it for testing.

It's been disconnected like in the picture below for I don't know, two years now? The brown and gray wires are the O2 signal extension leads. You can see they're just hanging there. The sensor still works. They are pretty stout too, the signal lead can be shorted to ground indefinitely with no harm to the sensor.

You can rig something like this if you want, and experiment with twisting the leads together for a time, then disconnect them for a time. See which works better.




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Old 07-02-2007, 04:45 AM   #25
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Yea that's about it in a nutshell smart guy.

The 45 window can be used to measure a 135 sweep of the crank between 0 and 135 degrees. That's a good slice in the right place because it's most of the combustion stroke.

The trailing edge of the crank pulley window 'closes' on the top sensor at 0 crank angle, or TDC. Then the leading edge of the window 'opens' on the bottom sensor at 135 crank angle.

Quote:
Originally Posted by johnjen
So if I understand this correctly the moronic brain can compare crank rotation timing, twice per revolution, calculate accleration rates (or lack of same) and adjust the injector pulse width accordingly. All based on an ≈45 'window' that the hall effect sensor 'sees'. It also uses this data to calculate the 'oscillating' action of delivering 'extra' fuel to the cat to keep it functioning at its proper operating temperature.

This also helps to explain how the engine can/will still run with the cat converter dumbed down (using a substitute pot). AND helps with how the limp home mode can get the engine to run, at all.
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Old 06-16-2010, 06:39 PM   #26
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Could someone please let me know how to disconnect the 02 sensor on a 2009 1200GS? I have the sensor unscrewed I just can't figure out how to disconnect the wire at the closest harness. Thanks.
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Old 06-16-2010, 07:37 PM   #27
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Quote:
Originally Posted by sauce25
Could someone please let me know how to disconnect the 02 sensor on a 2009 1200GS? I have the sensor unscrewed I just can't figure out how to disconnect the wire at the closest harness. Thanks.
I stumbled around with this, eventually removing the plastic brackets from the bottom of the cylinder heads to figure it out. Then I realized that the connector assemblies just slip out of the brackets, allowing you to use a screwdriver to get under the tabs that hold the connectors together.

If this isn't clear -- and I'm certainly not describing it the best possible way -- just fiddle around with the connectors on the brackets until you figure it out.

...

I just went out to the bike and slipped the connector off the bottom of the right cylinder and slipped it back on. It's so easy this caveman can do it.
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Old 06-16-2010, 08:42 PM   #28
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Your description sounds somewhat like the big connector from the tank into the wiring harness on my 1150. The 2 halves clip together and the harness side connector clips onto a bracket that holds the whole thing in place.

Once you've done it once or twice it becomes obvious.

JJ

Quote:
Originally Posted by Geoffster
I stumbled around with this, eventually removing the plastic brackets from the bottom of the cylinder heads to figure it out. Then I realized that the connector assemblies just slip out of the brackets, allowing you to use a screwdriver to get under the tabs that hold the connectors together.

If this isn't clear -- and I'm certainly not describing it the best possible way -- just fiddle around with the connectors on the brackets until you figure it out.

...

I just went out to the bike and slipped the connector off the bottom of the right cylinder and slipped it back on. It's so easy this caveman can do it.
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Old 06-16-2010, 08:47 PM   #29
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Heat will have that sensor out in no time.
Heat it up and yank on it. A well placed knock with a large hammer often helps.
I've done a few, usually take them out after a run when engine is hot. I've never undone the wire harness. Just get a twist in it and repeat the twist to re-install.
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Old 06-16-2010, 08:57 PM   #30
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not trying to hijack the tread, but.....my '98 r1100gs does not have a 02 sensor, nor the hole where it should be, and it's the original cat.....is this a bogus thing ?
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