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Old 05-23-2013, 02:59 PM   #421
ebrabaek OP
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Originally Posted by roger 04 rt View Post
The fact that you needed more fuel to get the same good idle says that you're getting more air in the cylinder at idle with SAS off!
Must be, as either the PC-5 or AT was active at idle with the SAS on.
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Old 05-23-2013, 10:01 PM   #422
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Originally Posted by roger 04 rt View Post
The fact that you needed more fuel to get the same good idle says that you're getting more air in the cylinder at idle with SAS off!
Just a thought excercise here. Could the closed loop operation with the SAS, even though it won't use the O2 sensor signal, richen the idle mixture more than the open loop operation. Thus when ebrabaek disconnects the SAS, the ECU stops providing more fuel at idle, and the PC5 has to compensate more than previous operation.

To my thinking when the ECU doen't have the use of the O2 sensor or the SAS, the maps it has loaded are less precise so now the PC5 has to compensate more. The nice thing is the PC5/AT is pretty good, possibly better at maping AFR requirements of the engine.

We did a test on an industrial engine once, measureing the Emissions pre and post catalyst. The exhaust is an 8" diameter pipe. We had a port 5 feet before our pre/cat measureing point, and it had a 1/4" tubing fitting with a cap. If we opened the cap on this fitting the O2 we were measuring went from 0.5% to 1.2% which made the fuel controller go into an error mode. If you held your hand over the fitting, you always felt exhaust blowing against your hand.

David
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Old 05-23-2013, 10:24 PM   #423
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It is interesting you bring this up David, as I was about to suggest sort of the same. Gents..... Unless I find anything way out of whack in the morning after I download the Trims, I am restoring the bike to it's earlier stage with the SAS on. More on this in the morning.... hundred miles.....50mph dust storm..... Tired.
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Old 05-24-2013, 04:01 AM   #424
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Originally Posted by MTrider16
Thus when ebrabaek disconnects the SAS, the ECU stops providing more fuel at idle, and the PC5 has to compensate more than previous operation.
...even if the connector is in and the hose plugged? Don't think so.
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Old 05-24-2013, 06:22 AM   #425
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A friend in automotive design, with a lot of motorcycle tuning commented to me on the difficulty of tuning an engine when there's a lot of air reversion going on. One of the ways to diminish the effect of reversion would be to leave much of your exhaust as it it but add the catalytic converter back in as a reversion-break, effectively keeping fresh air from getting back to the O2 sensor.

It's probably not the direction you want to go but it might allow Autotune to be more effective for you. Just a thought ...


Quote:
Originally Posted by ebrabaek View Post
It is interesting you bring this up David, as I was about to suggest sort of the same. Gents..... Unless I find anything way out of whack in the morning after I download the Trims, I am restoring the bike to it's earlier stage with the SAS on. More on this in the morning.... hundred miles.....50mph dust storm..... Tired.
I can understand why you want to return to the configuration that was working better. However, it seems like with SAS enabled you have less air filling the cylinder at certain rpms which says that you will have lower VE and lower ultimate torque potential in any rpm/TPS cells that are affected—although it would take further tuning to access that torque.

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Originally Posted by Gaspare View Post
...even if the connector is in and the hose plugged? Don't think so.
You're right. The ECU is unchanged. What EB has done is to give us all a very powerful demonstration of the degree to which a change in exhaust configuration can change the VE (volumetric efficiency) and hence the AFR of an engine.

Disabling SAS allowed the cylinder at idle to fill more efficiently. It is likely that there will be more air in the cylinder at other points too. More air means more power once the fueling is corrected, as demonstrated by the improved idle.

Quote:
Originally Posted by MTrider16 View Post
Just a thought excercise here. Could the closed loop operation with the SAS, even though it won't use the O2 sensor signal, richen the idle mixture more than the open loop operation. Thus when ebrabaek disconnects the SAS, the ECU stops providing more fuel at idle, and the PC5 has to compensate more than previous operation.

To my thinking when the ECU doen't have the use of the O2 sensor or the SAS, the maps it has loaded are less precise so now the PC5 has to compensate more. The nice thing is the PC5/AT is pretty good, possibly better at maping AFR requirements of the engine.

We did a test on an industrial engine once, measureing the Emissions pre and post catalyst. The exhaust is an 8" diameter pipe. We had a port 5 feet before our pre/cat measureing point, and it had a 1/4" tubing fitting with a cap. If we opened the cap on this fitting the O2 we were measuring went from 0.5% to 1.2% which made the fuel controller go into an error mode. If you held your hand over the fitting, you always felt exhaust blowing against your hand.

David

Some interesting info here. A 1/4 inch hole in an 8" pipe, seems tiny at first. Although all you could feel was a net outflow at the 1/4" tube, clearly, there was an inflow of fresh air, as measured by the O2 increase at the sensor. EB's results and your example show the possible impacts of exhaust changes on performance.

Your example and this sas result suggest that Autotune will handle some of the adjustment on its own and some will need hand tuning.

To your question, the BMSK, once the O2 was disconnected, has no knowledge of the changing AFR impact of SAS, exhaust or PCV fueling. The BMSK is in the blind and calculates fueling by going to a lookup table with rpm and TPS info, then adjusting that value for battery voltage, intake air temperature and barometric pressure. Then to that fueling number it applies Adaptation Value corrections learned long ago, unless the Adaptations were reset at some point.

roger 04 rt screwed with this post 05-24-2013 at 06:33 AM
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Old 05-24-2013, 06:47 AM   #426
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Originally Posted by roger 04 rt View Post
A friend in automotive design, with a lot of motorcycle tuning commented to me on the difficulty of tuning an engine when there's a lot of air reversion going on. One of the ways to diminish the effect of reversion would be to leave much of your exhaust as it it but add the catalytic converter back in as a reversion-break, effectively keeping fresh air from getting back to the O2 sensor.

It's probably not the direction you want to go but it might allow Autotune to be more effective for you. Just a thought ...
I personally don't think it is air reversion. I cannot prove it, but usually when that has been the case you can hear the motor gurgle, and pop quite a bit. So here is a summery after a little over 100 miles.

SAS ON..... bike runs fantastic.... smooth idle, and although you can still make out a few diminished dead bands in the power band, the bike pulls strong in all gears.

SAS OFF.... Buke first stumbled at all rpms, but specially beginning at about 4000 rpm, getting worse at 5500-6000 rpm, and fall flat above 7000 rpm. Idle is rough. This seems to more noticeable in 4,5, and 6'th gear. I kid you not, but it is. We are beyond Erling being a noob tuner.....butt dyno....etc. This is not the first bike I have worked with, so although I cannot tell you how much difference there is.....there IS a noticeable difference. Some of the difference was corrected with a new base map accepting the trims inputtet from the AT model, but it did not take care of the 3000-8000 rpm WOT pull, in 4-5-6 gear. Some times, it did even not accelerate past 90 mph.....

I am not arguing the disability of the SAS. I truly am not. But it is like the motor is telling me, simply put, it does not like this. A 13.2 AFR is maintained constantly by the AT ( I know...I know....error with SAS ON) but I have worked on PAIR systems before, and as my tuner said..... It is normally a little difference, but if it is showing a detrimental value, then there is something else going on there. Then I started about the bike specifics. Mine is an 2009 with original BMS-K software load. No updates..... Why am I showing such great runs with the SAS ON, and others here do not.... Gaspare, has his BMS-K reflashed, and as such cann really not compare the two in their operational stage. SOP Dirt Rider...... Not sure why his is behaving different. Dont get me wrong, it is still running ok, until you push the bike real hard. Possible causes, and they are nothing more than stabs..... When SAS is turned off the BMS-K knows it somehow...( I thought I read somewhere that Joel said with the SAS off, the BMS-K throws error messages) and somehow does something in the pulse length...... amplitude, or something other why detrimental to the fueling, than the AT cannot correct. Due to the tone change..... I was even thinking about that perhaps if there are any errors in the BMS-K, it retards the ignition, or stops advancing the ignition...... I know.... crap shoot, but I am convinced that something is going astray when the SAS is turned off ON MY BIKE. So I will have a look at the trim tables today, and off course if I see anything in there, as a concern, I will post it, but I am afraid my testing is done, until we get someone with bike specific knowledge to chime in. I will gladly do back, and try things, if need be in the future, but as I have said in the beginning, I simply cannot argue with success. My bike rips with the SAS on, and such I shall return it. Sorry.
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Old 05-24-2013, 07:53 AM   #427
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You could rule you the BMSK knowing, very simply. Leave the connector attached but plug the line. Then for sure, the BMSK won't/can't know. If you did that experiement then we'd know if no SAS disconnected does throw an error and Limp Home signals.

I think air reversion still has to be considered because of the large (>20%) fueling additions. That's the simple version.

Having made both those comments, I genuinely understand where you're at and the decision to run it as is since it runs so well. To an extent, we've been learning while you're doing all the work and bearing all the responsibility.

My thought was simply that if you got it to the point where Autotune was producing smaller numbers that weren't effected either by air reversion or SAS O2 in the exhaust, you might have a more stable long term solution and one which adapted better to things like the changing ethanol content in fuel you purchase. I'm sure everyone will continue to monitor your progress and offer their thoughts when needed.

RB
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Old 05-24-2013, 08:12 AM   #428
ebrabaek OP
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Originally Posted by roger 04 rt View Post
You could rule you the BMSK knowing, very simply. Leave the connector attached but plug the line. Then for sure, the BMSK won't/can't know. If you did that experiement then we'd know if no SAS disconnected does throw an error and Limp Home signals.
That's what I thought Roger, but I have tried both plugging the line, and are not running with the pluming connected, but the electrical plug disconnected..... Dunno.


I think air reversion still has to be considered because of the large (>20%) fueling additions. That's the simple version.

Having made both those comments, I genuinely understand where you're at and the decision to run it as is since it runs so well. To an extent, we've been learning while you're doing all the work and bearing all the responsibility.

My thought was simply that if you got it to the point where Autotune was producing smaller numbers that weren't effected either by air reversion or SAS O2 in the exhaust, you might have a more stable long term solution and one which adapted better to things like the changing ethanol content in fuel you purchase. I'm sure everyone will continue to monitor your progress and offer their thoughts when needed.

RB
I will look, after my mountain bike ride, but I dont excpect to see any large numbers.... I will post the trim table.
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Old 05-24-2013, 03:20 PM   #429
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And so went the 8GS back with the SAS on, and zero map loaded....Trims zeroed out, ready for riding..... In the mean time, here are the last set of AT trims with after a bit over 100 miles...... Not bad....



Then trims added to the base map......



Just FYI off course, as I have returned the bike to Fantastic Land..... From here on out, I will ride for at least 100 miles before I accept the trims. Mind you I never accepted the trims since install with SAS on...... We shall see.

Cheers......
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Old 05-25-2013, 10:41 AM   #430
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I can see why SAS ON would reduce air reversion (even as it feeds air into the exhaust stream) by reducing the low pressure area as the exhaust valve closes. So with SAS disabled as with the above trims you may get a larger air infiltration from revision leading to some of the large numbers in the table.

Here are some comments from DynoJet:
airfuel
05-12-2009, 11:14 AM
Air reversion is when the exhaust pulse pulls fresh air into the exhaust system giving a false lean reading. Mostly big twins run into this problem but other bikes can also get this when the exhaust velocity is slower at lower revs.

DynojetResearch
05-12-2009, 11:27 AM
Easiest way for you guys to check for reversion. Get the bike connected to a computer and have the software open so you can view the real time AFR. Once the bike is warmed up and the software is reading AFR take a wet towel and block the majority of the exhaust output. Not enough so the bike stalls obviously but a fair bit. If you see the reading change dramatically then you probably have reversion. Also a little common sense, if the software reads 18:1 then you know this is impossible and you need to start looking for why
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Old 05-25-2013, 12:46 PM   #431
ebrabaek OP
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Originally Posted by roger 04 rt View Post
I can see why SAS ON would reduce air reversion (even as it feeds air into the exhaust stream) by reducing the low pressure area as the exhaust valve closes. So with SAS disabled as with the above trims you may get a larger air infiltration from revision leading to some of the large numbers in the table.

Here are some comments from DynoJet:
airfuel
05-12-2009, 11:14 AM
Air reversion is when the exhaust pulse pulls fresh air into the exhaust system giving a false lean reading. Mostly big twins run into this problem but other bikes can also get this when the exhaust velocity is slower at lower revs.

DynojetResearch
05-12-2009, 11:27 AM
Easiest way for you guys to check for reversion. Get the bike connected to a computer and have the software open so you can view the real time AFR. Once the bike is warmed up and the software is reading AFR take a wet towel and block the majority of the exhaust output. Not enough so the bike stalls obviously but a fair bit. If you see the reading change dramatically then you probably have reversion. Also a little common sense, if the software reads 18:1 then you know this is impossible and you need to start looking for why
I personally don't think that the cause is air reversion, but as with any suggestions...... when you have someone involved with more knowledge than one self, I'd be an idiot if I disregard your suggestion. I will try the wet towel trial in a few minutes. Another thing is, that as this is now a 100% open system, with no spark arrestor... (CAT served as one...) I need to make a mesh filter in the exit of the pipe, to be legal USFS. In case you want to know more about the HDCW exhaust I have on it.... It can be seen here.....
http://advrider.com/forums/showthread.php?t=783641
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Old 05-25-2013, 01:09 PM   #432
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There were 1/10'th variation in the idle AFR. That would be too small of a change in the AFR to alert me towards reversion air. Bike just likes this magic BMW SAS being active, me thinks. I am hoping that one day Joel would see this thread, and explain that the SAS really consist of a flux capacitor, and Photon torpedo's..... Gotta be somming like'at......

( PS) video of air reversion test uploading to you tube at the moment. Be here shortly.
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Old 05-25-2013, 02:17 PM   #433
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Video of the Air Reversion Test......
">
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Old 05-25-2013, 06:23 PM   #434
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Hey EB

First, thank you for being a trooper throughout this process, we certainly appreciate it. You have been a really good sport.

I wish we could understand why your bike likes the SAS and others disconnect it as Dynojet says but I also understand your decision to go back to where it was running the best for you.

Another great video, very interesting. I see your bike likes to idle around Stoich as the A/F R seems to be around 14.7 or a little above. I cannot recall the A/F R with the SAS plugged but your bike seems to be happy there.

Again, thank you and enjoy your trip to Europe.

Be well.

Terry
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Old 05-25-2013, 06:49 PM   #435
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Hey EB

First, thank you for being a trooper throughout this process, we certainly appreciate it. You have been a really good sport.

I wish we could understand why your bike likes the SAS and others disconnect it as Dynojet says but I also understand your decision to go back to where it was running the best for you.

Another great video, very interesting. I see your bike likes to idle around Stoich as the A/F R seems to be around 14.7 or a little above. I cannot recall the A/F R with the SAS plugged but your bike seems to be happy there.

Again, thank you and enjoy your trip to Europe.

Be well.



Terry
Thank you as well, for being a good sport through out this as well Terry. During idle there are no input from the PC-5, or AT, and I suppose that the BMS-K somehow controls it about there. I guess with the SAS OFF it runs leaner, at 15-16 AFR..... Many things to think about here. Funny thing was as soon as I set everything back to Zero map....with the idle hop corrected...... Bike was like....hey you, nice to be back..... Ran like a charm. No BMS-K relearn.....just sort of like, where have you been. I am puzzled, as Roger correctly pointed out, that with the SAS off, by idling at a higher AFR it would lead you to think that more air is drawn in. I am starting to think that this somehow a little different SAS on the 8GS, somehow is effectively enhancing the exhaust pulses, to benefit the overall performance. I think we have just about ruled out that the BMS-K is limping, as the SAS hose have been plugged...... dc side unplugged, with same results. I have still yet to fill it up, but are expecting a higher than normal fuel consumption as well. I will report back on this. In the end, I will have to recommend that people that install the PC-5/AT combo on the 8GS, to LEAVE THE SAS ON. I know it goes against all that we know, and I really wish someone could validate this by a few dyno runs....with it on , and off. That said, It has been fun to experiment, even as we have not always agreed on principles.... It have been a great learning experience to me. That I can say with certainty. Hopefully some day we will know....... Lukas.... you have any friends that might know...... Or are you all grinning sipping fine Chezh beer....thinking" I told you so".....
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