BMWSportTouring BMWST DB
Previous Thread
Next Thread
Print Thread
Page 61 of 64 1 2 59 60 61 62 63 64
#939084 - 08/05/15 02:00 AM Re: Introduction and O2 Question [Re: roger 04 rt]  
Joined: Aug 2010
Posts: 259
legarem Offline
Member
legarem  Offline
Member

Joined: Aug 2010
Posts: 259
Quebec, Canada
Hi Roger

Every time I do a change I reset the Motronic

#939109 - 08/05/15 10:03 AM Re: Introduction and O2 Question [Re: legarem]  
Joined: Nov 2011
Posts: 2,648
roger 04 rt Offline
Member
roger 04 rt  Offline
Member

Joined: Nov 2011
Posts: 2,648
Naples FL & Cape Cod
Then after removing the second IAT sensor, you should ride for a tank of fuel before assessing pinging, it may improve. Or, since there's no real harm to keeping the second IAT, if you have it located in the airbox or intake, you might just want to enjoy your success.

Since you're riding at an AFR of 12.9, which is lambda=0.88, you need at least 12% more fuel than the fuel table specifies. If you also run fuel with ethanol, you need an additional 4%. This means you want 16% more fuel than your stock fuel table is programmed for to get to 12.9:1 AFR.

Your 3.5 bar regulator (8%) and second IAT (6%) add 14% so you get to about the right point. Your Motronic only needs to add the remaining 2% through adaptation.

Why not just enjoy the ride now?

Last edited by roger 04 rt; 08/05/15 10:04 AM.
#939119 - 08/05/15 12:23 PM Re: Introduction and O2 Question [Re: roger 04 rt]  
Joined: Aug 2010
Posts: 259
legarem Offline
Member
legarem  Offline
Member

Joined: Aug 2010
Posts: 259
Quebec, Canada
Originally Posted By: roger 04 rt

Why not just enjoy the ride now?


Hi Roger

No ethanol gas here unless we really want to choose this gas on some gas stations. My bike has 101 000 kms and fuel tank hoses looked like new last year.

As everything now works as it never worked and I will not know why the pinging is gone. That's what i'll do.

#939433 - 08/10/15 12:32 AM Re: Introduction and O2 Question [Re: roger 04 rt]  
Joined: Aug 2010
Posts: 259
legarem Offline
Member
legarem  Offline
Member

Joined: Aug 2010
Posts: 259
Quebec, Canada
With an AFR of 12.9, I do 42 MPG. That's great

#939452 - 08/10/15 04:15 AM Re: Introduction and O2 Question [Re: legarem]  
Joined: Nov 2004
Posts: 1,281
JamesW Offline
Member
JamesW  Offline
Member

Joined: Nov 2004
Posts: 1,281
Florence, Oregon
Hi Marc,
I could live with that mpg and it is about the same as I get at 12.9 which is 41 mpg.

Thanks for that info.

Last edited by JamesW; 08/10/15 04:17 AM.

James
'93 R1100RSL / '10 FJR1300A
#940018 - 08/17/15 01:05 AM Re: Introduction and O2 Question [Re: roger 04 rt]  
Joined: Aug 2010
Posts: 259
legarem Offline
Member
legarem  Offline
Member

Joined: Aug 2010
Posts: 259
Quebec, Canada
Just done 49,44 MPG today with a tank, two on the bike on country roads at speeds between 60 - 75 MPH. Temperature was 85 F

I'm amazed !

just some rare little hints of high speed pinging. Motor is strong and so smooth. I'm now really in love with this bike.

#942256 - 09/09/15 09:10 PM Re: Introduction and O2 Question [Re: roger 04 rt]  
Joined: Nov 2011
Posts: 2,648
roger 04 rt Offline
Member
roger 04 rt  Offline
Member

Joined: Nov 2011
Posts: 2,648
Naples FL & Cape Cod
Mixture Adaptation, Short/Long Term Trims, ECU Learning Exposed by the GS-911!

The Short Version
The GS-911 now reports long term trims for the BMSK which show beyond a shadow of a doubt that the BMW fueling strategy includes Long Term Trims, learned in Closed Loop by using the stock O2 sensor, which are applied to the entire fuel table. This means that the ECU learns about all fueling errors and most attempts to alter fueling on a stock bike. It learns about fueling changes (other than those made to the O2 sensor) and brings them back to stock.


The Long Version
For the past four years I've been explaining how the Motronic, BMSK and BMSX use the narrowband O2 (lambda) sensor to control combustion AFR in the Closed Loop area of the fuel table to accurate achieve lambda=1 (14.7:1 AFR for gasoline). It also allows those ECUs to learn how much correction is required throughout the Close Loop area and to therefore "learn" long term correction factors (mixture adaptations) that are applied throughout the fuel map--at idle, acceleration, all the way to full throttle--all the time.

Measurements reported throughout this thread have demonstrated the effects of this "learning" and many readers here have come to realize that our BMW motorcycle ECUs perform this powerful function. It allows the ECUs to adapt to changing conditions in the engine as it wears, as the fuel injectors and air filter accumulate deposits, imperfections and errors in all sensors, voltage deviations (even due to a failed alternator), fuel pressure changes, and even adapt to gasoline with ethanol.

This mixture adaptation also limits the ways in which you can alter fueling: modify the air temperature sensor and the ECU corrects fueling. Change the fuel pressure regulator and it learns about and fixes that too. Even modify values in the ECU fuel table in the onboard chip, and it corrects for that. However, alter the O2 sensor for richer or leaner fueling and the ECU obligingly shifts the entire fuel table automatically. (Another way to alter fueling successfully is to disconnect the O2 sensors & add a piggy back controller. This approach puts the ECU into a Limp-Home mode.)

In spite of the Bosch and BMW documentation mentioning mixture adaptation and long term trims, and even given the measurements of it shown in this thread and others, there are still many riders who aren't fully convinced. After all, until now there haven't been any gauges or displays which explicitly show the long term and short term trims at the heart of this "learning" capability.

Recently Hexcode SA, maker of the powerful GS-911 diagnostic tool, have added new realtime values to the long list reported for the BMSK ECU. In addition to the short term trims shown for the Closed Loop area (Lambda Correction Factors 1&2), the GS-911 now reports four new long term trims: Additive Trims 1 & 2 and Multiplicative Trims 1 & 2. The "1" trims are for the right cylinder and the "2" trims are for the left cylinder.

A colleague in the UK who has an R1200GS and owns a GS-911 and dual LM-2s (which can record AFR data and other info for both cylinders) with Wideband O2 sensors added to each exhaust. He took a ride the other day and sent in the LM-2 and GS-911 data, which includes a 13 second wide-open-throttle (WOT) run in 6th gear. This 6th gear "pull” shows for certain that long term trims exist and that they are applied to open loop fueling, right up to WOT.

Have a look at the table below. The data clearly shows the BMSK going open loop (highlighted in yellow) where the lambda control factors set to 1 (set to 1 there is no increase or decrease in fuel due to the immediate values of the O2 sensor) and clearly shows the application of the Long Term Multiplicative Trim at WOT. To understand the Multiplicative Trim, the number in the Injection Time column is multiplied by the number in the Multiplicative Trim column. Taking the first highlighted row, the 10.56 mS injection time is multiplied by 1.12 for the right cylinder and by 1.03 for the left cylinder resulting in Injection Times of 11.8 mS for the right cylinder and 10.9 mS for the left cylinder. In other words, the long term trim learned at lower power levels has been applied to this Open Loop area of fueling.

If you’re surprised that there is this much difference between the left and right cylinders, he confirmed that left and right cylinders had AFRs which tracked each other very closely by making an actual AFR measurement on both cylinders at the same time the GS-911 data was gathered.

Going a bit further, the multiplicative trim is not a single value for the whole but map but a table of values (how many have not yet been determined). There are 5 different long term multiplicative trims in this "pull" between 1800 and 4700 RPM. So the long term trim table is quite a bit larger than we'd expected.

There are also two long term additive trim types, for which there is a corresponding table of values. These additive long term trims affect small throttle angles and idle. The multiplicative trims affect cruising, acceleration and wider throttle angles.

[Summary]
This new GS-911 capability is an exciting development in the understanding of BMWs fueling strategy. It demonstrates clearly the complex ways in which its ECUs process data gathered in the Closed Loop fueling area and apply it to the entire fuel table, including acceleration and starting. At the moment, Hexcode has not added the collection of this data for the newer liquid cooled Boxers or for the older Motronics but the effect of the trims has been accurately measured on all bikes. If you care about this make sure to let Hexcode know that you’d like to see this data for your bikes too. (The BMSK is used on many different BMW bikes including the F800GS.)

As I receive more data from the field, I will add any important insights that are found.



#942519 - 09/13/15 09:52 AM Re: Introduction and O2 Question [Re: roger 04 rt]  
Joined: Nov 2011
Posts: 2,648
roger 04 rt Offline
Member
roger 04 rt  Offline
Member

Joined: Nov 2011
Posts: 2,648
Naples FL & Cape Cod
The bike in the table above shows an average trim of 1.08 for the right cylinder and 1.03 for the left cylinder. He has an AF-XIED installed on setting 7 and has measured it with an LM-2 showing about 6% added fuel.

If you subtracted that 6% from each side the trims would look like 1.02 on the right and 0.97 on the left, suggesting that the right cylinder naturally runs 2% lean and the left runs 3% rich. To me that seems like a reasonable spread. Our R1150s don't have dual O2 sensors so we could expect left right imbalances of this much or greater, which can't be "trimmed out" as on the R1200, a big plus for the 1200.

#942521 - 09/13/15 11:56 AM Re: Introduction and O2 Question [Re: roger 04 rt]  
Joined: Jun 2010
Posts: 14,085
dirtrider Offline
The Oracle
dirtrider  Offline
The Oracle
Member

Joined: Jun 2010
Posts: 14,085
Ohio
Morning Roger

Don't forget that on the 1200 the evap purge hose only hooks to ONE side TB (no crossover hose like on the 1100/1150).

I presume all the 1200 bikes have evaporative emission controls by now.

Be interesting to see if the trims change if the purge hose is moved to the other side TB.


D.R. ___
Sent from my rotory dial wall phone!
#942618 - 09/14/15 02:11 PM Re: Introduction and O2 Question [Re: roger 04 rt]  
Joined: Nov 2011
Posts: 2,648
roger 04 rt Offline
Member
roger 04 rt  Offline
Member

Joined: Nov 2011
Posts: 2,648
Naples FL & Cape Cod
Good morning DR,
You raise an excellent point and I don't know whether the BMSK strategy is to let the Evap Purge change the Long Term Multiplicative Trim or not. The could take one of three approaches: ignore updating the LTMT when the purge is open, update it and let that role into the average, or keep a separate table of "adjustment" trims for the Purge Valve.

One thing we know for sure is that opening the purge does influence the Lamba Control Factors which are short term trims. In the chart below, opening the purge valve at idle results in a change to the idle actuator settings (it closes a little when the valve opens) and AFR (as seen by the LCF adjusting). The LCF reduces from 1.10 at idle with the valve closed to 0.90 with the valve opened, meaning not only does it need less air on the left, but less fuel as well.

I went back and checked the full data set, in the data on trims above, the purge valve was not opened during the WOT or at any time during this UK riders testing. (Do the UK R1200s have canisters?)

Since the Left Cylinder Trim is smaller, it suggests that the mixture on that side is, on average, richer.

All interesting, thanks for mentioning it.
RB


Last edited by roger 04 rt; 09/14/15 02:13 PM.
Page 61 of 64 1 2 59 60 61 62 63 64

Powered by UBB.threads™ PHP Forum Software 7.6.0
Page Time: 0.014s Queries: 14 (0.007s) Memory: 2.8201 MB (Peak: 3.0084 MB) Zlib enabled. Server Time: 2018-07-19 19:18:33 UTC