Ethanol or lower grade?

[dirtrider]

Morning Ben

 

I doubt the BMS-K learns much about spark knock control as there would be no real reason to & it would be very difficult to implement.

 

The fueling computer definitely learns some short term & long term fueling adaptives based on the twin 02 sensor input. There is also a chance there is some learned short term spark table trims based on the fueling (& possibly) the number of knock sensor interventions.

 

In any case there would be no reason for stored spark learn past the current run cycle unless the spark trim is using some of the fueling adaptives vs TPS for a basic cell position.

 

[Peter Parts]

Morning Ben

 

I doubt the BMS-K learns much about spark knock control as there would be no real reason to & it would be very difficult to implement.

 

The fueling computer definitely learns some short term & long term fueling adaptives based on the twin 02 sensor input. There is also a chance there is some learned short term spark table trims based on the fueling (& possibly) the number of knock sensor interventions.

 

In any case there would be no reason for stored spark learn past the current run cycle unless the spark trim is using some of the fueling adaptives vs TPS for a basic cell position.

 

DR - thanks for clarification although I am not sure why you say it can learn some of those things but not others.

 

But the real hurdle in believing is what is the logic. Can anybody outline the logic that the black box uses? How can the ECU know something is happening? What kind of decision rules are used? How can it coordinate with the other inputs it uses to determine fueling and spark? And so on.

 

(The ECU can't detect/judge/compare things people easily can like, "...ummm, seems to have low power today" or more power today or "won't lug like usual" or rev like usual or "exhaust smells funny" or "engine seems a bit hotter than I'd expect after that bit of riding". People with no programming experience can attribute all kinds of human-like smarts to machines which are unfeasible to achieve in a machine.)

 

Machines can do clever-seeming things and often in simple ways - so I'd like to learn how ECUs do their tricks.

 

Ben

[Paul Mihalka]

"Machines can do clever-seeming things and often in simple ways - so I'd like to learn how ECUs do their tricks."

 

Let's not forget that machines can't do anything humans have not taught them. Too bad we don't have a link to those humans...

 

[dirtrider]

 

 

 

 

Morning Ben

 

In a nut shell the fueling computer learns from past events.

 

As a "simple" example-- If the last time it went from open loop sensor trimmed fueling into closed loop 02 controlled fueling @ 14.7:1 closed loop, if had to instantly decrease the injector pulse width a great deal to get the fueling to 14.7:1 it knows that is was adding more fuel than it needed to in that open loop trimmed fueling box (called a cell). So it makes a small adjustment in the open loop fueling pulse width at that engine load/RPM & remembers that as a learned trim off set (in that particular engine loading/RPM range). Then the next time it is at that same engine load/RPM it basically uses that "block learn" (or in BMW talk adaptive) to off set the open loop fueling the amount it learned.

 

Then the next time it goes into open loop from closed loop at the same RPM/engine load "range" it applies that learned offset to the open loop fueling tables.

 

On the next time it enters closed-loop from that RPM/engine loading it learns the offset again. It keeps doing this for each engine loading/RPM range cell (not for each 1 RPM difference) until the open loop fueling is very close to what the closed loop fueling would be under the same engine loading/RPM range. (continually learns from the 02 sensor as it goes)

 

There are both long term fueling "block learn" (BMW talk) adaptives), maybe a second or so between updates & short term (integrator) (fast, how fast) (maybe 15-20 times a second), I really don't know. The short term is updated continually & the long term a bit slower. As far as I know (this is based on automotive systems & runability differences after clearing the BMS-K learned adaptives) the long term is remembered at key off in the keep alive memory & the short term is cleared at each key off.

 

If it didn't have the short & long term learning ability there could be a major fueling change as it goes into & out of closed loop with a noticeable change in engine runability & smooth transparent fueling control.

Could you imagine riding along at steady throttle & have the system go from 14.7:1 closed loop into 12.5:1 open loop fueling then back into closed loop 14:7:1 again. Talk about a surge.

 

The closer the open loop fueling is at closed loop entry the more seamless the engine operates as it goes into & out of closed loop fueling control.

 

It's a bit more complex than I made it out to be but the basic operation is explained.

 

[Joe Frickin' Friday]

Parsing the exact meaning and the TRUE meaning of something from a vehicle manufacturer is tricky.

 

:confused:

 

What's tricky about the sentence "Use unleaded regular gasoline wiht an octane rating of at least 87 AKI"? How many ways are there to parse that?

 

Nissan and BMW may have their own good or bad reasons for what they write and the message they mean to convey to various audiences (of which users are only one even if you think it is written just for little old you)

 

For what audiences - other than the owner - might the owner's manual have been written?

 

No matter what BMW or Nissan says, it is plain wrong design or to drive your engine to the brink of destruction and expect the safety controls to save you over and over. Not Three Mile Island nuclear plant, you know.

 

There are plenty of parts on the bike that would cause disaster if they failed. Oil pressure sensor and oil thermostat, just to name a couple. FWIW, knock isn't an all-or-nothing thing, either. A single detonation event - even a severe one - won't destroy (or even damage) the engine. It takes prolonged pounding to dump enough heat into the head and piston to start doing damage, and you're gonna hear it if that's happening. Occasional minor pinging isn't a problem, and in fact used to be called "the sound of economy" because it meant that your engine was operating with the ignition as advanced as it could safely be, providing the most efficient operation possible.

[Peter Parts]

Nissan and BMW may have their own good or bad reasons for what they write and the message they mean to convey to various audiences (of which users are only one even if you think it is written just for little old you)

 

For what audiences - other than the owner - might the owner's manual have been written?

 

EU regulators, US gov't testers, California regulators, consumer groups, magazine reviewers, prospective buyers of the model, internal BMW corporate politicians, various import divisions around the world, global game-playing with oil companies...

 

BMW can't have one recommendation in the User Manual and a different one for other purposes.

 

Although BMW might strive for Truth and Purity in their texts, I think the bulk (but not all) of pressures tends to make them want to shade towards saying lower octane (and hence, economy) is OK.

 

B.

[Witch_Doctor]

Remember the owners manuals are written as a universal guide to their vehicle, and are heavily audited by the companies legal departments as CYA for themselves. To believe otherwise is foolish.

[lkchris]

Remember the owners manuals are written as a universal guide to their vehicle, and are heavily audited by the companies legal departments as CYA for themselves. To believe otherwise is foolish.

 

No, frankly to believe as you do is foolish. Not everybody's out to get you.

[Peter Parts]

Remember the owners manuals are written as a universal guide to their vehicle, and are heavily audited by the companies legal departments as CYA for themselves. To believe otherwise is foolish.

 

No, frankly to believe as you do is foolish. Not everybody's out to get you.

 

C'mon Kent, recognizing that corporate lawyers review these texts - and likely have the final say on what goes out under the BMW name - is hardly paranoid in the least.

 

I thought Witchdoctor made a valuable point. And he certainly didn't say or imply that was necessarily user-hostile. All these "audiences" have legitimate reasons for scrutinizing the specs and, fair enough, for BMW to struggle to find the best way to say things, consistent with their own profit-urge.

 

BTW, are you the one who has infinite faith in German engineering Purity and Truth?

 

Ben

[lkchris]

Lawyers blah blah

 

Any ethical and competent engineer knows all about liability and is quite concerned about it and lives with it every waking moment of their life.

 

But, to fantasize (or rationalize) that an owners manual specification that premium fuel be used is a CYA thing is ludicrous.

 

I'd suggest that the chance that a lawyer had any affect on an owners manual fuel specification is ZERO.

 

And, it's simply delusional to think one knows better than those who designed the equipment. Frankly, anyone that educated/experienced would have a better job, perhaps designing motorcycles themselves.

 

So, let's see: German engineers are fools because they've accidentally designed an engine that will run on low-test fuel but instead insist on premium for some conspiratorial reason? Yes, and "Ice Road Truckers" is history made every day.

[RAMBLIN RED]

WHEW!!!!!! to deep for me... So clean this up for me.

My 96 R11RT, almost old enough to vote, has a compression ratio of 10.7 runs fine on 89 octane. Is it ok to run 87?

[Paul Mihalka]

Except when doing Reg Pridmore CLASS track schools, my '99 R1100RT all it got was 87, for 175K miles - then sold in good shape...

[RTJohn]

I started reading and was hooked. I'm going to make sure my colleagues read this. Thanks.

[RTJohn]

My owners manual says to use 91 octane. It says 89 octane can be used but to expect lower performance and fuel economy. There is no mention, at all, of using 87 octane gasoline.

[dirtrider]

My owners manual says to use 91 octane. It says 89 octane can be used but to expect lower performance and fuel economy. There is no mention, at all, of using 87 octane gasoline.

 

Morning John

 

Your 2010 RT uses engine knock sensors to prevent damaging the engine if low octane fuel is used.

 

On RAMBLIN RED's 96 1100 RT there are NO knock sensors used to prevent engine damage so if he uses fuel with too low of an octane & doesn't hear the knocking he could damage his engine from prolonged spark knocking.

 

[RAMBLIN RED]

Thanks D.R.

that resolves the issue for me. No lower than 89 to be safe

[ragtoplvr]

in the winter I can run 87. Last summer, it liked 93. of course we had 100+ degree days! If you can not feel what the engine likes, I suggest you spend the extra.

 

Rod

[Witch_Doctor]

Lawyers blah blah

 

Any ethical and competent engineer knows all about liability and is quite concerned about it and lives with it every waking moment of their life.

 

But, to fantasize (or rationalize) that an owners manual specification that premium fuel be used is a CYA thing is ludicrous.

 

I'd suggest that the chance that a lawyer had any affect on an owners manual fuel specification is ZERO.

 

And, it's simply delusional to think one knows better than those who designed the equipment. Frankly, anyone that educated/experienced would have a better job, perhaps designing motorcycles themselves.

 

So, let's see: German engineers are fools because they've accidentally designed an engine that will run on low-test fuel but instead insist on premium for some conspiratorial reason? Yes, and "Ice Road Truckers" is history made every day.

 

I worked on the FJ project prior its release, and can tell you unequivically, that the Legal Department had final say in anything that was released. That went from Engineering down to Marketing. They have a responsability to protect the company's brand and image, and that scrutiny is a necessity. Its not being paranoid, its simply pragmatic. Just saying based on personal experiance in the industry.

[nbooth]

So, some of you who live near water will be familiar with "recreational" fuel which is 90 octane regular gas (no e10). This fuel is used in boating where it's critical to minimize separation of fuel/water. Regional oil distributors may offer recreational fuel to consumers. It's a tad more expensive, but may be worth looking into. I found a supplier in Florida and now use this fuel in my 09 Suzuki 1250 Bandit. I'm sure it would work in the 05 R1200RT equally as well.

[dirtrider]

Morning Nbooth

 

Yes, a lot of marinas carry alcohol free gas. You just have to be very careful that it is NO LEAD. Some of those marine regulars are leaded gasoline & that will kill the cat converter & 02 sensor in very short order.