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#765027 - 03/11/12 10:43 AM Re: Motronic Long Term Fuel Trim [Re: Peter Parts]
JamesW Offline
Member

Registered: 11/23/04
Posts: 817
Loc: Florence, Oregon
Hello Ben,
I see your point and mostly agree. However, Roger has a very curious mind and he has succeeded in furthering our understanding of just how the motronic works. Also, remember that early on his aim was not to modify how the motronic works but to understand it and work within its parameters to allow it to better perform its function which he has done. He specifically ruled out the Techlusion as it modifies in order to perform its function. My mods to my bike have definitely circumvented the operation of the motronic in that I have disabled closed loop operation and I'm not 100% sure that this is the way to go even though I like the results, so far. Roger has not removed the O2 sensor but has instead installed a superior version which is the wideband sensor which is an improvement on the original narrow band concept, imo. I may yet follow his lead at least with the '04RT.


Edited by JamesW (03/11/12 10:45 AM)

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#765161 - 03/11/12 10:52 PM Re: Motronic Long Term Fuel Trim [Re: JamesW]
roger 04 rt Offline
Member

Registered: 11/27/11
Posts: 1839
Loc: Massachusetts
As an idea how prevalent adaptive lambda control is and when it all began ... Bosch was richly endowed with this technology, early in the game.

From Wikipedia Articles on Bosch Jetronic and Motronic. Adaptive use of Lambda began in the 1980s onward.

[edit]LH-Jetronic (1982–1998)

Digital fuel injection, introduced for California bound 1982 Volvo 240 models. The 'LH' stands for German: "Luftmasse-Hitzdraht" - the hotwire anemometer technology used to determine the mass of air into the engine. This air mass meter is called HLM2 (Hitzdraht-LuftMassenmesser 2) by Bosch. The LH-Jetronic was mostly used by Scandinavian car manufacturers, and by sports and luxury cars produced in small quantities, such as Porsche 928. The most common variants are LH 2.2, which uses an Intel 8049 (MCS-48) microcontroller, and usually a 4 kB programme memory, and LH 2.4, which uses a Siemens 80535 microcontroller (a variant of Intel's 8051/MCS-51 architecture) and 32 kB programme memory based on the 27C256 chip. LH-Jetronic 2.4 has adaptive lambda control, and support for a variety of advanced features; incincluding fuel enrichment based on exhaust gas temperature (ex. Volvo B204GT/B204FT engines). Some later (post-1995) versions contain hardware support for first generation diagnostics according to ISO 9141 (a.k.a. OBD-II) and immobiliser functions. The 1995 and newer Volvo 940 vehicles are one such example.

[edit]ML1.1
The Motronic 1.1 System was used by BMW from 1987 on motors such as the M20.
The systems have the option for a lambda sensor, enabling their use with catalytic converter-equipped vehicles. This feedback system allows the system analyse exhaust emissions so that fuel and spark can be continually optimised to minimise emissions. Also present is adaptive circuitry, which adjusts for changes in an engine's characteristics over time. Some PSA engines also include a knock sensor for ignition timing adjustment[4], perhaps this was achieved using an external Knock Control Regulator.

[edit]Mono-Jetronic (1988–1995)

Digital fuel injection. This system features one centrally positioned fuel injection nozzle. In the US, this kind of single-point injection was marketed as 'throttle body injection' (TBI, by GM), or 'central fuel injection' (CFI, by Ford).
Mono-Jetronic is different from all other known single-point systems, in that it only relies on a throttle position sensor for judging the engine load. There are no sensors for air flow, or intake manifold vacuum. Mono-Jetronic always had adaptive closed-loop lambda control, and due to the simple engine load sensing, it is heavily dependent on the lambda sensor for correct functioning.


Edited by roger 04 rt (03/11/12 11:21 PM)

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#765169 - 03/11/12 11:24 PM Re: Motronic Long Term Fuel Trim [Re: roger 04 rt]
Peter Parts Offline
Member

Registered: 09/01/09
Posts: 1824
Loc: Toronto and Delray Beach, FL
We're back to parsing texts.

As I mentioned earlier, all feedback loops are adaptive systems. I see nothing in those texts or in the operation of the crude Motronic that obliges me to think there is more. Maybe there is more and maybe there isn't. And as far as I can see, which isn't far, there is no need to posit "learning" besides the TPS anchors.

Doesn't anybody know for sure? How come after all these years, nobody is privy to the Motronic block diagram?

I certainly don't know.

Ben


Edited by Peter Parts (03/11/12 11:26 PM)
_________________________
R1100S, 1999 (don't know much about other models)
Riding 52 years but only last 47 on BMW boxers
Bike writings: http://www.tinyurl.com/6bvt23
(includes a 6400 mile trip, 20 days, with wife to LA)

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#765172 - 03/11/12 11:38 PM Re: Motronic Long Term Fuel Trim [Re: Peter Parts]
roger 04 rt Offline
Member

Registered: 11/27/11
Posts: 1839
Loc: Massachusetts
Ben,
There are many readers here. I understand what You see but from many weights of evidence for and the lack of any evidence against, it is clear that these ECUs are learning adapting systems.

For those who want to think about changes to their systems, I hope this is all useful background to select good, cost-effective changes.

...

And if it's not your cup of tea, that's okay. As they say, YMMV
RB

And PS, the block diagrams are in the Bosch Automotive Handbooks.


Edited by roger 04 rt (03/11/12 11:40 PM)

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#773214 - 04/23/12 08:29 AM Re: Motronic Long Term Fuel Trim [Re: roger 04 rt]
roger 04 rt Offline
Member

Registered: 11/27/11
Posts: 1839
Loc: Massachusetts
I've been running with an LC-1 and BoosterPlug, kind of a belt and suspenders approach. The LC-1 for Closed Loop and the BoosterPlug for Open Loop. For some time I have wanted to see how the LC-1 and Motronic performed without the BP shifting the stock Open Loop AFR tables 6% richer because I know that Adaptation Values get built from Closed Loop and get applied to Open Loop. Confirming it worked that way would mean that the BoosterPlug was a nice-to-have (since I own one), not a need-to-have.

A key to these tests is a cold start, watching how the Motronic and LC-1 transition from cold (enriched and Open Loop) to warm (no afterstart or warmup enrichments, and Closed Loop). Therefore both tests were begun immediately after start and on the same course. (Note: In the upper chart, second half, I was modulating the throttle more than in the second half of the bottom chart. Otherwise, they are for the same course.)

I got out for the first two of several rides. In the attached photo, you can see the first ride (top chart) after the Motronic is reset with no BP, and then a day later, the second ride. In the first ride after reset (in my theory, before the Adaptation Values referred to in the BMW Service manual can be rebuilt) you can see a lot of deviations from 13.8:1. If you look carefully on the left of the top chart you can see the mixture starting at about 12:1 and then watch what happens while the bike warms up at about the 3 minute mark (same point below). You can also see the histogram on the right, it being the distribution of all AFRs during the ride.

In the below chart, second ride from a cold start, you can see better adherence to 13.8 and a tighter histogram. (Ignore the spikes that go to the top of the chart, they are Overrun Fuel Cutoff.) It also gets to 13.8 right away, before the bike has warmed up and before it can be in Closed Loop, in the first minute or so. (Notice the dips to lower AFRs, that's where I'm shifting!) The only surprise in the lower chart is the blip to 14.7:1 (Open Loop target AFR of the reset Motronic) between 1:40 and 3:20 minutes. This was after a stop sign and reacceleration, before CL had started and perhaps (my deduction) in an area of the Adaptation Values table that had not built sufficient data yet.

I plan to make many more rides and watch this closely and will have some more data over the coming weeks.
RB

In the photo, there are two horizonal dotted lines. The top line is 14.7:1 (Open Loop Table before Adaptation) and the bottom line is at 13.8:1 (My AFR target set by the LC-1).




Edited by roger 04 rt (04/23/12 08:48 AM)

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