R1100 Motronic MA 2.2 Functions

[roger 04 rt]

In various threads there have been discussions about the functions of the Motronic MA 2.2 (R1100) compared to the Motronic MA 2.4(R1150). During the testing of my LC-1 Wideband O2 installation, by using its AFR recording capability and the GS-911's real time value recording capability I was able to confirm most of the MA 2.4's fueling functions (block diagram below).

 

As with the Motronic MA 2.4, there is almost no published information on the MA 2.2 used on the 1100s. Since we know that the sensors are virtually identical between the two Motronic versions and since they are both members of the Motronic MA family, I've taken a stab at a draft of the block diagram of the MA 2.2, below.

 

To build the MA 2.2 diagram, the MA 2.4 block diagram was used as a starting point. Then the Open Loop fueling capability was added for the Not CAT Coding Plugs with no catalytic converter and a CO Pot. In yellow highlighting I've identified either capabilities that exist in the 2.2 but not in the 2.4, or capabilities that I've measured on the 2.4 that may or may not exist on the 2.2. I'll comment on them in a moment.

 

The GS-911 doesn't seem to be able to data log realtime values for the MA 2.2 so that inhibits one of the sources used for figuring out the MA 2.4. However, if someone who owns an R1100 installed an LC-1 they would gain the many benefits of running a richer mixture and be able to capture data logs that would enable confirmation of the MA 2.2 functions. I'd be happy to assist in any way that I can. Until then some of the mysteries of the MA 2.2 will remain locked in its source code.

 

Looking at the MA 2.2 diagram's yellow highlighted boxes, here are some open questions:

 

Learn box: Does the MA 2.2 have a silent ability to learn and store the TPS range. It is likely that it doesn't, but it would be interesting to test and confirm this. It does monitor the TPS and can output an error code.

 

Fuel Tables box: What are the target mixtures of the No CAT fuel table? It seems from the CO adjustment Pot spec (1.5% ±0.5%) that it is likely to be richer, perhaps 14.0:1 in the cruising area. This could be easily confirmed with an LC-1.

 

CO Pot/No CAT/Adjust boxes: These functions are in the MA 2.2 but we don't know what they do. For example, does the adjustment add a fixed amount of time or does it add a percentage to all fueling calculations? Is there an RPM limit to this function? When in No CAT mode, is the fueling smoother than the lumpy limp-home fueling of the MA 2.4 with the CAT disconnected?

 

Compare/Adapt boxes: We know the MA 2.2 has all the sensors of the 2.4 and we know that it has a Closed Loop program. Does the MA 2.2 compare the Open Loop and Closed Loop fueling calculations like the 2.4, and thereby compensate for E10 fuel and other wear variations (e.g. air flow, fuel flow, fuel pressure, wear within the combustion chamber)? Or does it lack this capability and should owners of R1100s boost their fuel pressure to compensate, say, for E10's leanness?

 

An LC-1 installed on an R1100 could answer these and other questions.

RB

 

 

[dirtrider]

-- Fuel Tables box: What are the target mixtures of the No CAT fuel table? It seems from the CO adjustment Pot spec (1.5% ±0.5%) that it is likely to be richer, perhaps 14.0:1 in the cruising area. This could be easily confirmed with an LC-1.

 

Evening Roger

 

Good work on that 2.2 diagram.

 

From what I was able to determine working with the Ma 2.2 years ago the Co. trim pot is for idle Co adjustment only. That fits the same European mold of other MA 2.2 era motorcycles (even carbureted) that only had to meet hot street idle Co quality. The old BMW manuals I have also only show idle Co setting on the non Cat 2.2 bikes.

 

Obviously that idle Co adjustment runs up the RPM band a little above idle as idle fueling carries up a bit but I could never see much effect in the cruising operating range.

 

The TPS adjustment could be used to effect some light throttle fueling (subjective) so that would tell us it didn't learn low & high perimeters like the Ma 2.4 does. The automotive Ma 2.2 was a non-learning TPS box.

I haven't ever seen any TPS teaching required for the Motorcycle Ma 2.2 after battery disconnect or power down (not even any BMW service advisory). Common sense tells us that if the TPS was learnable there would have been a teaching enable command that needed to be enabled after Ma 2.2 loss of keep alive power.

 

That 1800 RPM dropped throttle fuel cut off seems a bit high (might be correct though) but on the 1100's I owned & used to work on they were closer to 1500-1600 on the tac.

 

[roger 04 rt]

Hi DR,

 

Idle pulses run about 1.9 milliseconds on the 1150 and are likely the same on the 1100--same RPM range same twice-per-cycle firing--with about a millisecond of dead time. The CO range is 1% to 2% which equates to 14.1:1 to 13.8:1 or about a 2% variation. Two percent of the roughly 1 millisecond the injectors are on means that the CO Pot is changing the fueling about 0.01 to 0.02 mS if I've done the math right. For the adjustment to be effective in all situations maybe they've given it a 0.1 mS total range. They could limit its effect by making that adjustment additive to the calculated pulse. At WOT the pulses grow to 8 mS and fast cruising is less than 4 mS so adding 0.02 mS would have a declining impact if additive. This could be quickly determined with an LC-1.

 

What I'm most interested to learn is, what's the fueling table for the CO Pot configuration? A couple rides with an LC-1 would quickly tell the story since it logs AFR even if it's not connected for Closed Loop. That would tell us something about how BMW wanted to fuel the Oilhead when they weren't constrained by a catalytic converter. From my 1150 testing And the CO spec, i would bet that it is lambda 0.95 at cruise.

 

The TPS question is interesting too. I tend to agree that the Motronic 2.2 doesn't learn the TPS range but that would be pretty easy to confirm with an LC-1 too.

 

For OFC on dropped throttle the numbers could well be different for the 1100. I put 2% throttle and 1800 rpm since that's what I've measured but it's just a starting point.

 

Comparing the block diagrams, what stands out most is how similar the two Motronics are. They use all the same sensors. The biggest difference is that the MA 2.2 has an Open Loop program. The biggest unknown is whether the 2.2 has the Compare/Adapt blocks; I wouldn't bet against it given the similarities.

 

Thanks for your many inputs.

[dirtrider]

Morning Roger

 

On the idle injection pulses-- even if the same between 1100 & 1150 that probably doesn't equate to same fuel delivery.

 

The 1100 & 1150 use different fuel injectors & the 1100 has a little over 10 psi lower nominal fuel pressure.

 

[roger 04 rt]

Morning DR,

So is the nominal pressure 33 psi? I'll make the change to the diagram.

 

I mentioned similar time pulses because the top rpm of 7250 for the 1100 is the same as the 1150. This equates to an 8.28 mS period. So injector pulses can't be longer than that without overlapping (they could be shorter though). Still I believe that 0.1~0.2 mS adjustment range, if it is additive is in the ballpark. (It could be a percent scale factor of a few percent, then it might apply similarly all the way to 8 mS at WOT.)

 

But to your point, even if the same time, it is likely different fuel delivery since different injectors, pressure and 5 HP less.)

 

The idle PW could be easily measured with an oscilloscope. Does anyone know the OEM injector PN (not BMW PN)? I'd like to capture that on the diagram.

RB

 

[dirtrider]

Morning DR,

So is the nominal pressure 33 psi? I'll make the change to the diagram.

 

 

 

 

Morning Roger

 

No, its around 43 psi (I looked on the wrong line of my chart when I said it was 10 psi lower).