I know one of the DIP switches can turn off ALL baro sensors for a 'limp home mode'. But most ECU's will also automatically (and temporarily) ignore any individual sensor that, for example, reports 0 or 5 volts, and substitute a fair assumption. I would think that is a pretty good idea. I know of the term code bloat but I think this is not bloating..

For the O2 sensor, this is even more important. For that sensor, an alternative is to just detect "not changing at all" for a given time, and automatically go open loop. The default LC-1 settings is to go to high impedance state at warm up and at error conditions. I had it set to output 0 volts at error for easier noticing of problems. Last summer it errored out while I did some spirited riding in Germany, unfortunately in Autotune mode. I'm not sure how much it messed up my map before I noticed the very lean running.

After that I set it to output 5 volts at error instead, since a 25% rich mixture wont hurt the engine. A couple of days ago it errored out again and no harm done (this time I wasn't even in Autotune). Still, it would have been nice if the ECU would stop believing an O2 sensor that does not change at all in several seconds.

As a side note, the bike ran surprisingly well at 25% rich  :)

I think this would remarkably slow down the code, doing all this comparisons and things. I bought a WO2 DIY unit nearly 5 years ago and never had a single O2 probe failure so far. Instead I'd be very pissed if I had a slow firmware over all these years. If you push the engine beyond 8000 the ecu already now has all hands full with things to be done.

Just my 5 cents anyway.

Hubert

Huberts sensor never failed, so noone will ever need input checking?

I doubt the CPU is anywhere near its limit performance wise. What makes you think that? And if we keep it at just watching for 0 or 5 volts (missing or shorted sensor), it's extremely little work for the ECU. A couple of lines assembler, dead simple integer comparison. No calculations involved. Depending on how Cliff layed out his software, it may not even have to be performed at every single engine revolution.

Any sensor can fail, and handling that is clever. If it actually can't be done for whatever reason, fair enough. It was just a suggestion.

Besides any added O2 sensor,
does this mean that a failing sensor makes the engine stop/run badly?

And only way to fix this on the road is flipping Switch 2 to off?
From user manual:

Quote:

SW2 - Disable engine sensors. Setting this to on will cause MyECU to ignore oil temperature, air temperature and air pressure inputs. This switch is normally off but could be turned on if one or more of the sensors failed. Cold starts will be affected as no choking will be performed. Closed loop operation with this switch on should work OK except in extremes of altitude and temperature as closed loop operation with only adjust the map by 25%

MyECU has no Limp Home Mode besides that option?

I think raz asked a fair question. ;)

Luhbo wrote on 06/30/09 at 15:33:02:

BTW: why did Raz call the thread "Limp home mode"? What's the problem with running the engine open loop?

Because I was not talking about O2 sensor only, but also the two temperature sensors and the air pressure sensor, ie all sensors that you can substitute a fair assumption for. Obviously we can't ever assume a value for the cam sensor.

If the oil temp or air pressure sensor goes bad, for example, you will have very good results if the ECU substitutes 1000 mbar or 60 degrees. If my alternative is to flick switch 2, the ECU will also stop reading the sensors that work fine.

I wouldn't be surprised at all if Cliff had answered some of this was already implemented long ago and that was half of my intention with the question. Knowledge is power.

Like I said this was just a suggestion as I think it's a small and relatively easy fix. If you simply can't live with that intelligence in the ECU, you can choose not to upgrade if Cliff ever decides to implement it. I can deal with sensor issues on the road side but I prefer not to be forced to (but noticed). Many people have no other alternative than calling for tow.

Quote:

Nevertheless, I still see features like this as "comfort" features only.

When a sensor quits in the middle of nowhere 01.02
in the night on a small country road w no lights,
I`d appreciate the comfort of an Automatic Limp Home Mod.  ;)

You`re so hardcore, luhbo. ::) ;D

The temperature inputs can be done fairly simply with a range check. Air pressure also. The tricky ones are o2 input and throttle
The easiest thing for o2 might be to disable closed loop if the correction hits the 25% limit.

Luhbo wrote on 07/01/09 at 22:34:53:

When do you switch back then? For instance the WBO2 unit sometimes needs nearly a minute before it sends a proper value (other than zero), even if the engine/exhaust is hot. If I start too soon I regularily run into a lean condition because the ecu tries to reach the O2 targets.

But it does send zero while warming up? LC-1 owners can configure it that way too. Then Cliff only need to check for zero volts. Zero volts means temporarily open loop - i.e. as soon as we have something else than zero we can opt to trust it. So you too would benfit immediately, Hubert  :)

Quote:

So still a clever fall back mechanism is needed. It's no solution if you must switch off/reset the unit for that.

That sounds like you would like somekind of  Sensor Error-Limp Home Mod?
I agree.

Guys, that's leading nowhere. Limp on and have fun.
Hubert

_Cliff_ wrote on 07/01/09 at 19:26:22:

The easiest thing for o2 might be to disable closed loop if the correction hits the 25% limit.

That sounds like a good idea, though the "zero volt means N/A" is possibly a good alternative, or even a complement.

Please announce if/when you implement this. I'm especially interested in the closed loop back-off (and by the way I would be very pleased if the software open/closed loop setting is implemented too).

Quote:

So still a clever fall back mechanism is needed. It's no solution if you must switch off/reset the unit for that.

Would be real nice if the Limp Home Mod would be automagic in the new version coming.
Having to physically switch inside the ecu is a real drawback as I see it,
in the middle of the night at a dark road etc...

The Optimiser or ECUController allow you to select either of the o2 inputs, or none.

I think the code should use a default value for a failed sensor, There's nothing like being caught in the fast lane when your engine dies. Perhaps this override state could be signaled by sending the tacho to zero.