Limp home mode

[raz]

I was hoping for a new thread on limp home mode for ECU's.

OK, here's a starter

 

Quote from V11 WHB: "If a signal from a sensor is interrupted, the ECU acquires its average value. This allows the motorbike to be used (even if it is not in perfect working condition)"

 

It's not 100% clear so we have lots of room to guess, argue and agree.

 

[callison]

OK, here's a starter

 

Quote from V11 WHB: "If a signal from a sensor is interrupted, the ECU acquires its average value. This allows the motorbike to be used (even if it is not in perfect working condition)"

 

It's not 100% clear so we have lots of room to guess, argue and agree.

 

 

Does it specify which sensors? I'd go with any sensor except the TPS although even without the TPS the engine would probably idle. That would be a slow trip...

[Dan M]

OK, here's a starter

 

Quote from V11 WHB: "If a signal from a sensor is interrupted, the ECU acquires its average value. This allows the motorbike to be used (even if it is not in perfect working condition)"

 

It's not 100% clear so we have lots of room to guess, argue and agree.

 

 

Ahh, more theorizing. I'm wondering how it would work on a pre-feedback bike. So few inputs as it is.

[helicopterjim R.I.P.]

OK, here's a starter

 

Quote from V11 WHB: "If a signal from a sensor is interrupted, the ECU acquires its average value. This allows the motorbike to be used (even if it is not in perfect working condition)"

 

It's not 100% clear so we have lots of room to guess, argue and agree.

 

 

AHAH!

 

(.. and thank you..)

[raz]

Does it specify which sensors? I'd go with any sensor except the TPS although even without the TPS the engine would probably idle. That would be a slow trip...

The text I quoted is all there is. And it is probably a poor translation from Italian.

 

Averaging the phase sensor would be a neat trick

[helicopterjim R.I.P.]

Averaging the phase sensor would be a neat trick

 

I see that this is not at all related to the other thread which deals with corrupted signals from the sensors but instead an interrupted signal as in loss of signal. Aside from the phase sensor then a broken wire or damaged sensor would then cause the ECU to go to an average value and produce a limp home mode.

 

Now I wonder if this is an across the board average value or only an average value for the interrupted signal? The interpretation indicates only for the sensor that is interrupted so it may not change much if it is only the ambient air temperature sensor or even the oil temperature sensor. However a loss of TPS signal would probably default to a value that would definitely make the bike limp badly.

 

Next thought. If a loss of signal from say the ambient air temperature provides an average value that doesn't change the ECU function drastically then how would you know that there was a fault if you did not pay too much attention to how your bike is running?

[raz]

I see that this is not at all related to the other thread which deals with corrupted signals from the sensors but instead an interrupted signal as in loss of signal. Aside from the phase sensor then a broken wire or damaged sensor would then cause the ECU to go to an average value and produce a limp home mode.

 

Now I wonder if this is an across the board average value or only an average value for the interrupted signal? The interpretation indicates only for the sensor that is interrupted so it may not change much if it is only the ambient air temperature sensor or even the oil temperature sensor. However a loss of TPS signal would probably default to a value that would definitely make the bike limp badly.

I'm not sure how a native English speaking interprets the quote but I read it as it would have an average of more or less recent data. I'm almost certain that is just incorrect phrasing, surely it's just some preset default values. You could probably get away fine with defaulting to 20 degrees for air temp and say 60 for oil temp. The engine would be startable (though not easily) and then run pretty well, but rich, once at working temp.

 

Next thought. If a loss of signal from say the ambient air temperature provides an average value that doesn't change the ECU function drastically then how would you know that there was a fault if you did not pay too much attention to how your bike is running?

Yeah, especially the air temp sensor and especially in warmer countries than mine. I guess there's more than one bike out there with a faulty temp sensor (or even more likely bad cables and connections). I think later Guzzis (carcs) would throw up an engine warning light of some sort so you know you have reason to investigate. The Sporti has a crude test light but it's under the seat and only temporarily connected for testing. The V11 doesn't have one at all as shipped, right? But it does have the test light connector.

 

Anyone with a cheap ohm meter can test the sensors themselves though. If it's not shorted and not open circuit, it's probably just fine. Best measured at the ECU connector, so you measure it including cables and connectors.