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Lambda sensors and popping

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Brian UK View Drop Down
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    Posted: 28 Sep 2014 at 08:54
This affects many models, but has always been an issue with my Norge, popping badly o the overrun. Some have also complained of jerky throttle at low speeds. Now I know there are little black boxes out there which usually cure this, but I can't justify the cost at the moment, so I thought I would experiment.
 
Elsewhere, an American had suggested using just a small diode in the signal line for the o2 sensor, so as they only cost 54 pence I thought I would give it a try. Got a pair of 4 way plugs for £1 so all in, just about affordable.Wink
 
Well it did cure the popping, and it pulled more smoothly at low revs too, but after about 20 minutes the red service light came on. Stopped, turned off then tried again but light still on. Bike running fine of course. Stopped and let bike cool, set off again, light had cleared this time. Again after some time light came on again, no obvious reason, just normal running. So I ignored it. About half an hour later it went off, and then stayed off for the rest of the journey, about another 40 minutes.
Blowed if I know what's going in in that "brain".
 
The diode was a schottky type, bought from Maplin, it has a 0.2 volt drop, so this is clearly just a bit too much.
The idea is that the lambda sensor puts out a voltage between 1.0 volt and zero, the lower the voltage the weaker the mixture in the exhaust, so by dropping the voltage that the ECU sees, the ECU thinks the engine is running a bit weak and richens up the mixture a tad.
 
I shall experiment a bit more for a cheap and cheerful (if not crude) way to alleviate this problem.
Brian.

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Mike H View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike H Quote  Post ReplyReply Direct Link To This Post Posted: 04 Oct 2014 at 14:10
If memory serves messing with the Lambda sensor Voltage on the Norge does trip the warning light, where it doesn't on other models. I remember Dave Shaw had a big prob with it, can't remember how it ended up though. Guess just ignore the  light!
  
That's worth knowing though, just insert a diode. Thumbs Up
 
 
 


Edited by Mike H - 04 Oct 2014 at 14:11
"Chicken nuggets don't dance on a Tuesday."
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Brian UK View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 04 Oct 2014 at 22:28
From what I read on Guzzitech, the Fat Duc device can also bring up the service warning. This is a device which can be adjusted, so you back it off till the light doesn't come on. It affects several models, including some Ducatis which use the same AM5 ECU.
Thought is that though the Fat Duc  is fairly expensive at about £60 is just contains a preset type potentiometer.
My next trial will be to check this out.
 
You realise this will cost me another 50 pence!
 
I am not making any comparison here with other far more sophisticated devices.


Edited by Brian UK - 04 Oct 2014 at 22:30
Brian.

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Mike H View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike H Quote  Post ReplyReply Direct Link To This Post Posted: 05 Oct 2014 at 09:59
"Other devices are available." Big smile
   
Yes I think Dave was experimenting with different resistor values to tweak the degree of change and get itv under the 'threshold'.
  
Interesting that as you are cheating the system, the system is able to detect it is being cheated.
   
Of course it interprets it as a possible faulty O2 sensor.
 
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 05 Oct 2014 at 17:41
I think the light comes on when the ECU gets a reading from the Lambda sensor which is out of normal range. Ie. it thinks the sensor is faulty, though I haven't been able to check what error code is thrown up.
Interestingly if you just disconnect the lambda sensor, the bike runs fine and no service light comes on, though it does generate an error code.
Brian.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Gonzo Quote  Post ReplyReply Direct Link To This Post Posted: 09 Oct 2014 at 19:49
Using Guzzidiag and Tunerpro, both free software, it is possible to turn off the Lambda sensors in the map. This makes the bike more flexible with better low speed running. My Breva 1100 has never popped and banged so I can't promise it will cure that but it has to be worth a try.
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