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Breva 1100 - Low Idle Speed

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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: 08 Jul 2018 at 16:26
Measure twice, cut once. Worth going back and rechecking.
However that won't have changed so if the idle etc has then its probably not that.
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Tris View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tris Quote  Post ReplyReply Direct Link To This Post Posted: 08 Jul 2018 at 20:22
Totally agree re measure twice! I've made a little fixture to help me get everything square

The existing sensor appears a bit swollen and definitively isn't square to the flange, so for the price they are I've ordered a replacement 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Petros GR Quote  Post ReplyReply Direct Link To This Post Posted: 08 Jul 2018 at 23:22
I would use guzzidiag to look the oxygen (lambda) sensor reading. After its heated up it should fluctuate at any value between 100 and 900 mV. Lambda reading afects how the engine runs when under 3000 rpm...

If the sensor reads normal, I would try to raise the idle, using the "CO trim" actor. The defalult trim value is 0 (zero). I would start by seting it to, lets say 50, and see how it goes, increasing or decreasing it according to the result of the previous value. This value represends milisec added (or substructed if negative) to the duration of the fuel injection. As CO trim value is added (or substructed) for all engine operation, going too high (or low) can result in running rich (or lean), so even if i could get the iddle at 1200, I would later check the plugs to see if the bike runs rich
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tris Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jul 2018 at 07:26
I've measured and remeasured everything about 20 times now using 3 different techniques now and keep getting the same answer - original air gap was set at 0.9mm

The good news is that one of the shims is 0.3mm thick so if I pull that I get the right answer - wahoo Smile

Once the new sensor arrives tomorrow I'll start to stick it back together and see where we are

Petros
I'll bear that in mind, but I thought unless the Lambda sensor is disabled via Guzzidiag, then the Autolearn would dial it back out over time



Edited by Tris - 11 Jul 2018 at 07:30
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jul 2018 at 13:54
Bear in mind the new sensor may not be exactly the same dimensions so you will have to check again.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tris Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jul 2018 at 14:38
Thanks for the reminder Brian but if I'm lucky it will simply be "plug and play"
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 12 Jul 2018 at 07:08
That is why the shims are there.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote David_M Quote  Post ReplyReply Direct Link To This Post Posted: 12 Jul 2018 at 13:54
Do you mean 'Plug and Pray'?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike H Quote  Post ReplyReply Direct Link To This Post Posted: 12 Jul 2018 at 19:56
I wouldn't put the new one in assuming the gap will be correct.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tris Quote  Post ReplyReply Direct Link To This Post Posted: 25 Jul 2018 at 07:15
Well he's back together with no bits left over ... which is always nice Wink

The good news (bar final tuning) is that it looks like its sorted as he fired straight up and settled down to a proper idle

If I blip the throttle now there are no pops and bangs and no tendency to stall/idle low

I can't be certain as I disconnected and re-made pretty much every connection of the engine management side, checked every component against the specs and replaced all 4 plugs but the only issues I found were with the Cam sensor
  1. Possibly slightly swollen - difficult to be sure
  2. Air gap definitely set at 0.9mm and not 0.6 to 0.7mm
  3. Its subjective, but the old sensor felt less "magnetic" than the original when I managed to stick a spanner accidentally to one causing me to check the other.
My hypothesis for what its worth is that a poor signal from the cam sensor due to weak magnet/excessive air gap gave the ECU a false impression of the actual RPM which is why it stubbornly stuck to a low actual idle speed as it was thinking it was higher

I'll report back once I have been for a ride and finessed the tuning

Thanks for everyones' input
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 25 Jul 2018 at 16:35
Yes, that's quite possible, those sensors do fail.
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