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Discussion Starter #1
Hi there guys

I am new here so apologies if I haven't posted this correctly.
I have a 2013 MV Agusta Brutale 800.

I have just replaced the sprag (starter) clutch which was deteriorating slowly over about 6 months.
After putting her all back together the bike is throwing up a Phase Sensor error and idling high and horribly, if I blip the throttle the revs go up very slowly and come down slowly.
I tested the RPM/phase sensor with my multimeter and I am getting the correct resistance.
Parts I touched areI removed the fuel tank, air box, throttle body to get to the starter assembly. What did I cock-up?
 

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Welcome to the family @Bobby86 !!! How many miles on your bike now? That could influence causes.

Did you have the ECU map upgraded for the new sprag? That is part of the "cure" for sprag failures.
I'm not sure what you could have done. Phase sensor error can be caused by a weak battery...does it go away once engine is running? If the fault stays on then the ECU may be in a limp mode??? I really don't know, just guessing,
 

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Teh ECU update Ed mentions is to alter the starting protocol to help the SPRAG stay viable.

The old mechanic's adage says that whatever new problem you are having now is directly related to the maintenance you just performed.

Check your work thoroughly. I'd suggest it is in an electrical connection or wire routing.
 
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I had a phase sensor error come up when I was getting a bunch of work done over the winter(clutch basket replacement, new map and a full bazzaz system) the battery had died over the winter because the fools storing the bike didn't keep it on a tender. So a lithium battery was put in, sure enough the battery didn't quite match up and when the repalced it with a stock crap oem battery the error went away. So I'd check the battery first.
 

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Discussion Starter #6
Welcome to the family @Bobby86 !!! How many miles on your bike now? That could influence causes.

Did you have the ECU map upgraded for the new sprag? That is part of the "cure" for sprag failures.
I'm not sure what you could have done. Phase sensor error can be caused by a weak battery...does it go away once engine is running? If the fault stays on then the ECU may be in a limp mode??? I really don't know, just guessing,
Wasn't sure if I would get any replies to this post. Seems like a great family!

It's on 21000km, 13000miles
I didn't do an ECU upgrade. Didn't see anything online saying it was necessary.
The battery is brand new. The bike is starting and the error does not go away.
I have just disconnected what I thought was the Phase sensor and then the error "RPM Sensor STOP ENG" popped up.

Thanks for the advice!
 

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Discussion Starter #7
Teh ECU update Ed mentions is to alter the starting protocol to help the SPRAG stay viable.

The old mechanic's adage says that whatever new problem you are having now is directly related to the maintenance you just performed.

Check your work thoroughly. I'd suggest it is in an electrical connection or wire routing.
I will look at an ECU upgrade soon then! I checked the connectors on what I thought was the phase sensor. When this was disconnected it showed error "RPM Sensor STOP ENG".

Is the phase sensor different to the RPM sensor? Confuzzled now!
 

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Yes.
 

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Discussion Starter #9
I had a phase sensor error come up when I was getting a bunch of work done over the winter(clutch basket replacement, new map and a full bazzaz system) the battery had died over the winter because the fools storing the bike didn't keep it on a tender. So a lithium battery was put in, sure enough the battery didn't quite match up and when the repalced it with a stock crap oem battery the error went away. So I'd check the battery first.
Thanks for the advice!
It's a new battery. The bike is starting and error does not go away. Maybe I should get my car battery out :LOL:
Curious what was your new map for?
 

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The new map has changes for the starting protocols that improve sprag life (among other things).
Phase sensor is referring sensor that tells ECU which cylinder is on compression stroke so it knows which coil and injector to fire and when.

I am not certain, but I think the 3 cylinders use a vacuum pulse on cylinder one intake for that signal. Look for a vacuum hose leak perhaps? and the sensor that intercepts that hose.
Otherwise it is a hall affect sensor in the head or valve cover that a reluctor on one camshaft triggers as it goes past in rotation. Sometimes bits of metallic debris or other gunk will stick on that sensor disrupting the signal. Take it out and clean it.
Workshop manual should point you to it and what type it is.
 

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Thanks for the advice!
It's a new battery. The bike is starting and error does not go away. Maybe I should get my car battery out :LOL:
Curious what was your new map for?
The map was just the lastest fueling update from MV, my bike is a 2013 so it hadn't been in to an official dealer for stuff like that for a bit. I can't remember if they said it needed it for the clutch basket but the guy doing the bazzaz and dyno tune said get everything up to the latest. The battery was a new lithium ion but I guess just slightly different enough in spec to cause the issue. So I'm just waiting for that oem one to fail me and I'll put in a proper aftermarket one again :p
 

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In MV parlance, you are correct....when I read your original post my brain converted RPM to SPEED...which are different animals.

MV doesn't really discuss what PHASE means, but I think we have mostly established that PHASE ERROR occurs when the engine RPM does not match the ECU predicted speed...especially during the START SEQUENCE. This is one of the reasons MV changed the START SEQUENCE programming in the ECU for sprag issues. The ECU program is part of the process of fixing the sprag failures.

Interesting
483685
that the manual says this about PHASE ERROR:
 

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That diagnostic procedure (See above) confirms the ECU is using a pressure signal (vacuum) from one cylinder to determine which cylinder is on what stroke. Look at all those rubber hoses (especially to left (#1) cylinder.
 
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