MV Agusta Forum banner

Engine cutting out

6K views 29 replies 10 participants last post by  ruby 
#1 ·
Hi all.

04 Mv Brutale 750.

No this isnt another 'stalling' issue. This is different. I THINK

Ok, quick back story..
Had a severe miss, and alternator issues.. The miss was traced to the fuel system.
The alternator issue is that the ECU isnt sending the 'charge' signal. 'solved' this, by feeding the sense wire battery voltage (same thing the ECU does) directly.

All was good. reved fine in the driveway, alternator is charging like it should. everything was working.

Took it for a ride and all was perfect.. then as i slowed down to stop at the lights, it stalled.. restarted and it was fine, then half way round the corner it stalled again as i changed into 2nd.
Had to push it all the way home.. About 600m in 34 degreeC heat..

From then on it would start, but will not rev past 2200 rpm. It sounds like a kill switch being pressed. starts and idles fine. It revs fine as long as you keep it under 2200.

But as soon as you touch 2200, down she goes.

I have used Adams MIAW software to log whats happening, and at 2200, everything drops to 0. I can post a log if anyone wants a look.

Does anyone have any idea what could be going on?
 
See less See more
#3 ·
One thing I can think of is that infamous SPU, which you have already said had a problem with the charge system......
 
#4 ·
From what I have read/found, the SPU doesn't have anything to do with the alternator, the ECU controls it.

All the wiring diagrams have the sense wire going to the ECU.

I haven't ruled out the SPU, but I have the black back, and haven't had any electrical issues with lights or indicators. Which is why I've been looking at the ecu instead.
 
#5 ·
From what I have read/found, the SPU doesn't have anything to do with the alternator, the ECU controls it.

All the wiring diagrams have the sense wire going to the ECU.

I haven't ruled out the SPU, but I have the black back, and haven't had any electrical issues with lights or indicators. Which is why I've been looking at the ecu instead.

Looks like the battery is still dead level at 12.19v even when your holding 2000rpm, it should be 14.4v, are you sure it is charging?

Can you upload the actual log file ?

Cheers
Adam
 
#6 ·
Hi Adam.

Yeah it still reports as 12.9v. I think this is the same cause/ is the cause, of the alternator not charging via the ecu sense wire.

The alt is certainly charging, can't remember the figures off the top of my head, but I was getting ~13.9v (I think) at 2000rpm.

I have battery voltage going to the sense wire of the regulator, mimicking what the ecu is ment to do, and it has been working fine in the shed up to 7000rpm repeatedly with no issues.

It was only once I took it for a ride that this issue started.

Actually that reminds me, my 40amp charge fuse popped at one point of the bike playing up on the ride, the charge light on the dash come on, it wasn't the first time it stalled, but at some point shortly after.
I have replaced the fuse, and it is showing normal charging behaviour up untill the cutout.

Ill post the full log tonight when I get home.


Sent from my iPhone using Motorcycle.com App
 
#8 ·
Hi Adam.

Here is one of the logs.

I dont think its the same one as i Screen shotted, but still shows what happens.

Had to change it from a .log to get it to upload. Not sure if that effects you.
You can see from the log that it dies every 10secs or so.
The first couple of times it came back up.

Why did your 40Amp fuse blow and why do you always have 32 errors showing in the history ?.
I think you need to get that original charging fault sorted as well.

It all points to the spu, everything goes throught that, the alternator, coils, the lot...

Cheers
Adam
 
#9 ·
Hi Adam. Those drops in revs don't happen in real life. I have other logs where it doesn't show it. I was watching the log when it dropped, the engine stayed at the same revs. Didnt hiccup or anything, I think it was a communication error.

Those 32 errors will not clear no matter what I do. And it's always 32. It has never been another number since I started using your program months ago, bike has been started and run many dozens of times since first using MIAW, and it's still always 32.
Different chips, ecu has been on and off the bike 10+ times, disconnected for weeks at a time, the 32 errors are always there.

I don't know why the fuse blew, I have a new fuse in and it works fine, hasn't blown, but I can't get it past 2200.

The alternator doesn't go through the SPU, at least not on any of the wiring diagrams I have?
The problem with it not charging was the sense wire (which goes to the ecu) isn't being turned on. If I give that wire battery power (which I have done, and this is the way most alternator regs get their 'charge' signal) the alternator charges fine, and when it was revving, the volts come up like they should have, and maxxed out at 14.something.

I'm also not having any other electrical issues, lights, indicators, dash, everything else is working.

I'm leaning towards the ecu rather then the SPU because of the dead alternator sense wire, and the 32 errors that don't exist/won't clear.

I value your input on this Adam. :) just wish I could fix the dam thing.


Sent from my iPhone using Motorcycle.com App
 
#10 ·
Oh, and it always dies at the exact same revs, 2200.
It will idle for 5+ minutes, and will run for 5+ minutes while lightly revving it,
But as soon as you hit 2200 it's gone.

If it was random, i would think its the SPU, but being its so precise, 2200rpm, time after time after time, makes me thing it's not.

Oh, I have tested it with the alt fuse out, to make sure the alt wasn't pumping 16v through or something, and it still does it.


Sent from my iPhone using Motorcycle.com App
 
#14 · (Edited)
Well after stuffing around for bloody months with this bike.

It turns out that I fucked up on the first rule.
CHECK THE FUSES!!

All this started from my alternator not charging..

I checked the big 40A fuse and it was fine, So I pulled the alternator. Had a lot of trouble so I had to remove bits and pieces to get it out.

Alt tested fine. So put it back in. And Jerry rigged the wiring so it would work..

Then on the test ride it started doing this crap.

I didn't link the 2 at the time. Thinking that the ecu was playing up and causing both issues.

After getting a great very helpful guy to plug my ecu and SPU into his bike. Everything tested fine, bike run perfectly. Except the alt wasn't charging with my SPU.

But He found a 5a fuse was blown. So he replaced it and for shits and giggles run the bike again. Hey presto the alternator works!

His bike was still running fine though. So my issue has to be something else on my bike.

He mentioned checking the crank angle sensor. So I did. And immediately realised that it was very loose!! Then I remembered that the wiring was in the way when I was doing the alt, so I took it out. And apparently didn't bolt it back in properly.

So, when it's at idle, the sensor is sitting down as it should, but as I rev, it vibrates and starts to lift away from the engine, and at 2200 the vibrations move it far enough that it loses signal, ECU thinks the engine is stopped, so it cuts fuel and ignition.
Then it drops down into position again. So ill restart it, then rev it again, and it loses signal and stops, and the sensor drops into place again...

So after 8 months of chasing issues, it all comes down to a bloody 10c fuse!!

If it wasn't for that fuse, I wouldn't have pulled the alternator, I wouldn't have taken out the sensor, if I hadn't done that I wouldn't have a stalling issue....

CHECK THE DAMN FUSES!!
 
#17 ·
It was a fun morning, I can now get the tank off, replace an ecu, swap the spu, re-assemble, run/test with my eyes shut having done it 5 times in about an hour.

What I can't do is not pinch the fuel line orings the last time I put it all back together. Turn key on, pump primed, fuel pissing out onto the garage floor :bash:

Repco to the rescue, the imperial assorted oring pack has 3 of the orings used on the quick release lines that come out the bottom of the tank.

Oring replaced, put it all back together, fired it up, no pissing fuel and all tested ready for the ride to work tomorrow just before it started to rain. :smoking:
 
#20 ·
No worries at all, glad I could help! The package was mailed today, you'll get it tomorrow or Wednesday I think.

Thanks for the offer of orings, but I have access to plenty if I pop down to my mates diveshop, unfortunately it's not close by so Repco was the easy quick option on a Sunday.
 
#21 ·
Argh!!

Not quite right yet :(

Took it for a sneaky (it's unregistered) ride this morning towards the servo for some fresh fuel and to pump up the tires.

Got a few hundred mtrs and look down to see the alt light on.
So I pull over, off comes the seat, and sure enough, the 40a fuse is blown.

Not just broken, it's black inside, and one of the terminals fell out when I pulled it out.

Limped it home, put a new fuse in, and all was right with the world...

Reved to 7000rpm, higher then what I did on the ride, and held it there, nothing.. It was fine. Batt was showing 14.2v... Fuse was fine..

So it's only something that happens when I ride it..

This happened last time I rode it, the time the stalling shit started. I thought it was related at the time. But apparently not.

Any ideas on where to check for the short first?

I have revved it in gear, brake lights on, indicators on etc, replicating a ride type condition, and it didn't pop. So my guess is a wire is moving.


Sent from my iPhone using Motorcycle.com App
 
#23 ·
Perhaps the wire that is troublesome is loaded when you are sitting on the bike and moving. Look at wires that are related to seat position and loading...the wire that tuns under the seat to the tail light has a habit of rubbing through at the metal bracket that holds it to the seat.
 
#24 ·
Woot!!
Seems like I fixed it. Couldn't see any obvious shorts, but I cleaned all the connections and tightened them down again.

Run the bike and wiggled every bit of wiring I could, sat on the bike and bounced on the seat and wiggled wiring.
Fuse was fine.

So took it for a ride, 1km to the servo, bouncing on the seat, weaving down the road, hitting pot holes, put a bit of fuel in at the servo and rode the longer 1.5k ride home doing the same thing, even a small wheelie ;) and it was fine!

Still smiling now. That's the first time I've ridden it in more then a year and a half without pushing it back home :)

Gotta be happy with that :D


Sent from my iPhone using Motorcycle.com App
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top