Loss of power/engine cuts - still there

[njloco]

Like my wife says, just wiggle it !

[Cooter]

...just a little bit....


Haha

[herwawan]

So, update of the day! I took the bike for a long ride this morning to have it warm and do the wiggle tests! The first half was amazing. 30 miles of pure happiness in the canyons, no cuts whatsoever, power everywhere, rock stable idle, working fan, etc. Arrived at the top of the mountain, I wiggle everything I can. Nothing, no wrong, no issues. I decide to head back, and halfway the mess eventually came back, stronger than ever haha

Thankfully I was monitoring the bike with ECMDroid. You can see on the graph below the exact moment it happens. Before the cut point, all is great, captors and working linear and smooth, then a cut happen out of nowhere. For information, I hold the marker on the first cut, which was short (I probably didn't notice it), and right after you can see how it gets way worse (this one, I felt it). The RPM sensor goes crazy at almost 6000 rpm (the bike was at 4000) and you can see the other metrics going crazy:

No go.jpg

Full resolution here

The spark value drops at 0 for the time of the cut, and the veCurr1 which report the fuel map value goes completely crazy (I only displayed here the information from cylinder 1, but the second reports the exact same). The Air Temp sensor (MAT) also lose the reading. You can see that the bike had a really hard time getting over it and I had to stop on the side of the road because it wasn't responding correctly anymore.

At this point, all I wanted was to go home. I drove it back and arrived mid-city, the bike just stopped. And I couldn't fire it back. Here again, good thing is the monitoring was on. See the graph below:

Stop.jpg

Full resolution here

You can tell by how it went before that the bike wasn't very happy before stopping.

This most likely confirms the original input from John and Shaughn, especially since there is definitely improvement since I cleaned the 3 main grounds. But the negative wiggle-test keeps me a bit in the dark. I guess what's left is trying out another ECM as John recommended...

For those who'd like to see the full report, HERE IS the download link.

[Cooter]

With all those sensors being erratic at the same instant, I’d have to lean towards cracked ECM. 4000rpm being the harmonic it doesn’t like.

Idle it with the seat on and bounce around? Or without the seat on it and mash the ecm plugs around with your hand. I’m not making you do silly things hoping for a video or anything.....

[user_deleted]

max: the graphs are "french" to me....no pun intended my friend. but think of your symptoms in these terms: a loss of fuel flow or random ground fault will not completely shut things down. they would emit the sensation more along the lines of simply running out of fuel. what you seem to be describing and guessing the graphs display is a sudden and instant loss of power mimicking turning off the ignition switch. that is pure electrical and a bitch to track down as you're already aware of. i don't advocate randomly throwing parts at it such as replacement ecm, BAS or relays....but like shaughn suggested and i mentioned earlier try and get the bike set up for a "warm motor wiring test" which involves removing the lower cowling, front plastic belt pulley cover, and get yourself a large fan. have someone sit on the bike with it idling approx. 1000rpm....place the fan at the right front of bike so that cool air flows over motor and header assembly.....kick-stand UP....bike in neutral. now work the clutch lever in and out......kickstand up and down.....wiggle the wiring looms at area of front belt pulley.....with long nosed pliers wiggle the wire running from motor towards and past lower cowling right side muffler bracket....and have him move around on the seat.....wiggle harness at steering neck. any change in engine note or immediate shut-down and you've located the fault. also look at recent thread from gregoxb and what he found on his buell.

[GregoXB]

Yes, I found a frayed gray wire in my ECM cable bundles under my seat. My advice is to unwrap the tape from the wires, fan out the wiring and begin methodically inspecting. I recommend doing it outside on a nice sunny day.

[herwawan]

Alright, here's some update folks! First, thanks a lot for the help, leads and advice! The wire-wiggling hasn't lead anywhere yet, keep exploring!

I've borrowed another ECM to see what would happen in the meantime. The bike runs absolutely perfectly (to be fair, it's like every time I ride it it's getting better haha) until it's getting hot and the same cut happened. But this time, nothing weird on the ECM side (in the log). Mitsu from Bartels' is thinking about the cam position sensor. The part has a weird "bubble" that you can feel when you touch it, but not all the time. Depending if it's before or after a good ride, it's different.

As I don't want to throw any more parts at this thing, the goal is to try another used part and see what's happening.

My research on this part matches my exact issues, for example explained in THIS THREAD. The guy is describing the issue much better than I am (probably being native speaker helps!):

My XB9 motor cuts out every time I accelerate to exactly 4,500 rpm like clock work, and it seems to be irrespective of any specific throttle position. When it cuts out there is a complete loss of power and I can't get the engine to get past 4,500 rpm. It's very similar to hitting a rev limiter were the engine bounces off the limit but in this case its only at 4,500. This comes along with some pretty good backfires. It then refuses to run properly again until I pull in the clutch and allow the motor to stall and then I can restart it and carry on (until I hit 4,500 again...) Under no load and parked I can rev the engine past 4,500 without a problem - seems that it needs some load to cause the issue.

And in THIS THREAD they mention how the tach needle can go crazy, which also correspond to my symptom.

So yeah, this is where I stand for now!

[Chicknstripn]

Use a hair dryer and heat up your timing plate. Sounds like your cam position sensor is going crazy when it gets hot.
You know your bike runs fine when it’s cold so heat the timing plate up, on a cold engine, and see if you experience the same running issues.
If the combo hot timing plate/cam position sensor and cold engine make your bike run erratic right off the bat, then you found your issue.
If it doesn’t then you at least ruled that out.
Good luck

[herwawan]

Guys, I have a great news. The problem is fixed, and it was indeed the Cam Position Sensor... The old one was getting crazy once hot.

IMG_1180.jpg


Replaced by a brand new one, and bam, running like a demon! I've spent a good 70 miles driving it around, it's much, much better.

I now have a slight other problem (idle related), but that will be in a different thread and later. Let's just appreciate this victory for now.

VICTORY!