Ducati Monster Motorcycle Forum banner

1 - 12 of 12 Posts

·
Premium Member
Joined
·
1,928 Posts
Discussion Starter #1
So, yesterday we're riding and suddenly Laura's m900 starts popping, losing power, etc.

We stop for a while, ride again for 15 mins or so and it starts doing it again, but worse. I ride it and it feels like one cylinder isn't firing. I gimp it home and it basically has no power and won't go over about 5k rpm. Oil and all the basics are fine....

I get home and think that maybe we just have a fouled plug so I pull them. Horizontal cylinder is black and wet, but not crusty fouled, vertical cylinder light brown and dry. I swap them out with a new pair of NGK DP8EVX-9s. No change. (I did notice that the pair that came out of the bike were resistor plugs, DR8EAs if that makes any difference)

I'm still pretty convinced that one cylinder isn't firing correctly, so I pull one plug wire at a time to isolate which it is. I pull the wire off thye horizontal cylinder first and it runs rough but maintans a pretty even cadence. I then reattach the horizontal cylinder and pull the wire on the vertical cylinder. Now it won't run... Now I assume that it's the horizontal cylinder that's my problem.

I know that the plugs are new, so I decide to test the coils and plug wires by swapping them and assuming that if it's a bad coil or wire, the problem will move to the vertical cylinder. as I'm pulling the wire from the horizontal cylinder, the plug cap comes right off the wire, so I'm thinking that I've found the problem.

I see in the parts manual that the coil and wire assembly and the plug cap are separate parts and although I find it to be an extremely half-assed way to build ignition components, I go ahead and re-assemble the cap to the wire and move it to the vertical cylinder and move the other assembly to the horizontal cylinder. The bike still runs like crap. I pull the plug wires one at a time and the problem is still with the horizontal cylinder.

I also visually confirmed that I'm not getting any spark for the horizontal cylinder.

Now I'm a little stumped. As far as I can tell, the wires from the coils go directly to the ECU. I ohmed out the pick-up coil and it read 698 ohms which is in spec according to LT Snyder's book. I also continuity tested the gray and yellow wire that goes from the coil to the connector on the ECU and the brown and white wire back to ground, both checked out OK.

I'm feeling that I'm to the point where I'm going to need someone with diagnostic equipment to check the computer, but I don't have anyone local that I trust, so I'm looking at a trip to Nevada or Texas to get it looked at. Before I do that, does anyone have any more suggestions that I can check myself before making an appoitment with AMS?

Thanks,
--Fillmore
 

·
Premium Member
Joined
·
613 Posts
I'd be inclined to check fuel, as in fuel filter?? I think your starving.
 

·
Registered
Joined
·
100 Posts
my S4 front coil has just expired after 2500 miles. I don't know if it was a dud to begin with or if the Scottish winter did for it. I also swapped the coils over (they mount directly on the plug on the S4) and the fault moved with it, Japanese coil so I can't blame Italian electrics. No run for me this weekend.
I can't help thinking that directly behind the front tyre, which throws up stones, grit, salt and a lot of water, is a really stupid place to put a high voltage ignition coil which doesn't even have a rubber sleeve to protect the connections. Anybody up north have this trouble in the winter? and when I put in the new (warranty) coil will it croak again one day, in a downpour 100 miles from nowhere?
I had an SV650 which went onto one cylinder when the plug cap started shorting out in the rain, I had to remove the bolts and slide the radiator out of the way to get the plug cap out and dry it, before putting it back together with some rtv silicon on it. That's two times twice on bikes with the cylinder pointing at the front wheel. Think I'll get another Africa twin, at least I can ride it in the winter.
 
M

·
Guest
Joined
·
0 Posts
Can you test to see if you've got juice going to the coil? Obviously if there's spark getting to the coil but not to the cylinder then your coil is the problem. I'm not sure if I read your post correctly, but did you switch coils from one cylinder to the other and still get the same result with the same cylinder not running? If that's the case then it eliminates the coil as the culprit. and leaves you with whatever is upstream of the coil, which sounds like the e.c.u.
 
D

·
Guest
Joined
·
0 Posts
I had the same exact problem with my 2000 m750. And I located the problem. On mine there is an inline fuse that runs along the left side of my battery. The wire runs from the pick up for the the horizontal cylinder ignition coil. What I found was a cold solder joint from the wires being tinned with solder at the contacts on both sides of the fuse. I am currently researching a new way to crimp better contacts for the fuse. But for the time being I cut out the inline fuse and spliced the wires together. The problem vanished. As soon as I get a better inline fuse figured out I will let you all know. I am not sure if this will be the right fix for your bike but that is what I found for mine and the problems sound exactly the same. If you prop up the tank (without a full tank.....ooops) and locate the inline fuse I am talking about and mess with it and wiggle it around while it is running I would like to hope you will find the problem. I hope this helps.
 

·
Premium Member
Joined
·
1,928 Posts
Discussion Starter #9
News... I gave up and took it to Ben Fox at Fox Performance up in Co. Springs.
 

·
Registered
Joined
·
86 Posts
On the plus side, once he gets it running right, he's gonna dyno tune and re-map the chip so it should be better than even when it comes back.

--Fillmore
Sorry to go off-topic.....

There's someone in Colorado that remaps the ECU? Would that remapping address the altitude issues so a PC isn't needed? What do they charge?
 

·
Premium Member
Joined
·
1,928 Posts
Discussion Starter #11
Yep...
http://www.foxperformanceengines.com/

He's in the `Springs right now, but moving up to Denver in conjunction with a new shop opening up there.

Give him a ring for pricing.

--Fillmore
 
1 - 12 of 12 Posts
Top