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Discussion Starter #1
So.I washed my 2002 ss and this was the first time I've ever used water.Idles fine but wouldn't rev higher than say 2000rpms.Had to do 60 miles in limp home mode.Dried out plugs and leads no difference.Parked it up for a couple of days and it runs fine no problems at all.A day later I get a light drizzle on my way into work and the bike starts losing power and backfiring.Rained all day and had to get recovered as the poor did would not rev higher than 1000rpms without backfiring and cutting out.Ive changed fuel,plugs and and the fuel filter.Been two weeks since and had no improvement.The backfire seems to be through one cylinder only with the air filter out i can feel and hear it but there is bo visable smoke vapour or spark.Any advice would be much appreciated.
Cheers
 

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Not an expert, but the fact that this occurs in the presence of water would lead me to believe that you have an electrical connection in the ignition or ECU systems that is getting wet and becoming problematic. Check if you have a connector that is obviously exposed to the elements. Clean and re-seat the connectors. You can wrap exposed connectors with silicone sealing tape if you want, but no need to go crazy. Avoid putting dielectric grease on the connectors as this frequently causes more problems as dielectrics are insulators and can impact pin conduction.
 

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My bet, with the bike being of that age is the spark plug wires being grounded intermittently. Clearly it's an ignition problem and the wires are easy to change relatively. Next would be any rubber seals that seal ignition components. Work back through the system with the dumb stuff before you start throwing money at this thing. The ignition appears to work when it's dry, so it has to be a rubber seal or wire that is allowing moisture to pass.
 

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If it is working fine when dry try specifically adding water to components and testing .

Use a small hand squirter and I would start with one plug wire at a time. get it good and wet (no high pressure) and see if the problem comes back. If it is still fine with one then move to the next and work your way through most of the electrical components. If it never comes back step up to a garden hose and do NOT blast it but again start with one and work your way around wetting the plug wires. Never use a pressure washer on a motorcycle.

Backfiring in the airbox can be a lean condition so pay attention to if it is one cylinder or not.

If it is NOT water related then you may have a bad ecu, crank angle sensor, TPS unit and the water is just pushing it over the edge.
 

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Discussion Starter #5
Hi guys thanks for the responses.Unfortunatley the problem os now permanent.It appeared to be water causing the probelm as you say but now its been sititng for 3 weeks and is now dry.Always backfires around 3000rpms and is unrideable.I will check out the the HT leads.I have a factory manual but it gives no specs for any of the ignition components or sensors?
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You changed fuel filter is there a chance there is water in the fuel?

Did you check for a split fuel line?
I would check fuel pressure.
what do the plugs look like ?
Is the airbox lid all stock or modified?
exhaust?
last tune?

It is possible something has changed fueling requirements so look for bad things first (water,split lines ,bad plugs) . After that you may need to use software to check for a bad sensor or adjustment (tune). You also need to start with a bike that is running right so make sure nothing around this time has changed like exhaust or airbox without being adjusted to suit.
 

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Discussion Starter #8
When I changed the fuel filter I completely emptied the tank as when I opened it I found the drainage and main breather to be blocked.I managed to free the drainage but not the main breather.I changed the plugs at the same time.The plugs I removed had heavy carbon deposits.So initially I would have thought this was too rich.Air box and exhaust are all standard no modifications at all.Id love to get it plugged into a diagnosis tester such as the Mathesis but I don't have access to one.Im gonna test the leads and coils for resistance although I don't have any figures to compare them against.Ill also check the throttle position sensor and see see what the throttle body sync looks like.Its weird if you roll on the throttle fast it revs up fine.But if you gradually bring it on say to hold a speed of 20-30mph specifically at 3000 to me the tachometer instantly drops to 0 and bounces back and fourth whilst backfiring and losing power until it stalls.
 

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If the tank breather is still blocked it likely can't pump fuel as it would draw a partial vacuum in the tank. Have you tried starting it with the fuel cap open?
 

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if the tacho drops to zero while the engine is still turning it's indicative of a rotation sensor failure or general ecu power failure.
 

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Discussion Starter #11
I have tried running with the tank open and unfortunately no difference.I ran it up and down my street to see if that would make a difference.
I'll check the cps as well then.I take it other than using a.c. on a volunteer for signal output and voltage suly in an ocilliscope is my only other option to test this?
Cheers
 

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I have tried running with the tank open and unfortunately no difference.I ran it up and down my street to see if that would make a difference.
I'll check the cps as well then.I take it other than using a.c. on a volunteer for signal output and voltage suly in an ocilliscope is my only other option to test this?
Cheers
CPS you can test with a multimeter aka voltmeter or even a volunteer>:)
This is on a.c. and from memory should be around 2 Va.c.

It could also be the throttle position sensor or a connection to it.
It is a potentiometer and the ECU reads the voltage of the "wiper" to determine the throttle position.
Closed it should be about 475 mV and fully open around 4900 mV.
If there is a corrosion related resistance in the positive or negative to the TPS, then the TP reading will be incorrect.

The tacho dropping quickly to zero does indicate an issue with the CPS or connections.

Another thing to watch out for is when lowering the tank. It is possible to kink the hoses, so watch carefully and guide the hoses so they do not kink when lowering the tank.
This can cause fuel starvation.

Also check the battery to frame earth point for corrosion or use a multimeter on the lowest resistance scale to measure between battery negative to the engine. Something like the spark plug hole with the plug out as this is bare metal. It should be so close to zero.
When measuring resistance, I first touch the multimeter probes together to see what "zero" is actually reading.
If you have some resistance, then the ECU may get weird readings when the engine is running faster and more current is flowing and by Ohms law, voltages will be out of whack.

You don't need a Mathesis tester.
The IAW Diagram software and Lonelec cable/adapter will let you test/see what is going on.

As you used mph, I guess you are in the US, so no point in offering my cables or assistance.

The only other sensors that feed into the ECU are air temp (behind the headlight), engine temp (on the horizontal head) and air pressure (on the PCB in the ECU)
None of these three would cause the symptoms you have.

I suggest you edit your "User CP" and put in where you live and that will always show on the left of the screen under your Avatar and user name.
You never know, someone from here might live just around the corner and be able to help.
 

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Start with the simple stuff. Change spark plugs, check coils and wires for cracks, same with any wiring or connectors for the ignition.
 

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Bad plug caps will do this too.
 

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i'd check the end gap on the rotation sensor too. maybe water in the connector pushed it over the edge.
 

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Discussion Starter #17
Hi guys so still finding the time to get on to working at my problem.Does anyone have any ideas where I can get stats to test my fuel injection system components against?I have a factory manual for my bike but for all fuel injection settings it simply tells me to plug in Mathesis tester.
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the older 888 or 916 or maybe 97 st2 manuals have specs, but you're far better off seeing what the ecu is seeing via a diagnostic tool. it doesn't matter what you think is happening, it matters what the ecu thinks is happening as it is in charge.

get the lonelec cable.
 

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Discussion Starter #19
Lonelec cable.I assume this is go be used in conjunction with something like jpdiag?I've heard mentions of this?
 
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